Testosterone Gel: The Definitive Guide

What is testosterone gel?

Testosterone gel is a prescription form of testosterone that you rub onto the skin once a day, usually in the morning. It is plain testosterone dissolved in a clear, alcohol-based gel. The alcohol dries within minutes, the outer skin holds the hormone like a reservoir, and testosterone passes into the blood over the next 24 hours. Only a small share of what is applied is absorbed (about 10% for AndroGel 1%); much of the rest stays on the skin for hours, where it can rub off. [1], [2], [3]

The route is called transdermal (absorbed through the skin). Unlike injectable testosterone, gel has no ester, the chemical tail that slows release from an oil depot; the skin itself does the slowing. Gel left on the skin can also pass to anyone who touches it, which is why every US gel label carries a boxed warning. [4], [2]

Gels are labeled for men with hypogonadism (low testosterone from a medical cause): primary hypogonadism, where the testicles fail, or hypogonadotropic hypogonadism, where the brain and pituitary do not send enough signal. US labels still say safety and benefit in "age-related" low testosterone, and under 18, have not been established. AndroGel 1% was the first US testosterone gel, approved on February 28, 2000. [4], [5]

In 2024, Medicare Part D recorded 556,670 fills (including refills) for 132,638 people under its generic "Testosterone" entry, which combines every form and strength of generic plain testosterone, gels included. [6]

[4], [1], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18]

Where each product is sold was checked in September 2026. Canada also sells Taro's 1% gel, and Australia a 1% Testogel (legal status). Testosterone gel is a controlled substance: Schedule III in the United States. Compounded testosterone creams and gels made by pharmacies are different products with no approved label; see compounded testosterone cream. [19]

Typical Testosterone Gel Protocols

Every label starts with one application a day, usually in the morning: 40.5 mg of a 1.62% gel, 50 mg of a 1% gel, 60 mg of Tostran 2% gel or the 2% solution, or 23 mg of Testavan 2% gel. The amount is then adjusted in steps using blood tests, within ranges such as 20.25–81 mg for 1.62% gel and 50–100 mg for 1% gel, where the guideline ranges also sit. [4], [1], [7], [9], [13], [14], [23], [26]

Titration Adjusting the dose in steps

The US AndroGel 1.62% and Testim labels adjust by a pre-dose level, drawn in the morning before that day's gel. The 2% products and most guidelines use blood drawn 2 to 8 hours after application instead. Hematocrit can also force a change. [4], [7], [9], [13], [23], [26] See why the draw time matters.

Breaks and cycles

Not applicable. Testosterone replacement is continuous treatment, and no label or guideline describes planned breaks. Levels fall back within days of the last application (what happens when you stop).

Read the units. Gel is measured in pump presses, packets or tubes, not syringe units, and a press means nothing without the product: 20.25 mg from a 1.62% pump, 12.5 mg from a 1% pump, 10 mg from Tostran, 23 mg from Testavan and 30 mg from the 2% solution. So 40.5 mg of AndroGel 1.62% is 2 presses (2.5 g of gel), while 2 presses of a 1% pump is only 25 mg. An 88 g AndroGel pump holds 60 presses, a month at 2 presses a day, after 3 priming presses are discarded. [4], [1], [13], [14], [9]

These are labeled and guideline doses; prescribers adjust them using blood tests and symptoms. The amounts above are for adult men. For women, see testosterone therapy for women, which uses different products and far smaller doses.

Cautions for every schedule above. The US labels rule out testosterone gel with breast cancer or known or suspected prostate cancer, and in pregnant women, because it can harm a female fetus. Gel must be kept off children and partners (how). It can shut down sperm production (fertility), and hematocrit, blood pressure and PSA (prostate-specific antigen, a prostate blood test) need checking (monitoring). [4]

Where schedules differ: blood-test timing, brands and twice-daily use ↓

What is testosterone gel commonly used for?

Its approved use is replacing testosterone in men whose bodies cannot make enough because of a medical condition: testicular failure (for example from undescended testicles, removal, chemotherapy or Klinefelter syndrome) or a missing signal from the brain or pituitary (from a hormone deficiency, a tumor, injury or radiation). [4]

Some guidelines prefer gel to start. The European Association of Urology (EAU) suggests gel rather than a long-acting injection when starting treatment in men at high risk (unlike a depot, gel clears within days of stopping), and the European Academy of Andrology, for men with functional low testosterone (from causes such as obesity or illness rather than damage to the testicles or pituitary), puts exercise and weight loss first and suggests a transdermal preparation if testosterone is started. A 2020 American College of Physicians guideline, now listed as inactive, instead suggested injections for age-related low testosterone because they cost less. [28], [4], [29], [30]

What does testosterone gel improve?

• Sexual function and mood. In the AndroGel 1% approval trial of 227 men, sexual function and mood improved by day 30. In TRAVERSE, men with low sex drive had about 0.5 more sexual acts a day than on placebo, with more desire, but erections did not improve. In the Testosterone Trials of men 65 and older, a year of 1% gel improved sexual function and mood a little. It did not improve energy (vitality), and walking improved only slightly when all the men were counted, not in the men chosen for walking problems. [31], [32], [33]
• Muscle and fat. In the same AndroGel trial, lean mass rose 2.74 kg on 100 mg and 1.28 kg on 50 mg after 90 days, while fat fell by about 1 kg. In the Testim approval trial, lean mass rose 1.7 kg over 90 days on 100 mg a day, significantly more than on a patch or placebo. [31], [34]
• Bone and red blood cells. In men followed for up to 42 months on AndroGel, spine bone density rose. In TRAVERSE, anemia was corrected in 45.0% of men on testosterone vs 33.9% on placebo after a year. [35], [36]

These are average effects in trials; see the evidence and the results timeline guide.

How long does testosterone gel take to work?

Blood levels move fast; symptoms move slowly. With AndroGel 1% 100 mg, testosterone rose within 30 minutes of the first application and was in the normal range in 8 of 9 men by 4 hours, and levels settle into a steady daily pattern after 2 to 3 days. In the AndroGel 1% trial, sexual function and mood had improved as much as they would by day 30, while the Canadian Urological Association tells men to expect changes in sex drive, energy and sexual function after 3 months or longer. [1], [37], [31], [25]

Where do testosterone gel protocols differ?

Each label is clear about its starting dose. The disagreements are about when to draw blood, what level to aim for and whether one brand can replace another.

When should blood be drawn on testosterone gel?

