Starting TRT: The Definitive Guide

What happens when you start TRT?

Starting testosterone replacement therapy (TRT) means beginning prescribed testosterone after blood tests confirm that your testosterone is low and you have symptoms that fit. The first three months work like a trial. You have baseline checks, take the first doses, get a follow-up blood test timed to your form of testosterone, and then review with your prescriber whether your symptoms actually improved. [2], [3]

Before any prescription, US labels require low morning testosterone on at least two separate days. The American Urological Association (AUA) uses 300 ng/dL as its cut-off, and a July 2026 Endocrine Society statement also points to about 300 ng/dL on at least two early-morning fasting tests. The low testosterone guide covers diagnosis in full. [1], [2], [22]

In the US, testosterone is approved for men whose low testosterone has a medical cause, such as a problem in the testicles or the pituitary gland (hypogonadism). The labels still say its safety and benefit in "age-related" low testosterone have not been established. In June 2026 the US Food and Drug Administration (FDA) asked makers to remove that line, but no label has changed yet (checked September 2026). [23], [1], [24], [21]

Three things change in the first weeks, each at its own speed:

• Your blood level. Gel brings testosterone into the normal range on the first day; injections take several doses to settle (see why changes arrive at different times). [6], [2]
• Your own production. Testosterone from outside tells the brain to turn down its signals to the testicles, so the testicles make less of their own testosterone and fewer sperm. [10], [1]
• Your blood. Red blood cells start to increase within the first month. [11]

How you feel changes more slowly and less predictably. A review of placebo-controlled trials done for the Endocrine Society found small improvements in sexual desire, erections and sexual satisfaction, and no clear effect on energy or mood. That is worth knowing before the first dose. [25]

This guide covers men starting TRT. The TRT overview compares all the forms, and the TRT dosage guide covers dose schedules in depth.

Starting TRT: the key numbers

This table shows when each major clinical guideline rechecks testosterone and hematocrit (the share of the blood made up of red cells) after TRT starts, where in the dosing cycle the sample is taken, and what testosterone level it aims for. When each one judges symptoms is in the stopping rules. The numbers are what each document says, checked in September 2026.

[2], [3], [4], [15], [14], [16], [26], [17]

Most guidelines recheck testosterone and hematocrit about 3 to 6 months after starting and judge symptoms somewhere between 3 and 12 months. They differ on the exact month, on whether blood for injections is drawn midway between doses or at the trough, and on the target, which runs from 14–17 nmol/L in Canada to 15–30 nmol/L in the BSSM guideline. [3], [14], [15]

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When is the first testosterone recheck after starting?

Weeks after the first dose, by form (AUA guideline and product labels) and by guideline.

By form

1. 2–4 weeks

   Gels and nasal gel (AUA guideline).

2. About day 14 and day 28

   AndroGel 1.62% (US label): morning level before that day's dose.

3. At least 7 days after starting or a change

   Jatenzo oral capsules (US label): 6 hours after the morning dose.

4. 3–4 weeks

   Tlando oral capsules (US label): 8–9 hours after the morning dose.

5. From 1 month

   Natesto nasal gel (US label).

6. After 6 weeks

   Xyosted weekly autoinjector (US label): trough, 7 days after the last dose.

7. After 3–4 injections

   Cypionate or enanthate (AUA guideline): set by dose count, not a fixed week.

By guideline

1. 3 months

   EAU (2026) and CUA (2021).

2. 3–6 months

   Endocrine Society (2018) and VA (2026).

Aveed: the AUA checks halfway between the first two 10-week injections. Your prescriber's timing may differ.

When do the product labels check first?

Some labels set their own first check with a dose rule tied to it: the Xyosted autoinjector checks a trough after 6 weeks and moves the dose in 25 mg steps, AndroGel 1.62% checks at about 14 and 28 days, the oral capsules check hours after a morning dose (Tlando at 3–4 weeks, with no dose changes), and Natesto from 1 month. Plain cypionate and enanthate vials give no timing, so the guidelines above apply. [5], [27], [28], [29], [1]

Why do guidelines disagree?

Mostly because the evidence behind each choice is thin, and the guidelines grade it that way themselves. The AUA rates its 450–600 ng/dL target a conditional recommendation (Grade C), the BSSM rates its 15–30 nmol/L target at evidence level 4 (Grade C), and the CUA rates the evidence for its 14–17 nmol/L target low and its recommendation weak. [2], [15], [14]

Timing is the other big difference. A test drawn midway between injections reads higher than one drawn at the trough, just before the next dose, so a trough-based guideline and a midway-based one can read the same man differently. Gels and oral capsules are tested a set number of hours after a dose instead. The TRT blood work guide explains each draw time.

