Testosterone gel is plain testosterone dissolved in a fast-drying alcohol gel that is rubbed onto the skin once a day. Testogel is the brand sold in the UK by Besins Healthcare. The same company holds the US approvals for AndroGel 1% and AndroGel 1.62%, the gels used in most of the large modern testosterone trials.
The gel is approved only as testosterone replacement for men with confirmed hypogonadism (low testosterone caused by disease of the testes, pituitary or hypothalamus). Its defining feature is steady daily delivery without injection peaks. Its defining risk is transfer: the US label carries a boxed warning because children have been virilized after touching a parent’s application site.
This page summarizes what the US and UK labels and the main clinical trials report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Androgen; testosterone itself, with no ester attached |
| Brands | Testogel (UK, Besins Healthcare); AndroGel 1% (US, approved 2000) and AndroGel 1.62% (US, approved 2011) |
| Route | Transdermal gel, applied once daily, usually in the morning |
| Labeled daily doses | 1% gel: 50–100 mg; 1.62% gel: 20.25–81 mg (testosterone content, not gel weight) |
| Share absorbed | About 10% of the applied dose (AndroGel 1% label); 9–14% (Testogel 50 mg SmPC) |
| Half-life | Circulating testosterone 10–100 minutes (label); the skin acts as a 24-hour reservoir |
| After stopping | Back to baseline within 48–72 h (1.62% gel) to about 5 days (1% gel) |
| US boxed warning | Secondary exposure: virilization of children |
| US schedule | Controlled substance, Schedule III |
| WADA | Prohibited at all times (S1.1, anabolic androgenic steroids) |
What it is
The active ingredient is testosterone (17β-hydroxyandrost-4-en-3-one), the same molecule the testes make (AndroGel 1% label). Unlike injectable testosterone cypionate or testosterone enanthate, there is no ester. Every labeled milligram is testosterone, and the release rate is set by the skin rather than by an oil depot.
The gel itself is a hydroalcoholic (alcohol and water) base. The US and UK products list the same five inactive ingredients: carbomer 980, isopropyl myristate, ethanol, sodium hydroxide and purified water (Testogel 50 mg SmPC; AndroGel 1.62% label). The alcohol evaporates within minutes and leaves testosterone in the outer skin layers.
Two concentrations exist, and they are not interchangeable milligram for milligram:
| Product | Concentration | Unit dose | Starting dose | Labeled range |
|---|---|---|---|---|
| AndroGel 1% (US) | 10 mg/g | 12.5 mg per pump press; 25 or 50 mg packets | 50 mg/day | 50–100 mg/day |
| Testogel 50 mg sachet (UK) | 10 mg/g | 50 mg in 5 g of gel | 50 mg/day | Up to 100 mg/day, in 2.5 g steps |
| AndroGel 1.62% (US) | 16.2 mg/g | 20.25 mg per pump press; 20.25 or 40.5 mg packets | 40.5 mg/day | 20.25–81 mg/day |
| Testogel 16.2 mg/g pump and 40.5 mg sachet (UK) | 16.2 mg/g | 20.25 mg per pump press; 40.5 mg in 2.5 g | 40.5 mg/day | Up to 81 mg/day |
Sources: AndroGel 1% label; AndroGel 1.62% label; Testogel 50 mg SmPC; Testogel 16.2 mg/g SmPC; Testogel 40.5 mg SmPC.
Both US labels state that the dose and application site “are not substitutable with other topical testosterone products.” Related topical pages in this library cover testosterone cream and DHT gel. Long-acting options are covered under testosterone undecanoate.
Pharmacokinetics
The skin works as a reservoir. Testosterone moves from it into the blood over the whole 24 hours after each application (AndroGel 1% label). Key points from the labels:
- Onset. With 100 mg of the 1% gel, serum testosterone rose in all patients within 30 minutes, and 8 of 9 were in the normal range by 4 hours.
- Steady state. Levels approach steady state after the first day and are stable by day 2–3.
- Absorption. About 10% of the applied dose reaches the blood (AndroGel 1%). The Testogel SmPCs give 9–14% for the 50 mg sachet and 1–8.5% for the 16.2 mg/g gel.