It depends on the product and the guideline. Gel levels rise in the hours after each application, so a sample 2 hours after the gel and one just before the next dose describe the same dose at different moments. [4], [23]

[4], [9], [13], [14], [23], [24], [38], [26], [39]

The pattern: the US 1.62% gel and Testim labels judge the dose by the lowest point of the day, while the 2% products and most guidelines judge it closer to the peak. The numbers are not comparable, so writing down the hour of the last application next to each result matters. [7], [13], [4]

Draw blood from an arm without gel. Gel where the needle goes in can make a result falsely high. In one hospital's records of 578 gel users, 48 had a result above 1,000 ng/dL, and gel on the draw site was the likely cause in 7. In another study, blood from the gel arm read 33.2 nmol/L against 14.2 nmol/L from the other arm. UK guidelines say to avoid the application site. [40], [41], [26], [39]

Is one gel brand the same as another?

No. The US labels say the application site and dose "are not substitutable with other topical testosterone products". Formulations differ, and so does how much gets through the skin. [4]

• Testim versus AndroGel 1%. In 29 men given one 50 mg dose of each, Testim produced 30% higher total testosterone exposure and 47% higher free testosterone; the two were not bioequivalent. [42], [43]
• Pharmacy substitution. FDA rates AndroGel 1% and its generics as one group (AB1) and Testim, its generic and the Vogelxo packet as another (AB2); a pharmacy can swap only within a group. [5]
• Switching after a poor response. In 75 men who switched brands because their levels stayed low, moving from AndroGel to Testim raised average testosterone from 311 to 484 ng/dL; moving the other way did not. The AUA calls switching to another topical product a reasonable option. [44], [38]

A brand change is a dose change, so it usually means a new blood test.

Is one application a day enough, or should it be split?

Every label and guideline gives one daily application, mostly in the morning. No trial has tested twice-daily or split applications of an approved gel, so no source gives a split schedule; some people report a dip before the next dose (community). On gel, the average daily curve is fairly flat, but each man's peak arrives at a different time of day, one reason single results vary. [4], [23], [45]

What happens when you stop testosterone gel?

The gel leaves quickly; your own hormone production takes much longer to return.

• The gel itself. Testosterone returns to about where it started within 48–72 hours of the last AndroGel 1.62% dose, and by the fifth day after AndroGel 1%; UK Testogel gives 72–96 hours. [4], [1], [10]
• Your own testosterone. Gel turns down the pituitary's two signals to the testicles, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), in proportion to the testosterone it adds. Recovery depends on the original cause and how long treatment lasted; in men with a lasting cause, low testosterone returns. No study has tracked recovery after long-term gel specifically. [2]
• Sperm. In contraceptive trials of healthy men given testosterone-based regimens, sperm counts returned to 20 million per mL in 67% within 6 months, 90% within 12 months and 100% within 24 months. [46]

See stopping TRT for the full picture.

How does testosterone gel compare with other forms?

Gel gives a fairly flat average daily level and clears within days, and the Endocrine Society says high hematocrit is less common on gel than on injections (a pooled analysis of trials could not show a clear gap). But it is a daily task, its absorption varies from man to man, and it can transfer to other people. [45], [23], [47], [4]

How much gel gets into the body?

About 10% of the testosterone in AndroGel 1% is absorbed; one early study measured 9–14%, the UK Tostran information gives about 12% and the UK Testogel 16.2 mg/g information 1% to 8.5%. Absorption varies between men, which is why labels adjust the dose by blood tests. [1], [2], [13], [10]

With the 2% gel, 79.1%, 79.5% and 73.8% of men reached the normal range from the lightest to the heaviest third, and heavier men were on higher doses; the AndroGel 1% trial found no difference by body mass index. [48], [1]

Doserly

What changes blood testosterone from gel

Change in measured blood testosterone (exposure or average level), against each study's own comparison. Bars to the left of the line mean lower; to the right, higher.

Where it goes on

Abdomen instead of upper arms and shoulders: −30 to −40%

AndroGel 1.62%, 81 mg, 36 men · total exposure (AUC) · Miller 2011

Testavan on the abdomen: −33%

vs upper arm and shoulder · average 372 vs 557 ng/dL · UK information

Testavan on the thigh: −29%

vs upper arm and shoulder · average 395 vs 557 ng/dL

Showering after applying

Shower 15 minutes after: −68%

50 mg gel, 10 transgender men · average 320 vs 994 ng/dL · de Ronde 2011

Shower 30 minutes after: −60%

same small study · average 401 vs 994 ng/dL

Shower 2 hours after: −13%

AndroGel 1.62%, 81 mg, 24 men · average level (Cavg)

Shower 6 hours after: −12%

same study

Shower 10 hours after: no change

same study

Other products on the skin

Antiperspirant 2 minutes before: up to −33%

2% solution, 30 mg in the armpit, healthy women · total exposure (AUC)

Sunscreen 1 hour after: +8%

AndroGel 1.62%, 40.5 mg, 18 men · average level (Cavg)

Moisturizer 1 hour after: +14%

same study

Wait your product's full washing time and use only its label sites. Sunscreen or moisturizer an hour later raised levels only slightly.

Where can testosterone gel be applied?

On clean, dry, intact skin, and only where your product's label says, because the site changes both absorption and transfer. [4], [37]

[4], [1], [7], [9], [10], [13], [14]

• Abdomen and legs. AndroGel 1.62% on the abdomen alone gave about 30–40% lower exposure than on the upper arms and shoulders. With Testim, levels were highest from the shoulders and arms and lowest from the legs, and Testavan on the abdomen or thigh averaged 372 and 395 ng/dL against 557 ng/dL on the arm and shoulder. [37], [49], [14]
• Scrotum. No US or UK gel is labeled for genital skin. Scrotal skin absorbs far more: 25 mg of cream there kept testosterone in the normal range for 16 hours, and the only approved scrotal product among those reviewed is AndroForte 5, a cream sold in Australia (compounded testosterone cream). [50], [51], [52]

How long should you wait before showering, swimming or using lotion?