The first recheck also has a practical purpose: the starting dose often changes. The Endocrine Society says "multiple dose titrations are usually necessary" to keep testosterone in range, and in US insurance claims for gel, dose increases appeared as early as the first month. [3], [35]

How do the units work?

US labs report testosterone in ng/dL; most other countries use nmol/L. One nmol/L equals 28.84 ng/dL, so 300 ng/dL is about 10.4 nmol/L and 600 ng/dL about 20.8 nmol/L. The testosterone unit converter switches between them.

Why do changes arrive at different times?

Because the blood level, your own hormone production and each body system respond on different clocks. The form of testosterone sets how fast the blood level settles, and each tissue then responds at its own pace. [8]

How fast do blood levels settle?

It depends almost entirely on the form.

• Gels. In a trial of 227 men, gel brought testosterone into the normal adult range on the first day. The AndroGel 1% label says levels are close to steady state (the point where each dose replaces what the body clears, so levels stop climbing) by the end of the first 24 hours and at steady state by day 2 or 3. [6], [36]
• Weekly enanthate autoinjector. The Xyosted label reports steady state by week 6, and a dosing study found exposure matched after the third weekly 100 mg injection. [5], [37]
• Cypionate and enanthate injections. Testosterone is joined to a chemical tail (an ester) and dissolved in oil, so it releases slowly from a pool of oil in the muscle (a depot). The US cypionate label gives a half-life of about 8 days, and on the Azmiro label levels peaked a median of 71.7 hours after a 200 mg dose. The AUA does not check these injections until after 3–4 doses. [1], [38], [2]
• Long-acting undecanoate injection. On the Aveed label, levels peak a median of 7 days after an injection, and steady state arrives with the third injection, at 14 weeks. [32]

Testosterone itself lasts only minutes in the blood; the enanthate label gives a half-life of 10 to 100 minutes. The multi-day figures describe slow release from the oil, not the hormone. We found no study measuring exactly when weekly or every-2-week intramuscular (into a muscle) cypionate levels stop changing. [34]

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How long each form takes to reach a steady blood level

Time after the first dose, as stated on the label or measured in a dosing study.

1. Gel: Day 1 to day 2–3

   A trial of 227 men reached the normal range on day 1. The AndroGel 1% label: near steady state by 24 hours, steady state by day 2–3.

2. Weekly enanthate autoinjector: By week 6

   Xyosted label: steady state by week 6. A dosing study found exposure matched after the 3rd weekly 100 mg dose.

3. Cypionate injection: Not established

   No steady-state time on the label. Half-life about 8 days (label); the AUA checks after 3–4 injections.

4. Long-acting undecanoate injection: Week 14

   Aveed label: peak a median 7 days after each injection; steady state with the 3rd injection, at week 14.

Testosterone itself lasts minutes in the blood; the days and weeks come from slow release from the gel reservoir or the oil depot.

What happens to your own testosterone and sperm?

Your own production is turned down from the first doses. The brain reads the extra testosterone as "enough" and lowers LH (luteinizing hormone) and FSH (follicle-stimulating hormone), the two pituitary signals that drive the testicles. In healthy men given enanthate 200 mg weekly for three weeks, LH fell to 5% of its starting level and testosterone inside the testicles fell by 94%. [10]

Sperm production depends on that high level inside the testicles, normally about 40 to 100 times the level in the blood. That is why the labels warn that testosterone lowers sperm production and that reduced fertility may not always reverse. The TRT and fertility guide and the hCG guide cover ways to protect it. [39], [40], [1]

Why do red blood cells rise?

Testosterone makes the bone marrow produce more red blood cells, and the rise depends on the dose: in a study of healthy young and older men given graded doses, hemoglobin and hematocrit rose in step with the dose, more in older men, starting within a month and in many men still rising after week 12. The hematocrit guide explains why and what guidelines do about it. [11], [3]

What does the research show about the first 3 months?

Each outcome has its own timetable. Sex drive moves first, erections and mood take weeks, energy is the least consistent, and body composition and bone take months. Most of the week-by-week detail comes from small open studies (no placebo group) and a narrative review; placebo-controlled trials mostly measured at 3 months or later. [7], [8], [41]

What changed, and when, in the studies?

Sex drive usually moves first and bone last. Energy is the change trials find least reliably. [8], [9], [25]

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What studies saw change in the first months of TRT

Week each change was first seen or levelled off; each row names its study.

1. By week 3without placebo

   Sex drive and sexual thoughts levelled off (open study, injections).

2. Weeks 3–6without placebo

   Sexual interest from week 3, levelled off by week 6 (review of studies).

3. By day 30without placebo

   Sexual function and mood at their best on gel (gel trial, no placebo).

4. Week 6 (mood weeks 6–9)without placebo

   Depressive symptoms levelled off at week 6; good mood at weeks 6–9 (open study).

5. Over 9 weekswithout placebo

   Total erections rose to a peak (open study).