- Washout. After the last dose, levels stay normal for 24–48 hours and return to pretreatment values by the fifth day (1% gel). For the 1.62% gel the label gives 48–72 hours, and the Testogel SmPCs give 72–96 hours.
The testosterone molecule itself is short-lived. The label notes that published half-lives of circulating testosterone range from 10 to 100 minutes. The once-daily schedule works because of the skin depot, not because testosterone lingers in the blood.
Blood levels by dose
In the pivotal 180-day AndroGel 1% trial, mean serum testosterone on day 180 was as follows (label Table 5):
| Daily dose | n | Average (Cavg) | Peak (Cmax) | Trough (Cmin) |
|---|---|---|---|---|
| 50 mg | 44 | 555 ng/dL | 830 ng/dL | 371 ng/dL |
| 75 mg | 37 | 601 ng/dL | 901 ng/dL | 406 ng/dL |
| 100 mg | 48 | 713 ng/dL | 1,083 ng/dL | 485 ng/dL |
Of 129 titrated men with enough data, 87% had an average level in the normal range on day 180. In the 274-man placebo-controlled trial of the 1.62% gel, 81.6% reached an average level of 300–1,000 ng/dL at day 112. Peaks above 1,500 ng/dL occurred in 11.2% (AndroGel 1.62% label).
DHT and estradiol
Gels raise dihydrotestosterone (DHT), the more potent androgen made from testosterone by the enzyme 5α-reductase, more than patches do. In the 227-man pharmacokinetic study, average DHT rose 3.6-fold with 50 mg/day gel and 4.6-fold with 100 mg/day, compared with 1.3-fold on a testosterone patch (Swerdloff et al., JCEM 2000). The DHT-to-testosterone ratio rose slightly but stayed in the normal range. The label gives steady-state ratios of 0.23–0.29 at 50 mg and 0.27–0.33 at 100 mg.
Estradiol rose within 30 days and stayed raised, but within the normal male range. SHBG (sex hormone-binding globulin) fell by 1–11%.
Washing, showering and skin products
The 1.62% label reports several practical studies:
| Situation | Effect on testosterone exposure |
|---|---|
| Shower 2 h after application | Average level 13% lower that day |
| Shower 6 h after application | 12% lower |
| Shower 10 h after application | No effect |
| Moisturizing lotion 1 h after application | Average level 14% higher |
| Sunscreen (SPF 50) 1 h after application | Average level 8% higher |
| Washing hands with soap right after applying | 96% less testosterone left on the hands |
The labeled wait before showering or swimming differs by product: 5 hours for AndroGel 1%, 2 hours for AndroGel 1.62%, and at least 1 hour for Testogel.
Approved medical use
The US labels cover replacement therapy in adult males with either of the following, congenital or acquired:
- primary hypogonadism (testicular failure, for example from Klinefelter syndrome, orchiectomy or chemotherapy);
- hypogonadotropic hypogonadism (pituitary or hypothalamic failure).
The diagnosis should be confirmed by morning testosterone below the normal range on at least two separate days. Safety and efficacy have not been established for “age-related hypogonadism,” in males under 18, or in women. The UK SmPCs approve Testogel for male hypogonadism confirmed by clinical features and biochemical tests.
Dose is adjusted to blood levels. For AndroGel 1.62%, the label uses a pre-dose morning level at about 14 and 28 days:
| Pre-dose morning testosterone | Action |
|---|---|
| Over 750 ng/dL | Lower the daily dose by 20.25 mg |
| 350–750 ng/dL | No change |
| Under 350 ng/dL | Raise the daily dose by 20.25 mg |
For AndroGel 1%, treatment should stop if levels consistently exceed the normal range at 50 mg/day. The Testogel 50 mg SmPC advises a morning level before application from day 3 onward, with a maximum of 10 g of gel (100 mg) per day.