Follow your product's wait: at least 2 hours for AndroGel 1.62%, Testim, Vogelxo, the 2% solution, Tostran and UK Testavan (1–2 hours for Australian Testavan); 5 hours for AndroGel 1% and its generics; 1 hour for UK Testogel. The UK Society for Endocrinology advises 6 hours. [4], [1], [50], [7], [8], [9], [10], [13], [14], [26]

• Very early washing matters. In one small study in transgender men, showering 15 or 30 minutes after a 50 mg gel lowered average testosterone from 994 to 320 and 401 ng/dL. [53]
• Washing after the wait matters little. Showering 2 or 6 hours after AndroGel 1.62% lowered average exposure by 13% and 12%; at 10 hours it made no difference. [4], [54]
• Moisturizer and sunscreen. Applied an hour after AndroGel 1.62%, moisturizer raised average exposure by 14% and sunscreen by 8%; the UK Testogel information says neither reduces efficacy. [27], [10]
• Antiperspirant. With the underarm solution, antiperspirant goes on at least 2 minutes before; in a study it lowered exposure by up to 33%. [9]
• Exercise and sweat. No study has measured the effect of exercise or sweating after application.

Alcohol gels are flammable until dry, so avoid fire, flames and smoking until the gel has dried. [4]

AndroGel 1% and 1.62%

AndroGel is the original US testosterone gel: AndroGel 1% was approved on February 28, 2000 and AndroGel 1.62% on April 29, 2011. The two strengths are dosed differently. [5], [4]

• AndroGel 1.62%: 20.25 mg per press, starting at 40.5 mg each morning on the shoulders and upper arms only. In its approval trial of 274 men, 81.6% (146 of 179) had average levels in the normal range at day 112, and 11.2% had a peak above 1,500 ng/dL. It is the gel used in TRAVERSE. [4], [55]
• AndroGel 1%: 12.5 mg per press, starting at 50 mg, adjustable to 75 or 100 mg; it may also go on the abdomen and needs a 5-hour wait before showering. In its approval trial, 87% of 129 titrated men had average levels in range at day 180. [1]

Generic 1% and 1.62% gels are rated equivalent to the matching AndroGel. Canada sells AndroGel only as the 1% gel; France sells a 16.2 mg/g AndroGel. [5], [16], [17]

Testim and Vogelxo

Testim is a 1% gel in single-use 5 g tubes (50 mg), approved in the United States on October 31, 2002, and also sold in Canada. It goes on the shoulders and upper arms, never the abdomen, and may have an alcoholic or musk odor. In its label studies, 74% of 192 titrated men were in range at day 90, and it delivered about 30% more testosterone than AndroGel for the same 50 mg. Vogelxo (approved June 4, 2014) is a 1% gel in tubes, packets or a pump; its packet is rated equivalent to Testim. [5], [7], [21], [42], [8]

The 2% underarm solution

A liquid rather than a gel: 30 mg per press, applied with an applicator cup to each armpit (60 mg a day to start, 30–120 mg), and judged by blood drawn 2–8 hours later. In its label trial, 84.1% of men were in range at day 120. The brand, Axiron (approved November 23, 2010), was withdrawn on July 23, 2018, not for safety reasons; generics remain. [9], [5], [56]

Testogel, Irisel, Tostran and Testavan (UK, Europe and Australia)

• Testogel 16.2 mg/g (UK): 40.5 mg a day from a pump or sachet, up to 81 mg. The UK 1% sachet is marked discontinued; Australia still has Testogel 1%. Irisel, another 16.2 mg/g gel in a pump, was first authorised in the UK on June 18, 2026. [10], [11], [57], [22], [12]
• Tostran 2% (UK): 10 mg per press, 60 mg a day on the abdomen or inner thighs, judged 2 hours after application. It is the same strength as the discontinued US Fortesta. [13]
• Testavan 2% (UK, Australia, France): 23 mg per press, spread with an applicator, from one to three presses. Ireland markets a 20 mg/g gel as Testarzon. [14], [15], [18], [58]

Fortesta: no longer sold in the US

Fortesta was a 2% gel for the front and inner thighs: 40 mg (4 presses) a day, adjustable from 10 to 70 mg, judged by blood drawn 2 hours after application. In its approval trial, 77.5% of men (100 of 129) were in range; skin reactions occurred in 16.1%. The brand was discontinued after a December 1, 2023 sponsor letter, not for safety reasons, and marketing of its only generic ended on January 31, 2026, so no 2% gel is sold in the United States (checked September 2026). Tostran is the nearest UK equivalent. [59], [60], [61], [62], [13]

Androderm patch: no longer sold

Androderm, approved on September 29, 1995, was a patch worn from night to night on the back, abdomen, upper arms or thighs: 4 mg/day to start, adjusted between 2 and 6 mg/day by an early-morning level, with 7 days before reusing a site. It copied the body's natural daily rhythm, but skin reactions affected 28% of men with the newer patches and 48% with older ones, and it had to come off before a magnetic resonance imaging (MRI) scan. It transferred far less testosterone to clothing than gel. It is no longer marketed in the United States (FDA found this was not for safety reasons) and was cancelled in Canada in 2021–22 (checked September 2026). [63], [64], [65], [66], [16]

Striant buccal system: no longer sold

Striant was a small tablet-like patch held on the gum above an incisor tooth, where testosterone passed through the lining of the mouth (buccal): 30 mg twice daily, about 12 hours apart. In its label trial, 86.6% of men were in range; gum or mouth irritation affected 9.2%, and levels fell below normal within 2 to 4 hours of removal. FDA withdrew its approval effective June 15, 2020, in a notice covering 16 applications, and no buccal testosterone is sold in the United States (checked September 2026). [67], [68], [69]

How should testosterone gel be stored?

Store it at room temperature, away from flames and out of reach of children and pets. Each product's label sets its own range. [4], [7]

[4], [1], [7], [8], [9], [10], [12], [13], [14], [22], [15]

The AndroGel labels give no separate time limit once a pump is opened. Used packets, tubes and pumps go in household trash where a child or pet cannot reach them. [4], [1], [7]

For carrying gel on a trip, see traveling with testosterone.

How can you keep testosterone gel off partners, children and pets?

Wash your hands with soap and water right after applying, let the gel dry, cover the site with clothing such as a T-shirt, and wash the site before skin-to-skin contact. Together, those steps prevented almost all transfer in the label studies. [4], [70]

Why is there a boxed warning?