6. Weeks 9–12without placebo

   Fatigue improved (open study).

7. By day 90without placebo

   Leg strength, lean and fat mass changed on gel; no further strength gain by day 180 (gel trial, no placebo).

8. 3 monthsplacebo-controlled

   Sexual desire, erections and activity better than placebo at the first time measured (Testosterone Trials).

9. Month 1 onwardwithout placebo

   Hematocrit starts rising within the first month and is often still rising after week 12 (graded-dose study).

10. After 6 monthswithout placebo

    Bone changes (review; trial in severely deficient men).

Each point comes from one study; no curve joins them. Most early detail is from small open studies, and individual timing varies.

What do the placebo-controlled trials add?

They confirm the order but shrink the size of most changes. Sex drive is the most consistent: in the Testosterone Trials, desire, erectile function and sexual activity were better than on placebo at 3 months and stayed that way for the year. Erections improve less than desire: pooled trials put the gain at about 2 points on the International Index of Erectile Function (IIEF), TRAVERSE found no better erections, and in T4DM only 3 more men in 100 than on placebo had a meaningful gain. [41], [43], [44], [51]

Mood improves a little: a meta-analysis of 27 randomized trials found a small drop in depressive symptoms (effect size 0.21). Energy is uncertain: no vitality gain in the Testosterone Trials, a subgroup-only result in a 12-week trial of a 2% solution, and modest gains in TRAVERSE. Strength and body composition move by 3 months: in a 227-man gel trial, leg-press strength rose 11–13 kg by day 90 with no further gain by day 180, and lean mass rose 1.3–2.7 kg while fat fell by about 1 kg. [45], [9], [42], [46], [47] The guides on sexual health, mental health and muscle and fat loss go further.

Does everyone respond?

No. In one urology practice, 70% of 127 men reported better erections, sex drive, energy or mood by 3 months, and 63% finished a year with benefit. About 27% stopped because they felt no major benefit, and nearly two-thirds of those (64.7%) had reported nothing by 3 months. This was a look back at one practice's records, so it cannot predict any one man's result. [52]

In the Testosterone Trials, bigger rises in testosterone went with more sexual activity and desire, but no testosterone level worked as a threshold, and nothing measured at the start predicted who would respond. [41]

How many men are still on TRT after a year?

Fewer than you might expect, and the numbers depend heavily on how "stopping" is defined.

• In US insurance claims for 15,435 men starting gel, 34.7% were still filling prescriptions at 6 months and 15.4% at 12 months; about half of those who stopped later restarted. [35]
• In another claims study of 3,184 men starting gels, 17% were still taking it as prescribed at 12 months. [53]
• Among 4,797 Ontario men aged 66 or older, the median time to stopping was 319 days on gels and 283 days on injections. [54]
• In TRAVERSE, about 61% of men stopped their study gel early, whether it held testosterone or placebo. [55]
• In a survey of 382 men on TRT at one US clinic, 70% were satisfied and 14% dissatisfied; 35% of injection users said they chose injections for the lower cost. [56]

Each study counted stopping differently, so the figures cannot be compared or combined. No study we found broke down, across forms, why men stop in the first year.

Is starting TRT safe?

It is an approved medicine with well-described risks, which is why guidelines check blood at the start and again within months. In the largest safety trial, heart attacks, strokes and heart deaths were no more common on gel than on placebo over about two years, within the trial's safety margin, but there were more heart-rhythm problems, kidney injury, lung clots and fractures, and the first months bring predictable changes: fewer sperm, more red cells and slightly higher blood pressure. [57], [55], [58], [12]

What did TRAVERSE show about heart safety?

TRAVERSE randomized 5,204 men aged 45 to 80 with low testosterone and existing heart disease or high heart risk to daily testosterone gel or placebo gel. MACE, a combined measure of heart attack, stroke or death from heart disease, occurred in 7.0% of men on testosterone and 7.3% on placebo (hazard ratio 0.96), which met the trial's safety goal: 182 of the 2,596 men who took testosterone and 190 of the 2,602 who took placebo. The 95% confidence interval ran from 0.78 to 1.17, so a large rise in risk was ruled out, though a small one was not. [57], [55]

Some problems were more common on testosterone: atrial fibrillation 3.5% vs 2.4%, acute kidney injury 2.3% vs 1.5%, and pulmonary embolism 0.9% vs 0.5%. Clinical fractures were also more common, 3.50% vs 2.46%. [55], [58]

The trial has limits. It tested only a daily gel, men used it for an average of 21.7 months, about 61% stopped their study gel early, and everyone enrolled was at high heart risk. [57], [55] The TRT and heart health guide covers it in full.

The AUA asks clinicians to tell men that low testosterone is itself a risk factor for heart disease, and to tell men on treatment to report chest pain, shortness of breath, dizziness or fainting. [2]

What side effects show up in the first weeks?