What the research shows
Pivotal trial: sexual function, body composition and strength
The registration trial randomized 227 hypogonadal men to AndroGel 1% at 50 or 100 mg/day, or to a testosterone patch, for 180 days (Wang et al., JCEM 2000):
| Measure (at day 90) | Gel 50 mg/day | Gel 100 mg/day | Patch 5 mg/day |
|---|---|---|---|
| Lean body mass | +1.28 kg | +2.74 kg | +1.20 kg |
| Fat mass | −0.90 kg | −1.05 kg | No significant change |
| Leg press 1RM | +11 to 13 kg in all groups | +11 to 13 kg in all groups | +11 to 13 kg in all groups |
| Skin irritation (whole trial) | 5.5% across gel groups | 5.5% across gel groups | 66% |
Sexual function and mood improved by day 30 and did not improve further. Gains in lean mass and losses of fat tracked the average testosterone level reached. Strength gains did not grow between day 90 and day 180.
In an open-label extension, 163 men used the gel for up to 42 months (Wang et al., JCEM 2004). Lean mass gains, fat loss and improvements in sexual function and mood were maintained. Bone mineral density rose gradually, more in the spine than the hip. The extension had no placebo group, and muscle strength did not increase significantly.
Older men: the Testosterone Trials
The Testosterone Trials randomized 790 men aged 65 or older with testosterone under 275 ng/dL and symptoms to AndroGel 1% (starting at 5 g gel daily) or placebo gel for 1 year (Snyder et al., NEJM 2016). Testosterone rose to the mid-normal range for young men. Results:
- Sexual function: sexual activity, desire and erectile function improved significantly.
- Walking: in the Physical Function Trial alone, the share of men gaining at least 50 m in a 6-minute walk did not differ. Across all participants it did: 20.5% vs 12.6%.
- Vitality: no benefit on fatigue scores.
- Mood: slightly better mood and fewer depressive symptoms.
The authors noted the trial was too small to judge risks.
Cardiovascular safety: TRAVERSE
TRAVERSE randomized 5,246 men aged 45–80 with hypogonadism and existing or high cardiovascular risk to 1.62% testosterone gel or placebo gel (Lincoff et al., NEJM 2023). Doses were adjusted to keep testosterone at 350–750 ng/dL. Mean treatment lasted 21.7 months and mean follow-up 33.0 months. According to the label, the mean daily dose was 65 mg, mean testosterone rose from 220 ng/dL at baseline to about 420–440 ng/dL at 12–24 months, and about 61% of participants stopped their assigned gel or placebo during the study.
| Outcome | Testosterone gel | Placebo gel |
|---|---|---|
| Major adverse cardiac events (primary) | 7.0% | 7.3% |
| Nonfatal arrhythmia needing intervention | 5.2% | 3.3% |
| Atrial fibrillation | 3.5% | 2.4% |
| Acute kidney injury | 2.3% | 1.5% |
| Venous thromboembolism | 1.7% | 1.2% |
| Pulmonary embolism | 0.9% | 0.5% |
| Clinical fracture | 3.5% | 2.5% |
Primary outcome and named secondary findings from Lincoff et al. 2023; arrhythmia, VTE and fracture rates from the AndroGel 1.62% label and the AndroGel 1% label.
The primary result had a hazard ratio of 0.96 (95% CI 0.78–1.17), meeting the noninferiority goal. A fracture substudy of 5,204 men found more clinical fractures on testosterone, not fewer: hazard ratio 1.43 (95% CI 1.04–1.97) over a median 3.19 years (Snyder et al., NEJM 2024). TRAVERSE tested a gel kept in the physiologic range in older, high-risk men. It does not speak to supraphysiologic dosing.
Side effects and risks
Boxed warning: secondary exposure
The US labels report postmarketing cases of virilization in children exposed to a parent’s testosterone gel. Reported signs included enlargement of the penis or clitoris, pubic hair, increased erections and libido, aggressive behavior and advanced bone age. Most cases regressed once exposure stopped, but in a few, genital size did not fully return to normal and bone age stayed modestly advanced (AndroGel 1% label).
Transfer studies show how much clothing matters:
| Study | Unprotected skin contact | Application site covered by a shirt |
|---|---|---|
| AndroGel 1%, 100 mg, 38 couples, daily 15-minute contact | All female partners exceeded 2× their baseline testosterone | Transfer completely prevented |
| AndroGel 1.62%, 81 mg, single 15-minute contact | Female partners’ average testosterone up 280% | Up 6% |
The labels advise washing hands right after applying, covering the site with clothing once dry, and washing the site before expected skin-to-skin contact. Pregnant women must avoid contact because testosterone can virilize a female fetus.
