Understanding how to take Testogel correctly is essential for safe and effective testosterone replacement therapy. Testogel is a transdermal gel licensed in the UK for treating male hypogonadism, a condition where the testes produce insufficient testosterone. Proper application technique, timing, and precautions are crucial to optimise absorption, maintain stable testosterone levels, and prevent accidental transfer to others—particularly women and children. This guide provides comprehensive, evidence-based instructions on using Testogel safely, recognising side effects, and understanding when this treatment is appropriate. Always follow your clinician's specific instructions and attend regular monitoring appointments.

What Is Testogel and How Does It Work?

Testogel is a transdermal testosterone replacement therapy (TRT) licensed in the UK for treating male hypogonadism—a condition where the testes produce insufficient testosterone. It contains testosterone as the active ingredient, formulated as a clear or slightly opalescent gel in sachets (Testogel 1%) or pump dispensers (Testogel 16.2 mg/g).

The gel works through percutaneous absorption: when applied to intact skin, testosterone is gradually absorbed into the bloodstream over several hours. This delivery method bypasses first-pass hepatic metabolism, providing more stable serum testosterone levels compared to oral preparations. Once absorbed, testosterone binds to androgen receptors throughout the body, influencing protein synthesis, bone density, muscle mass, libido, mood, and secondary sexual characteristics.

Mechanism of action: Testosterone exerts its effects by binding to intracellular androgen receptors in target tissues. The hormone-receptor complex then translocates to the cell nucleus, where it regulates gene transcription. This process supports normal male physiological functions including spermatogenesis, erythropoiesis, and maintenance of lean body mass. Importantly, exogenous testosterone can suppress natural sperm production, making it unsuitable for men seeking to preserve fertility.

Testogel is indicated specifically for testosterone deficiency confirmed by clinical symptoms (reduced libido, erectile dysfunction, fatigue, decreased muscle mass) and biochemical testing showing consistently low serum testosterone levels. The Medicines and Healthcare products Regulatory Agency (MHRA) emphasises that TRT should only be initiated following thorough endocrine assessment, as symptoms of hypogonadism can overlap with other conditions including depression, thyroid disorders, and sleep apnoea. Treatment aims to restore testosterone to physiological levels, thereby alleviating symptoms and improving bone density and lean body mass.

How to Apply Testogel Correctly

Correct application technique is essential for optimal testosterone absorption and to minimise the risk of transfer to others, particularly women and children. The MHRA has issued specific guidance on safe use following reports of virilisation in children exposed to testosterone gels.

Application sites:

• Testogel 1% sachets: Apply to clean, dry, intact skin on the shoulders, upper arms, or abdomen.

• Testogel 16.2 mg/g pump: Apply only to the shoulders and upper arms.

Never apply to the genital area, broken or irritated skin as this increases irritation risk and does not improve absorption. Rotate application sites daily to reduce local skin reactions.

Step-by-step application:

• Wash and dry your hands thoroughly before opening the sachet or using the pump.

• Squeeze the entire contents of the sachet (or the prescribed number of pump actuations) onto one palm.

• Apply the gel in a thin, even layer over the designated area. Do not rub vigorously—gentle spreading is sufficient.

• Allow the gel to dry completely for 3–5 minutes before dressing. Note that the gel is flammable until dry.

• The application site should be covered with clothing once dry.

• Wash your hands thoroughly with soap and water immediately after application to prevent accidental transfer.

Timing considerations: Apply Testogel at approximately the same time each day, preferably in the morning, to mimic natural circadian testosterone rhythms. Avoid swimming, bathing, or showering for at least:

• 6 hours after applying Testogel 1% sachets

• 2 hours after applying Testogel 16.2 mg/g pump

Preventing transfer: This is critical for safety. Cover the application site with clothing once dry. If direct skin-to-skin contact with others is anticipated (particularly with pregnant women or children), wash the application area thoroughly with soap and water beforehand. Partners and family members should be informed about transfer risks. If accidental exposure occurs, the affected person should wash the contact area immediately with soap and water.

Common Side Effects and When to Seek Help

Like all medications, Testogel can cause adverse effects, though not everyone experiences them. Understanding common reactions and recognising warning signs requiring medical attention is essential for safe treatment.