Mostly local and predictable ones. For intramuscular injections, the Endocrine Society lists pain at the site, swings in mood or sex drive, and coughing fits straight after an injection. [3]

• Injection-site reactions. In a 26-week study of the Xyosted autoinjector, 4 of 133 men had bruising and 6 had bleeding at the site, and one man reported mild pain across 965 assessed injections. In 63 transgender men using weekly subcutaneous (into the fatty layer under the skin) injections, 9 had minor, short-lived reactions. After the large-volume undecanoate injection, 80% of men reported pain, which was back to normal by day 4. [59], [60], [61]
• Oil reactions. The Aveed label carries a boxed warning for pulmonary oil microembolism (oil droplets reaching the lungs, causing coughing or breathlessness) and severe allergic reactions, with 30 minutes of observation after every injection; one analysis counted 28 microembolism reports against 90,092 doses distributed. Two case reports traced severe allergy to depot undecanoate to ingredients in the oil. [32], [62], [63], [64]
• Sleep and breathing. At high research doses, sleep shortened by about an hour and breathing during sleep worsened within 3 weeks in 17 healthy older men; in obese men with severe sleep apnea, oxygen drops at night worsened at 7 weeks but not at 18. No study we found looked at sleep in the first weeks at usual replacement doses. [65], [66]
• Skin, breast tenderness and fluid. Common complaints, but we found no trial giving first-3-month rates with clear denominators; see the TRT side effects guide.
• Gel transfer. All US gels and solutions carry a boxed warning about secondary exposure: testosterone rubbing off onto other people, with early puberty-like changes reported in children. [27]

Pain that spreads from an injection site, a hot swelling with fever, or coughing and breathlessness straight after an injection needs prompt medical attention.

Who should be especially cautious?

• Men who want children now or soon. The AUA says testosterone should not be prescribed to men trying to conceive, and the AUA and the American Society for Reproductive Medicine say clinicians should not prescribe it to men interested in current or future fertility. The Endocrine Society advises against it for men wanting fertility in the next 6–12 months and suggests considering sperm banking if unsure. [2], [67], [3]
• Men with a recent heart attack or stroke. Guidelines wait before starting: the AUA 3–6 months, the Endocrine Society 6 months and the VA 4 months. Uncontrolled heart failure is a reason not to start. [2], [3], [16]
• Men with a high hematocrit before starting, above 48–50% under most guidelines (see before the first dose). [3], [2]
• Men with untreated severe sleep apnea, a clotting disorder (thrombophilia), breast or prostate cancer, a prostate nodule, a PSA above 4 ng/mL without a urology check, or severe urinary symptoms. The Endocrine Society and the VA list these among reasons not to start. [3], [16]
• Men taking insulin, blood thinners or corticosteroids (see interactions).
• Drug-tested athletes. Testosterone is banned in sport at all times, and an exemption is granted only for low testosterone with an organic cause, such as testicular or pituitary disease, not for age, weight or past steroid use. [20], [68]
• Under-18s. Testosterone for teenagers belongs only in specialist care.
• Women. This guide is written for men. Testosterone for women uses different products and far smaller doses; see testosterone therapy for women.

Which medicines interact with testosterone?

The US labels name three: testosterone can lower blood sugar and so reduce insulin needs in men with diabetes; it can change the effect of blood thinners such as warfarin, so the clotting test (INR) should be checked more often; and taken with corticosteroids it can add to fluid retention. [27]

Some diabetes medicines called SGLT2 inhibitors raise hematocrit on their own, which adds to the rise on testosterone; the hematocrit guide has the numbers. The TRT with GLP-1 medicines guide covers weight-loss medicines. Bring a full list of what you take, including supplements, to your prescriber or pharmacist. Checked September 2026.

Is TRT legal, and does it count as doping?

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

• United States. Testosterone and its esters are Schedule III controlled substances. A Schedule III prescription cannot be filled or refilled more than 6 months after it was written, or refilled more than 5 times. Temporary telehealth rules let clinicians prescribe it without an in-person visit through December 31, 2026; a DEA rule creating a special registration for telehealth prescribing reached White House review in August 2026 and has not been published. No proposal to remove testosterone from Schedule III has been published. [18], [19], [69], [70]
• US labels. The FDA's June 2026 requests (removing the age-related limitation and narrowing the prostate cancer contraindication) are requests, not yet in any label. [21], [23]
• United Kingdom. Testosterone is a Class C controlled drug. [71]
• Canada. Testosterone is a Schedule IV controlled substance. [72]
• Australia. Testosterone is a Schedule 4 prescription-only medicine. [73]
• Sport. The World Anti-Doping Agency (WADA) prohibits testosterone at all times, and its 2027 list, published in September 2026, keeps the ban. [20], [74]

Access, coverage and costs differ by country; see the guides for the United States, the United Kingdom, Canada, Australia and the European Union.