Common adverse reactions
In the 180-day AndroGel 1% trial, these treatment-related events were reported (label Table 2):
| Event | 50 mg (n = 77) | 75 mg (n = 40) | 100 mg (n = 78) |
|---|---|---|---|
| Acne | 1% | 3% | 8% |
| Application site reaction | 5% | 3% | 4% |
| Abnormal lab test | 6% | 5% | 3% |
| Prostate disorder | 3% | 3% | 5% |
| Headache | 4% | 3% | 0% |
| Hypertension | 3% | 0% | 3% |
| Gynecomastia | 1% | 0% | 3% |
Six patients (4%) stopped because of adverse events; none stopped because of skin reactions. The Testogel SmPC lists skin reactions at the site (redness, acne, dry skin) and emotional symptoms as the most frequent effects.
Hematocrit
Testosterone raises hematocrit (the share of blood made up of red cells). Gels raise it, but less than short-acting injections. A network meta-analysis of 29 randomized trials (3,393 men) estimated a mean rise versus placebo of 3.0% (95% CI 1.8–4.3) for gels and 4.0% (95% CI 2.9–5.1) for intramuscular enanthate or cypionate (Nackeeran et al., J Urol 2022). In a clinical cohort, hematocrit above 50% occurred in 12.8% of gel users versus 66.7% of injection users, though the injection group was younger and started higher (Pastuszak et al., Sex Med 2015).
The labels advise checking hematocrit before starting, at 3–6 months, and then yearly, and stopping until it falls if it becomes elevated.
Prostate and PSA
In the pivotal trial, mean PSA rose by 0.26 ng/mL over 6 months. In the 3-year extension, 18% of men met the protocol definition of a PSA increase (doubling, or any value over 6 ng/mL), and prostate cancer was found on biopsy in two of them. The gel is contraindicated in men with known or suspected prostate cancer or with breast cancer, and men with benign prostatic hyperplasia may see their symptoms worsen.
Blood pressure
In a 16-week ambulatory monitoring study of the 1.62% gel, 24-hour blood pressure rose by 1.9/1.3 mm Hg on average. In men already on blood pressure drugs it rose by 3.0/2.2 mm Hg. In TRAVERSE, systolic pressure differed from placebo by 1.5 mm Hg at 36 months. The label does not recommend the gel in uncontrolled hypertension (AndroGel 1.62% label).
Fertility and hormonal suppression
Like all external testosterone, the gel suppresses LH and FSH, the pituitary hormones that drive the testes. In the pharmacokinetic study, LH and FSH fell in proportion to serum testosterone (Swerdloff et al., JCEM 2000). The UK SmPC describes suppression of sperm production as reversible. The US label is more cautious, stating that the effect on fertility “may be irreversible.”
Other warnings and interactions
The labels also list:
- venous thromboembolism (deep vein thrombosis and pulmonary embolism);
- edema, with or without heart failure, in men with heart, kidney or liver disease;
- sleep apnea, especially with obesity or chronic lung disease;
- gynecomastia;
- flammability until the gel has dried.
Interactions include changes in anticoagulant effect (closer INR monitoring), lower insulin needs in diabetes, and more fluid retention with corticosteroids. Unlike oral 17α-alkylated androgens such as methyltestosterone, the gel “is not known to cause” peliosis hepatis or liver tumors, according to the label.
Monitoring
These checkpoints come from the product labels:
| What | When |
|---|---|
| Serum testosterone | AndroGel 1.62%: pre-dose morning level at about 14 and 28 days, then periodically. Testogel 50 mg: morning, before application, from day 3 onward |
| Hematocrit | Before starting, at 3–6 months, then yearly |
| PSA and prostate exam | Testogel SmPC: at least yearly, twice yearly in older or higher-risk men |
| Blood pressure | Periodically, especially in men with hypertension |
| Lipids and liver tests | Periodically |
Legal status and use outside medicine
In the US, testosterone gel is a Schedule III controlled substance (21 CFR 1308.13). In the UK, Testogel is a licensed medicine held by Besins Healthcare (UK) Ltd (50 mg sachet: PL 42714/0002).
