Testogel is a prescription testosterone replacement therapy used to treat men with clinically confirmed hypogonadism—abnormally low testosterone levels. The correct dose varies between individuals and depends on the formulation prescribed, baseline testosterone levels, and clinical response. In the UK, Testogel is available as 1% sachets or a 16.2 mg/g metered-dose pump, with starting doses typically ranging from 20.25 mg to 50 mg of testosterone applied once daily. Dosing must be determined and monitored by a healthcare professional through regular blood tests. This article explains recommended dosages, application techniques, dose adjustments, and essential safety considerations for men using Testogel under medical supervision.

What Is Testogel and How Does It Work?

Testogel is a transdermal testosterone replacement therapy (TRT) prescribed to men with clinically confirmed hypogonadism—a condition characterised by abnormally low testosterone levels. Available in the UK as a gel containing testosterone in two formulations (1% sachets and 16.2 mg/g pump), Testogel is applied directly to the skin. The active ingredient, testosterone, is absorbed through the skin into the bloodstream, where it exerts its physiological effects.

Testosterone is the primary male sex hormone responsible for maintaining libido, muscle mass, bone density, red blood cell production, and overall energy levels. In men with hypogonadism, insufficient testosterone production can lead to symptoms including fatigue, reduced sexual desire, erectile dysfunction, mood disturbances, and loss of muscle strength. Testogel works by supplementing the body's natural testosterone, thereby alleviating these symptoms and restoring hormonal balance.

The gel formulation allows for steady daily absorption, providing relatively stable testosterone levels. Once applied, the alcohol-based carrier evaporates quickly, leaving testosterone on the skin surface for gradual absorption. Peak serum testosterone concentrations are typically reached within a few hours after application.

It is essential to understand that Testogel is a prescription-only medicine (POM) regulated by the MHRA. Diagnosis of hypogonadism must be confirmed through blood tests showing consistently low testosterone levels, typically measured on at least two separate occasions in the morning when testosterone levels are naturally highest. Testogel should only be used under medical supervision, as inappropriate use can lead to serious adverse effects.

Important contraindications and warnings: Testogel must not be used in men with known or suspected prostate cancer or breast cancer. It is not indicated for use in women or children. Caution is required in men with severe cardiac, hepatic, or renal insufficiency, and in those with thrombophilia or pre-existing polycythaemia. Exogenous testosterone can suppress spermatogenesis and may impair fertility; men wishing to father children should discuss this with their clinician before starting treatment.

Recommended Testogel Dosage for Men

Testogel is available in the UK in two formulations, each with specific dosing instructions:

Testogel 1% (50 mg/5 g sachets): The standard starting dose is 5 g of gel (50 mg testosterone) applied once daily. Based on clinical response and serum testosterone levels, the dose may be adjusted:

• Maintenance dose: 5 g daily (50 mg)

• If needed, increase to 7.5 g daily (75 mg) or 10 g daily (100 mg)

• Maximum dose: 10 g daily (100 mg)

Testogel 16.2 mg/g (metered-dose pump): Each pump actuation delivers 1.25 g of gel containing 20.25 mg of testosterone. The standard starting dose is one pump actuation (20.25 mg testosterone) applied once daily. Dose adjustments are made in increments of one actuation:

• Starting dose: 1 actuation daily (20.25 mg)

• Titrate in steps of 1 actuation (20.25 mg) based on response

• Maximum dose: 4 actuations daily (81 mg)

Timing and consistency are important factors in dosing. Testogel should be applied at approximately the same time each day, preferably in the morning, to support the body's natural circadian rhythm of testosterone production. This consistency helps maintain stable hormone levels and optimises symptom control.

It is crucial to emphasise that dosing should never be self-adjusted without medical guidance. Your prescribing clinician will determine the appropriate starting dose and formulation based on your baseline testosterone levels, symptoms, age, and overall health status. Regular monitoring through blood tests is essential to ensure the dose remains appropriate and effective. Always follow the specific instructions for your prescribed Testogel product, as application sites and other guidance differ between formulations.