What do guidelines say to do before and after starting?

Confirm the diagnosis and its cause, check a few safety markers, talk about fertility, then recheck at a time that matches the form and review symptoms after a few months. This section describes what guidelines ask clinicians to do; it is not a personal plan. [2], [3]

What happens before the first dose?

[1], [2], [3], [22], [4], [16], [67]

The low testosterone guide, the TRT blood work guide and the guide to raising testosterone naturally cover these steps in depth.

How often are these steps skipped?

Often. The AUA notes that up to 25% of men prescribed testosterone were not tested before starting, and nearly half were not rechecked after. [2]

• In US insurance claims for 61,474 men aged 40 or older (2001–2010), only 52.4% had a testosterone test and 43.3% a PSA test in the year after starting. [75]
• In 142 new starts in the VA health system, 47.2% had no testosterone test and 39.4% no hematocrit within 6 months. [76]
• When researchers posed as a man with normal testosterone who wanted children, 6 of 7 US direct-to-consumer platforms offered him testosterone, only 1 of 7 asked about recent heart problems or fertility, and 5 of 6 did not discuss the risk of a high red-cell count. [77]

The AUA also advises commercially made testosterone over compounded products when possible. [2]

What happens at the first follow-up?

The prescriber compares a correctly timed testosterone level with the target, checks hematocrit, and usually asks about symptoms and side effects. PSA and blood pressure are checked on schedules that differ by guideline (see what to track). [3], [14], [16]

Dose changes at this point are normal, not a sign of failure. Labels that set a first check also set a rule: Xyosted moves in 25 mg steps, AndroGel 1.62% adjusts to stay within 350–750 ng/dL, and Tlando has no dose changes at all. The Endocrine Society refers a man to urology if PSA rises by more than 1.4 ng/mL in the first 12 months. [5], [27], [28], [3]

When do guidelines say to stop if it is not helping?

When testosterone is back in range but the symptoms that started the treatment have not improved. The AUA puts it plainly: "There is no utility in continuing testosterone therapy in men who achieve target testosterone levels without symptom/sign improvement." [2]

[14], [2], [3], [15], [16], [17]

The disagreement is real. Most bodies treat the first months as a test of whether testosterone helps you; the UK Society for Endocrinology treats a confirmed diagnosis as a reason for lifelong replacement. The stopping TRT guide explains what happens to your own hormones and sperm after stopping.

Your first weeks: practical questions

How will the first injection feel?

It depends on the form and the volume: in studies, pain ranged from rare with a small weekly autoinjector dose to common, lasting up to 4 days, after the large-volume undecanoate injection (see side effects). US cypionate labels say intramuscular use only, deep in the buttock muscle, and the Xyosted label says not to inject until you have been trained. [59], [61], [1], [5] The injection guide covers sites, needles and technique.

Why don't I feel anything yet?

Because the first weeks are mostly about the blood level catching up. Gel reaches the normal range on day 1, but the earliest symptom changes measured in studies appear at about 3 weeks, and injected testosterone takes several doses to settle. Many men notice little in week 1 or 2, and that says little about the result at 3 months. [6], [7], [8], [5]

We found no study measuring symptoms in the first week, so reports of an early "honeymoon" or a crash after it come from personal accounts, not trials (see what people report).

Is 100 mg a week a normal starting dose?

For cypionate or enanthate injections, yes: 100 mg weekly appears in the AUA and Endocrine Society examples. The Endocrine Society lists 75–100 mg weekly or 150–200 mg every 2 weeks, and the AUA prefers 100 mg weekly over 200 mg every 2 weeks or 300–400 mg monthly. The US labels allow a wider 50–400 mg every 2–4 weeks. Xyosted starts at 75 mg weekly, and AndroGel 1.62% at 40.5 mg a day. [3], [2], [1], [5], [27]

Read the units. A dose is written in milligrams, but you draw a volume. At 200 mg/mL, 100 mg is 0.5 mL, which is 50 units on a U-100 insulin syringe; at 100 mg/mL, the same 100 mg is 1 mL. The TRT dose calculator does this arithmetic for any strength and schedule, and the TRT dosage guide compares schedules. [1]

These are labeled and guideline doses; prescribers adjust them using blood tests and symptoms. They are for adult men. For women, see testosterone therapy for women.

Is a bigger first "loading" dose normal?

Not on the cypionate or enanthate labels, which contain no loading dose; we found no trial testing one. The only labeled shortcut is for the long-acting undecanoate injection: Aveed gives its second dose at week 4 instead of week 10, and Nebido allows a first interval as short as 6 weeks. [1], [34], [32], [33]

Why is my testosterone so high on a low dose?