Children have been harmed by touching a parent's gel. The labels describe children who developed an enlarged penis or clitoris, pubic hair, more erections and sex drive, aggressive behavior and bones that matured too fast. Most signs went away once the exposure stopped, but in a few, enlarged genitals did not fully return to normal size and bone age stayed ahead of the child's age. In some cases the precautions had not been followed. [4]

FDA announced the boxed warning on May 7, 2009, and it appeared in AndroGel's label that September. An FDA review counted 30 reports of secondary exposure with harm in children and adults between 2001 and 2009. The UK regulator repeated the warning in January 2023 after a UK report of a child with faster growth and genital enlargement from a parent's gel. In one published series, all 5 children exposed to a relative's gel were moderately to severely virilized; in another, the parents did not know their gel was the cause. [71], [72], [70], [73], [74]

Adult women can be affected too, with more body or facial hair, acne, a deeper voice or menstrual changes. Gel is contraindicated in pregnancy because testosterone can masculinize a female fetus. [75], [70], [4]

How much gel transfers, and what stops it?

The label studies used intense contact: a woman rubbing the man's application site for 15 minutes, hours after he applied the gel.

• Skin to skin. Two hours after 81 mg of AndroGel 1.62%, direct contact raised women's average testosterone by 280%. With AndroGel 1%, every unprotected partner in a 38-couple study reached more than twice her starting level. [4], [1]
• A T-shirt. With a T-shirt over the dried AndroGel 1.62% site, women's levels rose only 6%; with AndroGel 1%, a shirt prevented transfer completely. Clothing works best over the arms and shoulders: over 1.62% gel on the abdomen, an unapproved site, levels still rose 43–60%. [4], [1], [76]
• Washing the site. Washing the application site before contact brought partners' levels back to baseline. Without it, transfer was still seen at least 12 hours after application. [77], [76]
• Hands and clothing. Washing hands removed 96–99% of the residue. T-shirts worn over gel held a median 6,763 micrograms of testosterone, against 25 micrograms over a patch, and the 1% generic labels note a possible case of transfer through towels and sheets. [4], [8], [65], [50]

Doserly

Gel on a partner's skin: how much transfers, and what stops it

Rise in a female partner's testosterone after 15 minutes of rubbing the man's application site.

Skin to skinSite covered by a T-shirt

AndroGel 1.62%, 81 mg on shoulders and upper arms

Skin to skin +280%; with a T-shirt +6%. Contact 2 hours after applying, 8 and 12 couples, average level (Cavg).

AndroGel 1.62% on the abdomen (not an approved site)

With a T-shirt +43% (day 1) to +60% (day 7). T-shirt over the site, 16 couples, average level (Cavg).

Testosterone 2% solution, 120 mg in the armpits

With a T-shirt +13%. T-shirt over the site, 10 couples, total exposure (AUC).

Measured differently, so not on the scale

AndroGel 1%, 100 mg

Skin to skin: every partner rose above 2 times her starting level at some point. A shirt prevented transfer completely. 38 couples, daily contact 2–12 hours after applying.

Vogelxo 1%, 50 mg

Skin to skin: total exposure (AUC) 2.8 times her starting level. Shirt or washing the site: under 10% rise. 48 couples, contact 2 hours after applying.

What else the studies found

Washing hands

Removed 96–99% of the gel left on them.

Unwashed site

Still transferred at least 12 hours after applying.

Washing the site

Before contact brought partners back to baseline.

Wash hands, cover the dried site, and wash it before skin contact. The label studies used 15 minutes of deliberate rubbing.

What about pets?

The US labels say to dispose of used gel where pets cannot reach it, and the UK Irisel information says to cover the site to prevent transfer to other people "as well as pets". No study of pets exposed to human testosterone gel was found; keeping them off the site and off clothes worn over it follows the same logic as for children. [7], [12]

What should you do if someone is exposed?

Wash the area of contact on the other person with soap and water as soon as possible. If a child develops genital growth or pubic hair, or a woman develops new hair growth or acne, tell a doctor that someone in the home uses testosterone gel; the labels say to stop the gel until the cause is found. [4]

What does testosterone gel do to fertility, estrogen and red blood cells?

Each has its own guide; here is what is specific to gel.

Fertility. Gel lowers LH and FSH in proportion to the testosterone it adds, and the labels warn it may lower sperm counts, possibly to zero (azoospermia). In a contraception trial in healthy men, gel alone brought sperm to 1 million per mL or fewer in 23%: not a contraceptive, but a real suppression. The AUA says testosterone should not be prescribed to men trying to conceive, and the US male infertility guideline extends that to men interested in future fertility. See TRT and fertility. [2], [4], [78], [38], [79]

Estrogen and DHT. Some testosterone is converted to estradiol: on AndroGel 1%, estradiol rose within 30 days but stayed in the normal male range, and no guideline sets a routine estradiol target. Skin contains the enzyme 5-alpha reductase, so gel raises dihydrotestosterone (DHT) more than a patch: 3.6- to 4.6-fold against 1.3-fold. No study has linked gel's higher DHT to hair loss or prostate outcomes. See estrogen on TRT. [1], [2], [45], [38]

Red blood cells. In a network meta-analysis of 29 randomized trials, hematocrit rose about 3.0 percentage points more than placebo on gel, against 4.0 on enanthate or cypionate injections and 1.6 on long-acting undecanoate injections; only the difference between injections and patches was clear. In observational studies, hematocrit went above 50% in 12.8% of gel users vs 66.7% of injection users in one clinic, and in 25 of 498 gel users vs 69 of 304 on long-acting injections in one center's registry. US gel labels ask for hematocrit before treatment, 3–6 months after starting and then yearly. See hematocrit on TRT. [47], [80], [81], [4]

What do we actually know about testosterone gel in people?

That gel raises testosterone into the normal range in most men is settled; it is how gels were approved. What makes gel unusual is that the two biggest long-term testosterone trials, the Testosterone Trials and TRAVERSE, both used gels, so much of the long-term safety evidence for testosterone is gel evidence. [33], [82]

Which studies used testosterone gel itself?

Across the approval trials, 74–87% of men reached the normal range, so between about 1 in 8 and 1 in 4 did not at a given check, even with titration. [38]

Is gel as effective as injections?

No randomized trial has compared gel with injections on symptoms or long-term outcomes; a 2022 systematic review found hardly any direct comparisons. Both forms reach the normal range in most men, the Endocrine Society says high hematocrit is more common on injections (a pooled analysis of trials could not show a clear gap between gel and injections), and many men stop gel: in US claims data, of 15,435 men who started a topical product, 34.7% had kept filling it without a gap of more than 30 days at 6 months, and 15.4% at a year, though about half of those who stopped later restarted (the study did not include injection users). [84], [23], [47], [85]

How does testosterone gel work?

