Does Testogel make your penis larger? This is a common question among men considering testosterone replacement therapy. Testogel is a prescription treatment licensed in the UK for male hypogonadism—a condition where the body produces insufficient testosterone. Whilst Testogel can improve sexual function, energy levels, and quality of life in men with confirmed testosterone deficiency, there is no credible scientific evidence that it increases penis size in adults. Penile growth occurs during foetal development and puberty; once these developmental phases are complete, the penis does not respond to testosterone with further growth. This article explains what Testogel does, how testosterone affects male development, and when treatment may be appropriate.

What Is Testogel and How Does It Work?

Testogel is a prescription testosterone replacement therapy (TRT) available in the UK, licensed by the Medicines and Healthcare products Regulatory Agency (MHRA). It contains testosterone as the active ingredient and is formulated as a clear, colourless gel applied directly to the skin. Testogel 1% sachets can be applied to the shoulders, upper arms, or abdomen, while Testogel 16.2 mg/g pump should only be applied to the shoulders or upper arms. Once applied, the testosterone is absorbed through the skin into the bloodstream, where it supplements the body's natural hormone levels.

The primary indication for Testogel is the treatment of male hypogonadism—a clinical condition characterised by abnormally low testosterone levels confirmed through blood tests. Symptoms of hypogonadism may include reduced libido, erectile dysfunction, fatigue, loss of muscle mass, mood disturbances, and decreased bone density. Testogel works by restoring testosterone to physiological levels, thereby alleviating these symptoms and improving quality of life.

Mechanism of action: Testosterone is an androgen hormone that binds to androgen receptors in various tissues throughout the body. It plays a crucial role in maintaining male secondary sexual characteristics, muscle and bone mass, red blood cell production, and sexual function. By delivering exogenous testosterone transdermally, Testogel bypasses first-pass hepatic metabolism, providing steady hormone levels throughout the day when applied as directed.

It is important to understand that Testogel is not licensed for cosmetic purposes or body enhancement. It should only be used under medical supervision following appropriate investigation and diagnosis of testosterone deficiency. Misuse of testosterone products carries significant health risks, including fluid retention, increased haematocrit, potential blood pressure elevation, acne, and possible venous thromboembolism.

Important safety information: Testogel should never be applied to the genital area. Apply to clean, dry, intact skin, wash hands thoroughly immediately after application, and allow the gel to dry completely before dressing. Cover the application site with clothing once dry, and avoid washing the area or swimming/showering for at least 2-6 hours (depending on the specific product). The gel contains alcohol and is flammable, so avoid fire, flames or smoking until the gel has dried.

Testosterone and Penis Development: What the Evidence Shows

A common question among men considering testosterone therapy concerns whether it can increase penis size. To address this, it is essential to understand the biological timeline of penile development. The penis undergoes its primary growth during two critical periods: in utero (during foetal development) and during puberty. Both phases are heavily influenced by testosterone and its more potent metabolite, dihydrotestosterone (DHT).

During foetal development, androgens are responsible for the differentiation and growth of male external genitalia. During puberty, rising testosterone levels trigger further penile growth, typically between ages 10 and 16, alongside other secondary sexual characteristics such as voice deepening, facial hair growth, and increased muscle mass. By the end of puberty, penile growth is generally complete.

In adult men, there is no credible scientific evidence that testosterone replacement therapy, including Testogel, increases penis size. Once puberty is complete, the growth potential of penile tissue is exhausted, and the penis does not respond to testosterone with further growth as it did during developmental periods.

Some men with severe, untreated hypogonadism from childhood (prepubertal onset) may experience incomplete genital development. In such rare cases, early testosterone replacement during adolescence may support normal pubertal development. However, this is distinct from adult-onset hypogonadism, where genital development has already been completed. For adult men with normal pubertal development, Testogel will not alter penis dimensions. This is an important distinction that should inform realistic expectations about testosterone therapy.

Realistic Effects of Testogel on Male Sexual Health

While Testogel does not increase penis size, it can have meaningful benefits for sexual health in men with confirmed testosterone deficiency. Understanding these realistic effects helps set appropriate expectations and supports informed decision-making.

Improvements in sexual function that may occur with Testogel treatment include:

• Enhanced libido: Many men with hypogonadism report reduced sexual desire. Restoring testosterone to normal physiological levels often improves sex drive, though response varies individually.