Men respond very differently to the same dose. The Endocrine Society notes "considerable variation" in testosterone levels among men on the same treatment, and that "a small fraction" of men develop levels above the normal range on intramuscular injections. [3]

Before reading much into one result, check when it was drawn: on the Azmiro label, levels peak about 3 days after a 200 mg dose, so a sample taken then reads far higher than one taken just before the next dose. We found no study that defines "hyper-responders" as a group. The blood work guide explains the timing. [38]

Do I need an aromatase inhibitor or hCG from the start?

Not routinely, according to the guidelines. The AUA recommends an estradiol test before treatment for men with breast growth or breast symptoms and makes it optional for others, and the VA does not generally recommend aromatase inhibitors (medicines such as anastrozole that block estrogen production) because of links with heart events, belly fat and bone loss. In older men with low testosterone, a year of anastrozole lowered spine bone density compared with placebo. [2], [16], [78]

hCG is a fertility question, not a routine add-on. The AUA says clinicians may use hCG, aromatase inhibitors or SERMs (tablets such as clomiphene that raise the body's own LH and FSH) to help keep fertility, noting that only hCG is FDA-approved for men, and the VA reserves hCG for men with pituitary-type low testosterone who want children. See the hCG, estrogen on TRT and TRT and fertility guides. [2], [16]

What if I miss a dose?

Ask your prescriber or pharmacist. None of the US patient leaflets we checked (Xyosted, AndroGel 1.62%, Jatenzo, Kyzatrex, Tlando and Natesto) gives a missed-dose rule. UK leaflets differ: the Testogel and Tostran gel leaflets say not to double up and to apply the next dose at the usual time, the Sustanon leaflet says to talk to your doctor or nurse, and the Nebido leaflet says not to miss injection appointments. [79], [5], [27] The travel guide covers doses across time zones.

How soon does hematocrit rise?

Within the first month in many men, and it can keep rising after month 3. In a 26-week study of weekly Xyosted, 10 of 133 men (7.5%) reached 52% or more; in the records of a UK clinic whose patients mostly used subcutaneous injections, often with hCG, about 1 in 4 (24.15%) passed 54% within 12 months, with no comparison group. [11], [59], [80] The hematocrit guide covers what guidelines do next.

Should I use a symptom questionnaire?

As a personal log, it can help; as a test, no. The AUA does not recommend validated questionnaires either to decide who should get testosterone or to monitor the response to it. The ADAM questionnaire picked up 88% of men with low testosterone but also flagged many men without it (specificity 60%). [2], [81]

Trials rated symptoms with structured questionnaires at set times, such as every 3 months in the Testosterone Trials. In an uncontrolled study of 1,174 men, Aging Males' Symptoms scores fell 32% over 12 weeks, which cannot separate the medicine from expectation. A simple, consistent log of sex drive, erections, mood, energy and sleep, started before the first dose, gives the follow-up visit something concrete to compare. [41], [82]

What do people starting TRT report?

Public forums are full of men in their first days and weeks of TRT, asking whether what they feel is normal. The threads below are recent public Reddit discussions, read with their replies; they show what people experience, not how often it happens.

What do the first days feel like?

Anything from nothing to a lot. One man on 140 mg a week felt hyper-alert and skipped his usual coffee the day after his first dose; replies split between similar experiences and expectation. Another, two days into about 12 mg a day, felt nothing and was told day 2 was far too early to judge. [83], [84]

Some early changes were unpleasant. After a first 100 mg dose, one man felt calm for two days, then warm, sweaty, restless and unable to sleep. Another felt better than he had in years for several days, then had severe anxiety, racing thoughts and raised blood pressure after a later dose. [85], [86]

What happens by week 4 and month 3?

The range is wide. One man who started at 100 mg a week, half what his clinic suggested, felt better from week 1 and had back acne by week 12. Others felt little: no change at week 4 on 100 mg every 2 weeks, no clear benefit by week 8 on a cautious 60 mg a week despite much higher levels, and "unimpressed" at week 12 on 100 mg a week, with fewer morning erections, mood swings and ankle swelling. [87], [88], [89], [90]

Early gains sometimes faded. One man had much better erections for 5–6 weeks on 200 mg a week, then weaker ones by week 9, with very high testosterone and estradiol results and a hematocrit of 54.2%. [91]

What goes wrong with the first doses?

Volume and schedule mistakes come up again and again. One man injected a whole 1 mL vial (200 mg) for his first dose, thinking one vial was one dose, when his prescription was 0.25 mL every 2 weeks. Another's label said both 0.3 mL and 100 mg, which do not match at 200 mg/mL. A third, injecting 1 mL into his thigh each week, had soreness for days until he halved the volume. [92], [93], [94]

Why do first blood results surprise people?