The gel is hydroalcoholic (made with alcohol and water). The alcohol carries testosterone into the outer skin and evaporates within minutes; a 2% gel dried in a median of 2.4 minutes. The skin then acts as a reservoir, releasing testosterone into small blood vessels for the rest of the day. That reservoir, not testosterone's own short life in the blood (10 to 100 minutes), sets the once-a-day schedule. [1], [86], [4]

In the blood, it acts like the body's own testosterone: about 40% is bound to sex hormone-binding globulin (SHBG), about 2% is free, and tissues convert some to DHT and estradiol. [4]

Why it switches off your own production. The brain senses testosterone from any source. When levels rise, the pituitary lowers its LH and FSH signals to the testicles, which then make less testosterone and fewer sperm. [2], [4]

What are the risks and unanswered questions?

Is testosterone gel safe?

For men with a confirmed diagnosis who follow the application rules and get regular blood tests, it is a standard, well-studied treatment with known risks: transfer to others, a rise in red blood cells, blood clots, higher blood pressure, prostate effects and loss of fertility. It has the best long-term heart-safety data of any form, because TRAVERSE tested it; safety beyond about two years remains less certain. [4], [82]

What side effects do the labels list?

In the 182-day AndroGel 1.62% trial, the reactions more common than on placebo were a rise in PSA (11.1%), emotional lability such as mood swings, impatience or anger (2.6%), high blood pressure (2.1%), a rise in hematocrit or hemoglobin (2.1%) and skin inflammation, mostly away from the application site (2.1%). Application-site reactions occurred in 0.9% of men (2 of 234). About 10.7% stopped because of side effects, most often a rising PSA. [4]

Skin reactions vary by product. The AUA gives 3–16% across topical products, the Fortesta trial found 16.1%, and in the AndroGel 1% trial skin irritation affected 5.5% of men on gel against 66% on a patch. The labels also list acne, breast enlargement (gynecomastia), fluid retention, sleep apnea and changes in cholesterol. [38], [59], [31], [4]

Does testosterone gel affect the heart?

The best evidence comes from TRAVERSE, a randomized trial of about 5,200 men aged 45 to 80 with heart disease or high heart risk, given daily AndroGel 1.62% or a placebo gel; the average dose was 65 mg a day. Among the 2,596 men who used testosterone gel and the 2,602 who used placebo gel, it found: [82], [4]

• Heart attack, stroke or heart death: 182 men (7.0%) on testosterone vs 190 (7.3%) on placebo; hazard ratio 0.96, with a 95% confidence interval of 0.78 to 1.17. The top of that range stayed below the trial's safety margin of 1.5, so a large rise in risk was ruled out. [82], [4]
• Heart rhythm: atrial fibrillation 3.5% vs 2.4%; nonfatal rhythm problems needing treatment 5.2% vs 3.3%. [4]
• Kidneys: acute kidney injury 2.3% vs 1.5%. [4]
• Clots: venous clots 1.7% vs 1.2%, including pulmonary embolism 0.9% vs 0.5%. [4]
• Fractures: 91 of 2,601 men (3.50%) vs 64 of 2,603 (2.46%), counting every randomized man. [87]
• Blood pressure: systolic pressure rose 1.0 mm Hg on testosterone and fell 0.5 mm Hg on placebo by 36 months. [4]
• Substudies: testosterone increased sexual activity and desire but not erections in men with low libido; it did not significantly slow progression from prediabetes to diabetes; mood and energy improved slightly more than on placebo, both in the 2,643 men with significant depressive symptoms and in the whole trial, but in the 49 men with persistent depressive disorder there was no clear difference, though that group was too small for a firm answer. [32], [88], [89]

Doserly

TRAVERSE: absolute results

Testosterone gel (2,596 men)Placebo gel (2,602 men)

Heart attack, stroke or heart death

Testosterone 7.0% vs placebo 7.3% (182 vs 190 men; hazard ratio 0.96, 95% CI 0.78–1.17; met the 1.5 safety margin)

Nonfatal rhythm problems needing treatment

Testosterone 5.2% vs placebo 3.3%

Atrial fibrillation

Testosterone 3.5% vs placebo 2.4%

Clinical fracture

Testosterone 3.5% vs placebo 2.5% (91 of 2,601 vs 64 of 2,603 in the full analysis set)

Acute kidney injury

Testosterone 2.3% vs placebo 1.5%

Venous clots (all)

Testosterone 1.7% vs placebo 1.2%

Pulmonary embolism

Testosterone 0.9% vs placebo 0.5%

About 5,200 men aged 45–80 at high heart risk; daily gel; mean treatment 21.7 months; about 61% stopped their study gel. Not a trial of injections.

Its limits. The average man used the gel for 21.7 months, about 61% stopped their study gel early, and everyone enrolled was at high heart risk, so it cannot speak to longer use or to lower-risk men. [82], [4]

Blood pressure. In a 16-week study with 24-hour monitoring, AndroGel 1.62% raised average blood pressure by 1.9/1.3 mm Hg, and by 3.0/2.2 mm Hg in men already treated for high blood pressure. Labels advise against gel with uncontrolled high blood pressure. [4], [90]

Gel compared with injections. In a study of 544,115 men starting testosterone in two US insurance databases and UK general-practice records, those starting injections had more heart attacks, unstable angina or strokes in their first year than those starting gel (hazard ratio 1.26, 95% confidence interval 1.18 to 1.35). It was observational, did not check whether the men needed testosterone and cannot prove cause. [91]

The AndroGel and Testim labels have carried the TRAVERSE results since July 2025, though the current Vogelxo and 2% solution labels did not yet include them; on every US gel label, the only boxed warning is about secondary exposure (checked September 2026). See TRT and heart health. [92], [4], [7], [8], [9]

What about blood clots, sleep apnea and fluid retention?

• Blood clots. Clots in the legs (deep vein thrombosis) and lungs (pulmonary embolism) have been reported with testosterone products; leg pain, swelling, warmth or redness, or sudden shortness of breath need urgent assessment. [4]
• Sleep apnea. Testosterone may worsen sleep apnea, especially with obesity or chronic lung disease. [4]
• Fluid retention. Swelling, with or without heart failure, can be serious in people with heart, kidney or liver disease. [4]

Could testosterone gel affect the prostate?