Common side effects (affecting up to 1 in 10 patients):

• Skin reactions at the application site: redness, itching, dry skin, acne, or contact dermatitis. These are usually mild and may improve with site rotation.

• Mood changes: increased aggression, irritability, mood swings, or emotional lability.

• Prostate effects: benign prostatic hyperplasia symptoms may worsen, including urinary frequency, hesitancy, or nocturia.

• Haematological changes: elevated haemoglobin and haematocrit (polycythaemia), which increases thrombotic risk.

• Headache, dizziness, or hot flushes.

• Changes in libido: paradoxically, some men report either increased or decreased sexual desire.

Less common but significant adverse effects include:

• Gynaecomastia (breast tissue enlargement)

• Testicular atrophy due to suppression of endogenous testosterone production

• Sleep apnoea (worsening of existing condition)

• Fluid retention and peripheral oedema

• Hepatic dysfunction (rare with transdermal preparations)

When to seek urgent medical help:

• Chest pain, shortness of breath, or leg swelling (possible thromboembolism)

• Prolonged, painful erection lasting >4 hours (priapism—a rare but serious urological emergency)

• Signs of liver problems: persistent nausea, yellowing of skin/eyes, dark urine, severe abdominal pain

• Severe allergic reaction: facial swelling, difficulty breathing, widespread rash

• Mood disturbances: severe depression, suicidal thoughts, or uncontrollable aggression

Routine monitoring is essential during TRT. UK clinical guidance recommends checking serum testosterone for dose adjustment, haematocrit (at baseline, 3-6 months, then annually), and prostate-specific antigen (PSA) with digital rectal examination for men over 40 or at risk. Patients should attend all scheduled blood tests and report any new symptoms promptly to their GP or endocrinologist.

If you experience any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed above. You can also report side effects directly via the Yellow Card Scheme at yellowcard.mhra.gov.uk.

When to Use Testogel and Dosage Guidelines

Indications: Testogel is indicated exclusively for confirmed male hypogonadism—either primary (testicular failure) or secondary (hypothalamic-pituitary dysfunction). Diagnosis requires both:

• Clinical symptoms: reduced libido, erectile dysfunction, fatigue, reduced muscle mass, mood disturbances, or decreased bone density.

• Biochemical confirmation: at least two fasting morning serum testosterone measurements below the reference range (typically <8–12 nmol/L, though thresholds vary between laboratories).

Testogel is not licensed for age-related testosterone decline in otherwise healthy men, bodybuilding, or performance enhancement. The European Medicines Agency (EMA) has emphasised that TRT should not be used to treat non-specific symptoms in men with normal testosterone levels.

Standard dosage:

• Testogel 1% sachets: The usual starting dose is 50 mg testosterone daily (one 5 g sachet). Dose adjustments are made in 25 mg increments (range 25-100 mg daily).

• Testogel 16.2 mg/g pump: The starting dose is 40.5 mg testosterone (2 pump actuations) once daily. Dose adjustments are made in 20.25 mg increments (range 20.25-81 mg daily).

Dosage is adjusted based on clinical response and serum testosterone levels measured 2–4 weeks after initiation or dose change.

Contraindications: Testogel must not be used in patients with:

• Prostate or male breast cancer (current or suspected)

• Hypersensitivity to testosterone or excipients

Use with caution in patients with:

• Cardiovascular disease or risk factors

• Polycythaemia (haematocrit >54%)

• Untreated sleep apnoea

• Severe hepatic, renal or cardiac impairment

• Epilepsy or migraine

Special populations: Use with caution in elderly patients (increased cardiovascular and prostate cancer risk). Regular monitoring is particularly important in these groups. Women and children must never use Testogel due to virilisation risks.

Fertility considerations: Testosterone replacement therapy suppresses spermatogenesis and should not be used by men actively seeking fertility. Men wishing to father children should discuss alternative treatments with their specialist.

Patients should be counselled that TRT is typically long-term treatment. Abrupt discontinuation may cause symptom recurrence. Any decision to stop treatment should be made in consultation with the prescribing clinician, with consideration of gradual dose reduction where appropriate.

Frequently Asked Questions