Because timing, dose and other medicines all move the number, and the number does not always match how people feel. A man on gel felt more alert within hours, yet his testosterone had barely changed after a month. A man taking hCG alongside 80 mg a week measured about 1,300 ng/dL at a month, and about 1,800 ng/dL after lowering to 60 mg, with a hematocrit of 52%. Another's trough after 4 months on 80 mg a week was below his pretreatment level. [95], [96], [97], [98]

Schedules matter too. One man felt well on 100 mg weekly; when the same dose was moved to every 14 days, his day-13 level was 92 ng/dL and he felt much worse. At 4 weeks, another was offered a higher dose plus anastrozole although he felt no different; replies disagreed, and guidelines do not recommend routine aromatase inhibitors. [99], [100]

Who regrets starting, and why?

Regret shows up both on day 1 and months in. One man with untreated moderate sleep apnea regretted his first injection the next day. Another, who had few symptoms before starting, reported new anxiety and sexual problems after about 7 weekly injections while also losing weight on a GLP-1 medicine. A man in his 20s who started with a baseline of 550 ng/dL reported little benefit, heavy hair shedding and breast tissue growth after 6 months, and planned to stop because he wanted children. [101], [102], [103]

How can you judge an early TRT story?

Ask: Was low testosterone confirmed on two morning tests, and was the cause looked for? What form, dose and schedule, and how long after a dose was blood drawn? What else started at the same time: hCG, an aromatase inhibitor, a GLP-1 medicine, a new training plan, CPAP? And what did the follow-up visit show? One man about to start worried that success stories had inflated his expectations; replies ranged from life-changing to "feels normal". [104]

These selected discussions show what people experience and the questions research has not answered. They are not a survey of all men on TRT, a success rate or a substitute for the studies above.

What should you track in the first months?

Testosterone at the right point in the dosing cycle, hematocrit, PSA where your guideline or age calls for it, blood pressure, and the symptoms that led to treatment. Use this summary to prepare questions for your prescriber; it is not a personal testing plan. [3], [2]

[2], [5], [3], [28], [24], [31], [12]

In 24-hour blood-pressure studies, average systolic pressure rose 3.9 mm Hg after 12 weeks on Xyosted, 4.9 after 4 months on Jatenzo, 4.3 on Tlando, 1.7 on Kyzatrex, 3.1 after 16 weeks on Aveed and 1.9 after 16 weeks on 1.62% gel. [5], [31], [28], [24], [32], [105], [12]

Write down the date and time of every blood draw and when your last dose was. Without that, a result cannot be compared with the next one. The testosterone level visualizer shows how injection frequency changes the peaks and troughs, and the TRT blood work guide covers each test.

Common questions about starting TRT

How long does TRT take to work?

Weeks for sex drive, months for most other changes. In studies, sex drive rose from about 3 weeks, depressive symptoms eased by about 6 weeks, erections kept improving for 9 weeks or longer and body composition changed over 12–16 weeks. Energy is the least predictable. Most guidelines judge the response between 3 and 12 months. [7], [8], [3] See what changed, and when.

When is the first blood test after starting TRT?

It depends on the form and the guideline. The AUA checks gels at 2–4 weeks and cypionate or enanthate after 3–4 injections; the Xyosted label checks at 6 weeks; the Endocrine Society and the VA recheck at 3–6 months, and the EAU and CUA at 3 months. The draw time within the dosing cycle matters as much as the week. [2], [5], [3], [4], [14] See the key numbers.

Will I lose fertility right away?

No, but it starts falling with the first doses, and TRT is not reliable birth control. In a WHO contraception trial at 200 mg a week, 65% of healthy men had no sperm by 6 months, and those who got there took an average of 120 days. After hormonal contraception studies in healthy men, 90% recovered to a normal count (20 million per mL) within a year of stopping; recovery after longer TRT may be slower. If you may want children, discuss sperm banking or alternatives before starting. [13], [106], [3] See the TRT and fertility guide.

Do I have to stay on TRT forever?

Not necessarily. Most guidelines treat the first 3–12 months as a trial and advise stopping if symptoms have not improved despite normal levels; the UK Society for Endocrinology instead expects lifelong treatment for a confirmed diagnosis. After stopping, your own production takes time to recover. [2], [17] See the stopping rules and the stopping TRT guide.

Does TRT cause heart attacks?

The largest trial found no rise, within its safety margin. In TRAVERSE, heart attack, stroke or death from heart disease occurred in 7.0% of men on testosterone gel and 7.3% on placebo (hazard ratio 0.96, 95% confidence interval 0.78 to 1.17). Atrial fibrillation (3.5% vs 2.4%), acute kidney injury (2.3% vs 1.5%) and pulmonary embolism (0.9% vs 0.5%) were more common. The trial tested only gel, in men at high heart risk, for an average of 21.7 months of treatment, and about 61% stopped their study gel early. [57], [55] See what TRAVERSE showed.