Testosterone can enlarge the prostate and raise PSA. In the AndroGel 1.62% trial, PSA rose by an average of 0.14 ng/mL over six months, against a fall of 0.12 ng/mL on placebo. In TRAVERSE, which excluded men with a PSA above 3.0 ng/mL, high-grade prostate cancer occurred in 5 of 2,596 men on testosterone (0.19%) vs 3 of 2,602 on placebo (0.12%), a difference that was not significant. US labels contraindicate gel in known or suspected prostate cancer and warn that men with an enlarged prostate may get worse urinary symptoms. See TRT and the prostate. [4], [93]

Is testosterone gel legal? Is it FDA approved?

Checked September 2026. Rules differ by country and change often.

United States. Testosterone gel is an FDA-approved prescription medicine and a Schedule III controlled substance. The key steps:

• Products. AndroGel 1% and 1.62%, Testim, Vogelxo, generic 1% and 1.62% gels and generic 2% solutions have current labels; Fortesta, Axiron, Androderm and Striant are no longer sold. [5], [62], [19]
• 2009 to 2016. FDA required the boxed warning on secondary exposure (2009), the statement that benefit in "age-related" low testosterone is not established (2015) and warnings on abuse and dependence (2016). [71], [92], [94]
• February 28, 2025. FDA told the makers of testosterone products to add the TRAVERSE results and blood-pressure warnings to their labels and to remove heart-risk language from boxed warnings. The AndroGel and Testim labels made these changes in July 2025. [92], [4], [7]
• June 18, 2026. The Department of Health and Human Services (HHS) announced that FDA is requesting label changes: removing the age-related limitation, contraindicating testosterone only in metastatic prostate cancer, and revising the prostate-enlargement warning. These are requests: the current gel labels still carry the old wording. [95], [4]
• Telehealth. Temporary rules let clinicians prescribe controlled medicines such as testosterone without an in-person visit through December 31, 2026; a permanent Drug Enforcement Administration (DEA) special-registration rule is still under review. [96], [97]

Canada. Schedule IV controlled substance, prescription-only. AndroGel 1%, Testim and Taro's 1% gel sachets are marketed, Taro's gel pump (approved September 18, 2026) is not yet, and no 1.62% gel is sold. [98], [16], [99]

United Kingdom. Class C controlled drug, prescription-only. Current gels are Testogel 16.2 mg/g, Irisel, Tostran and Testavan. [100], [101]

Australia. Schedule 4 (prescription-only), with extra controls on possession. Current topical products are Testogel 1%, Testavan and the AndroForte 5 cream. [102], [103]

European Union. Rules are national. France markets AndroGel 16.2 mg/g and Testavan, Ireland Testarzon 20 mg/g, and Spain the 50 mg Testogel sachet (1%), Testavan and Itnogen 20 mg/g, while Spain's Testogel 16.2 mg/g is authorised but not marketed; other member states were not checked. See TRT in Europe. [17], [18], [58], [104]

A "research use only" label or an overseas seller does not make a product legal, tested or the same as a licensed product.

Is testosterone gel banned in sport?

Yes. Testosterone in any form is on the World Anti-Doping Agency (WADA) Prohibited List in class S1, banned in and out of competition, and the 2027 list keeps that from January 1, 2027. Athletes with a medical need can apply for a therapeutic use exemption, which WADA grants only when low testosterone has an organic cause (such as a testicular or pituitary disorder), not for age, obesity or earlier steroid use. [105], [106], [107]

Who should be especially cautious?

• Men living with children or a pregnant partner. Transfer is the gel-specific risk, and pregnant women should avoid contact with the application site. [4]
• Men who want children now or soon. Testosterone suppresses sperm production; guidelines advise against it for men trying to conceive. [38], [79]
• Men with prostate or breast cancer. Contraindicated on current US labels (known or suspected prostate cancer). [4]
• Heart, kidney or liver disease, or uncontrolled high blood pressure. Fluid retention and blood-pressure rises can worsen these. [4]
• High hematocrit. Several guidelines treat a high starting hematocrit as a reason for caution. [23], [28]
• Sleep apnea. Untreated severe sleep apnea is a caution in guidelines and labels. [23], [4]
• Women and children. Testosterone gel is not for women (see testosterone therapy for women) and is not established for anyone under 18. [4]
• Drug-tested athletes. Banned at all times. [105]

Can testosterone gel be taken with other medicines?

The labels list three interactions:

• Blood thinners (oral anticoagulants). Testosterone can change their effect; the labels advise more frequent blood-clotting tests (the international normalized ratio, or INR, and prothrombin time), especially when starting and stopping testosterone. [4]
• Insulin and diabetes medicines. Testosterone can lower blood sugar and insulin needs. [4]
• Corticosteroids. Together they can increase fluid retention. [4]

Testosterone can also lower thyroxine-binding globulin, which changes total thyroid hormone results without changing thyroid function. Skin products matter too: antiperspirant affects the underarm solution, and moisturizer and sunscreen slightly increase absorption of AndroGel 1.62% (washing and lotions). Bring a full list of everything you take, including supplements, to a pharmacist or doctor. [4], [9], [27]

Is testosterone gel available, and what does it cost?

Checked September 2026.

In the United States, generic 1% and 1.62% gels are sold by several makers, and FDA's drug shortage data list no testosterone shortage (updated September 26, 2026). [5], [108]

There is no single US price. As a reference point, pharmacies paid on average about $0.47 per gram for generic 1.62% gel in September 2026, about $35 for 30 days at 40.5 mg (2.5 g) a day, and about $0.41 per gram for generic 1% gel packets, about $61 for 30 days at 5 g a day; brand Testim cost about $3.78 per gram. What you pay depends on the pharmacy and insurance. In Medicare Part D in 2024, the average gross cost was $167.85 per fill for that combined generic entry and $1,148.50 per fill of brand AndroGel, before rebates. [109], [6]

France's AndroGel 16.2 mg/g and Testavan are not reimbursed. For other countries, see the TRT access guides. [17], [18]

What should be monitored while using testosterone gel?

The US gel labels ask for testosterone, PSA, hemoglobin, hematocrit, liver tests, cholesterol and blood pressure to be checked periodically; the numeric limits come from guidelines. Use this summary to prepare questions for your prescriber; it is not a personal testing plan. [4]

[4], [23], [38], [24]

The European urology guideline monitors testosterone and hematocrit at 3, 6 and 12 months and then yearly. See TRT blood work and hematocrit on TRT. [28]

Write down the timing. For every testosterone result on gel, note the time you applied the gel that day (or that you had not yet applied it) and which arm the blood came from. A result without that context is hard to interpret. [4], [40]

What do people in public communities report?