• Better erectile function: Testosterone plays a role in the mechanisms underlying erections, including nitric oxide production in penile tissue. Men with low testosterone and erectile dysfunction may experience improvement, though it's important to note that phosphodiesterase-5 (PDE5) inhibitors remain the first-line treatment for erectile dysfunction. Testosterone therapy may improve response to PDE5 inhibitors in hypogonadal men.

• Increased energy and mood: Fatigue and low mood associated with hypogonadism can indirectly affect sexual interest and performance. Addressing these symptoms may improve overall sexual wellbeing.

• Improved body composition: Testosterone therapy can increase lean muscle mass and reduce fat mass, which may enhance body confidence and self-esteem.

Important considerations: The benefits of Testogel are most pronounced in men with genuinely low testosterone levels. UK specialist guidelines (British Society for Sexual Medicine, Society for Endocrinology) typically recommend treatment for men with total testosterone below 8 nmol/L, with consideration in the 8-12 nmol/L range if symptoms are present and free testosterone is low. Diagnosis requires two morning blood samples. Men with normal testosterone levels will not experience additional benefits and may face unnecessary risks.

Common adverse effects of Testogel include skin reactions at the application site, acne, mood changes, increased haematocrit (red blood cell concentration), fluid retention, and potential blood pressure increases. Regular monitoring is essential, including testosterone levels, haematocrit (reduce or pause treatment if >0.54), PSA, and blood pressure at baseline, 3-6 months, then annually. Testogel can also transfer to others through skin contact, posing risks particularly to women and children, so careful application and handwashing are crucial.

It's important to note that testosterone therapy suppresses sperm production and should be avoided by men trying to conceive. Specialist referral for alternative treatments may be appropriate in these cases.

When to Speak to Your GP About Testosterone Treatment

If you are experiencing symptoms that may be related to low testosterone, it is important to seek medical advice rather than self-diagnosing or obtaining treatments without supervision. Appropriate reasons to consult your GP include:

• Persistent symptoms such as reduced libido, erectile difficulties, unexplained fatigue, low mood, or loss of muscle mass

• Changes in physical characteristics including decreased body hair, breast tissue development (gynaecomastia), or reduced testicular size

• Concerns about fertility, as testosterone levels affect sperm production

• Osteoporosis or fractures at a relatively young age, which may indicate long-standing testosterone deficiency

Your GP will take a comprehensive medical history and conduct a physical examination. If testosterone deficiency is suspected, they will arrange blood tests to measure total testosterone levels, ideally taken between 8am and 11am when levels are naturally highest. Repeat testing is usually required to confirm the diagnosis, as testosterone levels can fluctuate.

UK specialist guidelines recommend that testosterone replacement should only be initiated when there is both biochemical evidence of deficiency and associated clinical symptoms. Additional investigations may include luteinising hormone (LH), follicle-stimulating hormone (FSH), prolactin, sex hormone binding globulin (SHBG), and calculated free testosterone. Abnormal results may prompt referral to an endocrinologist, particularly if secondary hypogonadism is suspected or if prolactin is elevated. Urgent referral is needed if headaches or visual disturbances accompany hormonal abnormalities.

Contraindications and cautions: Testogel must not be used in men with known or suspected prostate or breast cancer, or hypersensitivity to any ingredients. Caution is needed in men with severe cardiac, hepatic or renal disease due to risk of fluid retention. Treatment should not be started if haematocrit is above 0.54 until the cause is investigated and addressed. Your GP will assess your individual risk factors, including cardiovascular health and prostate-specific antigen (PSA) levels, with urology referral if PSA is elevated or digital rectal examination abnormal.

Ongoing monitoring is essential once treatment begins. This typically includes regular blood tests to check testosterone levels, haematocrit, PSA, and blood pressure. If you experience any concerning symptoms while using Testogel—such as chest pain, shortness of breath, leg swelling, or urinary difficulties—contact your GP promptly. Testosterone therapy is a long-term commitment requiring medical supervision to ensure both safety and efficacy, and it should never be used for purposes other than treating confirmed hypogonadism.

If you experience side effects from Testogel, report them to your doctor and consider reporting them through the MHRA Yellow Card scheme (website or app), which helps monitor medication safety.

Frequently Asked Questions