Is TRT the same as taking steroids?

Testosterone is legally an anabolic steroid, but replacement aims to bring a low level back into the normal range under monitoring. Performance use usually means far higher doses, often of several drugs combined, which an Endocrine Society statement links with heart, mental-health and hormonal harms. [18], [107] See TRT vs steroids.

Will TRT fix erectile dysfunction?

Sometimes partly, often not fully. Testosterone raised desire more than erections in placebo-controlled trials: erectile scores rose about 2 points in pooled data, TRAVERSE found no improvement in erections, and in T4DM only 3 more men in 100 than on placebo had a meaningful gain. [43], [44], [51] See the TRT and sexual health guide.

Can supplements replace TRT?

Not for confirmed hypogonadism. In a review of 50 "testosterone booster" products, only 27 of their 109 ingredients had any data showing a testosterone rise. Weight loss does raise testosterone in men with obesity: by about 2.9 nmol/L on a low-calorie diet and 8.7 nmol/L after bariatric surgery in a meta-analysis. [108], [109] See raising testosterone naturally.

Glossary

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

Aromatase inhibitor

A medicine, such as anastrozole, that blocks the enzyme that turns testosterone into estradiol. The VA does not generally recommend them for men on testosterone.

Azoospermia

No sperm at all in a semen sample.

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.

Depot

A pool of medicine left in the body, such as oil in a muscle, that releases the drug slowly over days or weeks.

Ester

A chemical tail joined to testosterone that makes it dissolve in oil and release slowly after injection. The body removes the tail to free testosterone. Cypionate, enanthate and undecanoate are esters.

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.

Clinical guideline

Recommendations written by a medical society or health system, based on its review of the evidence and expert judgment. Different guidelines can reach different conclusions.

Half-life

The time it takes for the level of a substance in the blood to fall by half. For injected testosterone cypionate the label gives about 8 days, which reflects slow release from the oil rather than testosterone itself.

Hematocrit

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

Secondary hypogonadism (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.

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.

IIEF (International Index of Erectile Function)

A standard questionnaire that scores erectile and sexual function. A gain of about 2 points on its erectile section is enough to matter for mild erectile dysfunction.

Intramuscular (IM)

Injected into a muscle. US testosterone cypionate labels specify deep injection into the buttock muscle.

LH (luteinizing hormone)

A pituitary hormone that tells the testicles to make testosterone. Testosterone therapy switches it off.

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.

Mid-interval level

A blood test taken halfway between two injections, such as day 3–4 of a weekly schedule. Several guidelines use it to judge the dose.

Open study (open-label)

A study in which everyone knows they are getting the treatment and there is no placebo group. It shows what happened, but not how much was caused by the medicine rather than expectation.

Placebo

A dummy treatment with no active ingredient, used as a comparison in studies.

Pulmonary oil microembolism (POME)

Tiny droplets of injected oil reaching the lungs, causing a sudden cough or shortness of breath soon after an injection. The Aveed label carries a boxed warning for 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.

Schedule III

A US category of controlled substances with accepted medical use and some risk of misuse. Testosterone is listed there, which limits refills to 5 within 6 months.

SERM (selective estrogen receptor modulator)

A tablet, such as clomiphene, enclomiphene or tamoxifen, that blocks estrogen's feedback in the brain so the pituitary releases more LH and FSH.

Obstructive sleep apnea

Repeated blocking of the airway during sleep, causing pauses in breathing and drops in oxygen. Loud snoring and daytime sleepiness are common signs.

Steady state

The point where each dose replaces what the body clears, so the blood level stops climbing from one dose to the next. Gels reach it in days; weekly injections take several weeks.

Subcutaneous (SC)

Injected into the fatty layer just under the skin. Xyosted is given this way, and some prescribers use this route for other testosterone injections.

Syringe units

Markings on an insulin syringe that measure volume. On a U-100 syringe, 100 units equal 1 mL, so 0.5 mL is 50 units.

Thrombophilia

An inherited or acquired tendency to form blood clots more easily than normal.

Titration

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

Trough level

The lowest level of a drug in the blood, measured just before the next dose. Some UK guidelines judge injections by it.

TRT (testosterone replacement therapy)

Prescribed testosterone, by injection, gel or other forms, for men with low testosterone. It switches off the brain's LH and FSH signals.

WADA

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

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: clinical guidelines and statements from nine medical bodies, current product labels from the US and UK, published clinical trials and studies, insurance and clinic records, and regulatory documents. We also reviewed public online forums where men describe their first weeks and months on TRT.

The guide cites 109 sources, including 41 studies in people, 10 clinical guidelines and society statements, 14 product labels and 22 public community discussions. Each type of source answers a different question. Guidelines and labels show what clinicians are told to do. Trials and studies show what was measured. 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