Testosterone is prohibited at all times, in and out of competition, under section S1.1 of the WADA 2026 Prohibited List. The Testogel SmPC warns athletes that it may cause a positive doping test. The US label notes that testosterone is abused, usually at doses above those prescribed and with other anabolic steroids, and that this abuse has been linked to serious cardiovascular and psychiatric effects.
Key takeaways
- Plain testosterone, delivered through the skin. There is no ester. The skin acts as a 24-hour depot, so levels are steady by day 2–3 and fall back to baseline within a few days of stopping.
- Only a fraction is absorbed. About 10% of the 1% gel reaches the blood, and strengths are not interchangeable between products.
- Transfer is the signature risk. Children have been virilized by contact with a parent’s application site. A shirt over the dried gel blocked transfer in the label studies.
- Modest, physiologic effects. In the pivotal trial, 100 mg/day added about 2.7 kg of lean mass at 90 days. In older men, sexual function improved, but vitality did not.
- Large safety trial, mixed signals. TRAVERSE found no increase in major cardiac events, but more atrial fibrillation, pulmonary embolism, kidney injury and fractures than placebo.
- Hematocrit rises less than with injections. It still needs checking, along with PSA and blood pressure.
Sources
- Besins Healthcare / ASCEND Therapeutics. AndroGel (testosterone gel) 1%, prescribing information, revised July 2025. DailyMed; Drugs@FDA, NDA 021015.
- Besins Healthcare / ASCEND Therapeutics. AndroGel (testosterone gel) 1.62%, prescribing information. DailyMed; Drugs@FDA, NDA 022309.
- Besins Healthcare (UK) Ltd. Testogel 50 mg, transdermal gel in sachet: summary of product characteristics (PL 42714/0002), revised January 2025. EMC.
- Besins Healthcare. Testogel 16.2 mg/g gel: summary of product characteristics, revised January 2025. EMC.
- Besins Healthcare (UK) Ltd. Testogel 40.5 mg, transdermal gel in sachet: summary of product characteristics (PL 42714/0005), revised January 2025. EMC.
- Swerdloff RS, Wang C, Cunningham G, et al. Long-term pharmacokinetics of transdermal testosterone gel in hypogonadal men. J Clin Endocrinol Metab. 2000;85(12):4500–4510. PubMed.
- Wang C, Swerdloff RS, Iranmanesh A, et al. Transdermal testosterone gel improves sexual function, mood, muscle strength, and body composition parameters in hypogonadal men. J Clin Endocrinol Metab. 2000;85(8):2839–2853. PubMed.
- Wang C, Cunningham G, Dobs A, et al. Long-term testosterone gel (AndroGel) treatment maintains beneficial effects on sexual function and mood, lean and fat mass, and bone mineral density in hypogonadal men. J Clin Endocrinol Metab. 2004;89(5):2085–2098. PubMed.
- Snyder PJ, Bhasin S, Cunningham GR, et al. Effects of testosterone treatment in older men. N Engl J Med. 2016;374(7):611–624. PubMed.
- Lincoff AM, Bhasin S, Flevaris P, et al. Cardiovascular safety of testosterone-replacement therapy. N Engl J Med. 2023;389(2):107–117. PubMed.
- Snyder PJ, Bauer DC, Ellenberg SS, et al. Testosterone treatment and fractures in men with hypogonadism. N Engl J Med. 2024;390(3):203–211. PubMed.
- Nackeeran S, Kohn T, Gonzalez D, et al. The effect of route of testosterone on changes in hematocrit: a systematic review and Bayesian network meta-analysis of randomized trials. J Urol. 2022;207(1):44–51. PubMed.
- Pastuszak AW, Gomez LP, Scovell JM, et al. Comparison of the effects of testosterone gels, injections, and pellets on serum hormones, erythrocytosis, lipids, and prostate-specific antigen. Sex Med. 2015;3(3):165–173. PubMed.
- US Drug Enforcement Administration. Schedules of controlled substances: Schedule III, 21 CFR 1308.13. eCFR.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA 2026 Prohibited List.