Public forums hold every kind of gel story: men who feel better within weeks, men whose levels barely move after months, and men who stopped because of the daily routine, their skin or worry about their families. The accounts below come from public Reddit threads from the past year and are described without identifying anyone.

What do the positive reports look like?

Better energy, mood, sex drive and morning erections, sometimes within weeks. A man in his 20s on AndroGel 1.62% at 40.5 mg a day felt calmer and more energetic by his third week, then switched to injections only because he disliked the daily routine, and felt worse in the first weeks after the switch. A man in his 30s on 50 mg of AndroGel 1% noticed better mood, sleep and workout motivation within ten days. Another had felt well on 60 mg a day for years, until he raised the dose himself and developed erection problems within two months. [110], [111], [112]

Does everyone respond?

No, and "gel is not working" is a common topic. A man in his 40s went from 178 to 206 ng/dL after three months on one pump a day; his aches eased but his energy and sex drive did not, and he had sometimes put the gel on his thighs. A man in his 60s reported 280 before and 290 after seven months of AndroGel, and a man using one pump of 1.62% gel felt nothing after a month, with his level down from 13.3 to 11.3 nmol/L. A higher level did not always mean feeling better: one man reached 955 ng/dL on four pumps but felt little different from the 400s on two. [113], [114], [115], [116], [117]

Replies often suggest switching to injections. The labels point first to the basics: the product's own sites, the washing wait and when blood is drawn; after a genuine trial with low results, labels and the AUA support a dose change or another topical product. [4], [38]

Why do blood results confuse people?

Timing and contamination. One man's level came back at 96, below his pretreatment results, from blood drawn 24.5 hours after his last dose; another had missed the gel the day before his test. At the other extreme, a man on Tostran measured 10.3 nmol/L before his dose and 52.6 nmol/L three hours after it. With unexpectedly high results, one at 1,508 from an afternoon draw and one above 1,200 after gel on the forearms, contamination of the sample by gel on the skin was raised as a possible cause. These are the effects described in when blood should be drawn. [118], [119], [120], [121], [122]

What unwanted effects come up?

• Skin. Acne and irritation limited to the application sites, and stinging on very dry shoulders. Attempts to boost absorption made things worse: one person scrubbed dry skin with salicylic acid and a derma roller before applying and got burning, and another tore their skin removing an adhesive dressing put over the site to protect a partner and child. [123], [124], [125], [126]
• Off-label sites. One man's level jumped from 12.8 to 30.2 nmol/L after moving part of a larger dose to the scrotum, a site no US or UK gel label allows. [127]
• Hematocrit. One man's hematocrit rose from 40% to 50% within two months on 50 mg of Testogel, with fatigue and head pressure; two weeks after stopping, it was 48%. He was also losing weight on tirzepatide and unsure how well hydrated he had been. [128]
• Hair and testicles. A man in his 30s stopped Testogel after hair loss and testicular shrinkage; seven to eight months later his LH and FSH had recovered and his testosterone was back at the low end of the range. [129]
• Swings and new symptoms. Some describe a lift for a few hours after applying, then a dip. One man started by a clinic on 100 mg of AndroGel 1% reported a pounding heartbeat, headaches and faster breathing within days. [130], [131]

What do people say about family, cost and switching?

Transfer shapes decisions: one person with young children and a pet asked for injections before starting gel, and the prescriber switched the order to weekly cypionate. Costs and access vary: one wife reported $53 a month for her husband's gel, a man in Germany switched to injections mainly because gel was expensive, and a man in Australia said his general practitioner would prescribe only gel. [132], [133], [134], [135]

People switching to injections often ask for an equivalent dose, and replies point out that none exists; the new dose has to be judged by new blood tests. Some who switched felt worse within days, which replies called too early to judge. And a man thinking of using his wife's Testogel for an extra boost at the gym changed his mind after replies explained it would suppress his own production. [117], [136], [137]

How can you judge a gel story?

Ask: Which product and strength, and how many presses or mg? Where was it applied, and how long before washing? When was blood drawn relative to the day's application, and from which arm? What else changed at the same time, such as weight loss, sleep treatment, other medicines or training? What happened a few months later?

These selected discussions show what people experience and what research should answer. They are not a survey of all users, a success rate or a substitute for the studies.

How does testosterone gel compare with other testosterone forms?

These are the forms most often weighed against gel. Status was checked in September 2026.

No trial ranks these forms on long-term outcomes. The practical differences are how often you dose, how much levels swing and hematocrit rises, how quickly the form clears and whether someone else can be exposed. [84], [47]

Common questions about testosterone gel

How much testosterone gel should I use?

The labels start at 40.5 mg (2 presses) of a 1.62% gel or 50 mg of a 1% gel once each morning, then adjust by blood tests: 20.25–81 mg for AndroGel 1.62%, and up to 100 mg for 1% gels. The right number of presses depends on the product, so your prescription and label decide it. [4], [1], [7] See typical protocols.

How long after applying testosterone gel can I shower, swim or have sex?

Wait at least 2 hours after AndroGel 1.62%, Testim and most other gels, 5 hours after AndroGel 1%, and 1 hour after UK Testogel before showering or swimming. For skin-to-skin contact, cover the dried site with a shirt or wash it first, whatever the time; transfer was still seen 12 hours after application in one study. [4], [1], [10], [76] See washing and protecting others.

Can I put testosterone gel on my stomach, thighs or scrotum?

Only if your product's label names that site. AndroGel 1% may go on the abdomen, and Tostran on the abdomen or inner thighs, but AndroGel 1.62%, Testim and UK Testogel are for the shoulders and upper arms only; abdominal application of 1.62% gel gave 30–40% lower exposure. No US or UK gel is labeled for the scrotum, where absorption is far higher. [1], [13], [4], [37], [51] See application sites.

Is testosterone gel as good as injections?

No trial has compared them head to head on symptoms or long-term outcomes. Both bring most men into the normal range; gels give steadier daily levels and, according to the Endocrine Society, are less likely to push hematocrit too high (a pooled analysis of trials could not show a clear gap), while injections are cheaper, do not transfer to others and are not a daily task. [84], [23], [47], [30] See the evidence.

How do I switch from gel to injections, and what dose is equivalent?

There is no validated conversion between a gel dose and an injection dose, because only a variable part of the gel is absorbed. Prescribers start the new form at its own labeled or guideline dose and check blood levels afterward. [4], [1], [84] See stopping and the cypionate guide.

Why is my testosterone still low on gel?

Common reasons are blood drawn before the day's dose (the lowest point), a missed application, washing too soon, an unlisted site, or simply absorbing less than average; in trials, about 1 in 8 to 1 in 4 men were outside the normal range at a given check. Labels respond by adjusting the dose, and switching brands raised levels in some men. [4], [38], [44] See blood-test timing.

Does testosterone gel cause hair loss?

It may. Gel raises DHT, the hormone behind male-pattern hair loss, more than a patch does, and the labels list hair loss (alopecia) among reactions reported after approval, but no study has shown that gel causes more hair loss than other forms. [2], [45], [4] See estrogen and DHT.

Glossary

Plain explanations of the medical, dosing and research terms used in this guide. Underlined terms in the text link here.

5-alpha reductase

An enzyme, found in skin and the prostate, that turns testosterone into DHT. It is why gel raises DHT more than a patch does.

Adverse event

A harmful or unwanted medical event reported after someone used a treatment. A report alone does not prove the treatment caused it.

Azoospermia

No sperm at all in a semen sample.

Bioequivalence

When two products deliver the same drug into the blood at the same rate and amount, within set limits (usually 80–125%). Testim and AndroGel are not bioequivalent.

Boxed warning

The most serious warning FDA puts on a US label, printed in a box at the top. Testosterone gels carry one about secondary exposure of children.

Buccal

Absorbed through the lining of the mouth, as with the discontinued Striant, which was held against the gum.

Controlled substance

A medicine whose prescribing and possession are restricted by law because it can be misused. Testosterone is Schedule III in the US, Schedule IV in Canada and Class C in the UK.

Controlled trial

A study that compares people who receive a treatment with a similar group who do not, often receiving a placebo instead. Randomly assigning people to each group makes the comparison fairer.

DHT (dihydrotestosterone)

A stronger hormone made from testosterone by 5-alpha reductase. It drives male-pattern hair growth and loss and prostate growth.

Ester

A chemical tail joined to testosterone in injectable forms, such as cypionate, that makes it release slowly from oil. Gel contains plain testosterone with no ester.

Estradiol

The main form of estrogen. In men it is made mostly from testosterone, so it rises when testosterone rises.

FSH (follicle-stimulating hormone)

A pituitary hormone that acts on the cells supporting sperm production. Testosterone therapy lowers it.

Gynecomastia

Growth of breast tissue in men, often tender at first. It is linked to a higher estrogen-to-testosterone balance.

Hematocrit

The share of the blood made up of red blood cells. Testosterone raises it, and most guidelines act when it reaches about 54%.

Hypogonadotropic hypogonadism

Low testosterone because the brain and pituitary send too little LH and FSH to the testicles. It can be present from birth or start later. Also called secondary hypogonadism.

Hypogonadism

Low testosterone caused by a problem in the testicles or in the brain and pituitary signals that control them, confirmed with symptoms and repeated morning blood tests.

LH (luteinizing hormone)

A pituitary hormone that tells the testicles to make testosterone. Testosterone therapy lowers it, often a lot.

MACE (major adverse cardiovascular events)

A combined measure used in heart-safety trials. In TRAVERSE it meant heart attack, stroke or death from heart disease.

Placebo

A dummy treatment with no active ingredient, used as a comparison in studies. In TRAVERSE, the placebo was a gel without testosterone.

Pre-dose level

A blood test taken in the morning before that day's gel, when levels are at their lowest. The US AndroGel 1.62% and Testim labels adjust the dose by it.

Primary hypogonadism

Low testosterone because the testicles themselves do not work well, even though the pituitary sends plenty of LH and FSH.

PSA (prostate-specific antigen)

A blood test for a protein made by the prostate. It rises slightly on testosterone and is used to decide whether prostate checks are needed.

Pump press (actuation)

One full push of a metered gel pump. The amount per press depends on the product: 20.25 mg for 1.62% gels and 12.5 mg for 1% gels.

Secondary exposure

Testosterone reaching someone other than the patient, usually by touching skin or clothing where gel was applied.

SHBG (sex hormone-binding globulin)

A blood protein that carries testosterone. Testosterone bound to it is not immediately available to tissues, so SHBG affects how much free testosterone there is.

Steady state

The point, after a few days of daily use, when levels follow the same pattern each day. For testosterone gel it is reached in about 2 to 3 days.

Subcutaneous (SC)

Injected into the fatty layer just under the skin, as with the Xyosted autoinjector.

Titration

Adjusting a dose in steps, usually based on blood tests and symptoms.

Transdermal

Absorbed through the skin into the blood, as with gels, solutions and patches.

TRT (testosterone replacement therapy)

Prescribed testosterone, by gel, injection or other forms, for men with low testosterone. It lowers the brain's LH and FSH signals, which can reduce or stop sperm production.

Virilization

Development of male traits, such as genital growth, pubic or facial hair and a deeper voice, in a child or woman exposed to testosterone.

WADA

The World Anti-Doping Agency, which publishes the list of substances banned in sport. Testosterone is banned at all times.

Weekly total

All the amounts given in one week, added together. For gel it is the amount applied, of which only a small share is absorbed, so it cannot be compared with an injection's weekly total.

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: product labels and product information from the United States, the United Kingdom, Canada, Australia and Europe, clinical guidelines, published clinical trials and studies, FDA and Federal Register records, and regulatory and price databases. We also reviewed public online forums where people describe their own experiences with testosterone gel.

The guide cites 143 sources, including 29 product labels and product information documents, 10 clinical guidelines and 41 original studies and case reports in people, plus 28 public community threads. Each type of source answers a different question. Labels, guidelines and trials show what was approved and measured. Regulatory records show what is sold and what changed. Personal accounts show what individual people experienced. Every numbered citation links to its entry below, labeled by source type.

How this guide was made

Research and drafting were AI-assisted. Every cited source was checked against the original, and the guide was reviewed and edited by Doserly before publication. It has not had an independent clinical review, and Doserly does not currently have medical reviewers. Doserly makes a medication and health-tracking app and runs Doserly Academy, both of which are promoted in this guide. Read our editorial policy for how guides are researched, updated and corrected.

This guide is for educational purposes. It summarizes what the reviewed sources report so the research is easier to understand; it is not medical advice. For a deeper dive, or to check any point for yourself, go straight to the cited sources.

Explore the sources