How to Apply Testogel Correctly

Proper application technique is essential to ensure optimal testosterone absorption and to minimise the risk of transferring the medication to others. Application instructions differ between the two UK Testogel formulations:

Testogel 1% (50 mg/5 g sachets):

• Apply once daily to clean, dry, intact skin on the shoulders, upper arms, or abdomen

• Spread the gel thinly over a large surface area

• Allow the gel to dry for at least 3–5 minutes before dressing

• Do not wash the application site for at least 6 hours after application

• Avoid close skin-to-skin contact with others for at least 6 hours, or until the site has been washed

Testogel 16.2 mg/g (metered-dose pump):

• Apply once daily to clean, dry, intact skin on the shoulders and upper arms only (do not apply to the abdomen)

• Spread the gel thinly over the application area

• Allow the gel to dry for at least 3–5 minutes before dressing

• Do not wash the application site or swim for at least 2 hours after application

• Cover the application site with clothing once dry; avoid close skin contact with others until the site has been washed

General application steps:

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

• Apply the gel to the designated area for your product

• Allow the gel to dry completely before dressing

• Wash your hands thoroughly with soap and water immediately after application

• Cover the application site with clothing once the gel has dried

Important safety precautions:

Do not apply Testogel to the genital area, as this can cause significant irritation. Avoid application to broken, irritated, or damaged skin. Ideally, apply the gel after your morning shower rather than before, to allow adequate time before washing.

Flammability warning: The gel contains alcohol and is flammable. Allow the gel to dry fully and keep away from naked flames and do not smoke until the gel has dried.

Preventing transfer to others is a critical safety consideration. Testosterone can be transferred through skin-to-skin contact, potentially causing virilisation in women and children (development of male characteristics such as facial hair, voice deepening, or genital changes). This risk is of particular concern for pregnant women. To prevent transfer:

• Keep the application site covered with clothing once dry

• Avoid close skin contact with partners, children, and pregnant women until the site has been washed

• Wash the application site thoroughly with soap and water before any anticipated close skin contact

• Wash any clothing or bedding that may have come into contact with the gel

If accidental contact occurs, the affected person should wash the area immediately and thoroughly with soap and water.

Adjusting Your Testogel Dose Based on Testosterone Levels

Dose adjustments are a normal and expected part of testosterone replacement therapy. Your clinician will monitor your response through regular blood tests measuring serum testosterone levels, typically conducted a few weeks after starting treatment or after any dose change, and then at regular intervals (usually every 3–6 months once stable).

The timing of blood sampling should follow your clinician's advice and may vary depending on the specific product and local laboratory protocols. Some protocols recommend sampling 2–4 hours after gel application to assess peak levels, whilst others may use pre-dose (trough) sampling. Your clinician will compare your results against the normal reference range for adult men, which typically falls between 10–30 nmol/L, though target ranges may vary slightly between laboratories and individual patient needs.

Dose increases may be considered if:

• Testosterone levels remain below the therapeutic range

• Symptoms of hypogonadism persist despite treatment

• You are tolerating the current dose well without adverse effects

For Testogel 1% sachets, increases are made in 2.5 g increments (25 mg testosterone), up to a maximum of 10 g daily (100 mg). For Testogel 16.2 mg/g pump, increases are made in steps of one actuation (20.25 mg testosterone), up to a maximum of 4 actuations daily (81 mg).

Dose reductions may be necessary if:

• Testosterone levels exceed the upper limit of normal

• You experience adverse effects such as mood changes, aggression, or skin reactions

• Haematocrit levels become elevated (increased red blood cell concentration)

Haematocrit monitoring is essential. If your haematocrit rises to 0.54 or above, your clinician will typically interrupt or reduce your dose and investigate further, as elevated haematocrit increases the risk of blood clots and cardiovascular events.

NICE guidance emphasises the importance of individualised treatment, with dose adjustments based on both biochemical parameters and clinical response. Some men achieve symptom relief with testosterone levels in the lower-normal range, whilst others require levels in the mid-to-upper normal range. Regular monitoring will also include full blood count, liver function tests, lipid profile, and prostate-specific antigen (PSA), particularly in men over 50 or those with risk factors for prostate disease.

Never adjust your dose independently. Self-adjustment can lead to supraphysiological testosterone levels, increasing the risk of cardiovascular events, polycythaemia, and other serious complications. Always consult your GP or endocrinologist before making any changes to your treatment regimen.

Common Side Effects and When to Seek Medical Advice

Like all medicines, Testogel can cause side effects, though not everyone experiences them. Understanding potential adverse effects and knowing when to seek medical attention is essential for safe treatment. The frequency and nature of side effects should be discussed with your clinician, as they can vary between individuals and may be influenced by dose and duration of treatment.

Possible side effects include:

• Skin reactions at the application site: redness, itching, dry skin, rash, or acne

• Mood and behavioural changes: irritability, aggression, mood swings, anxiety, or depression

• Headache and dizziness

• Changes in libido: either increased or decreased sexual desire

• Prostate effects: benign prostatic hyperplasia (prostate enlargement), which may cause urinary symptoms such as difficulty starting urination, weak stream, or increased frequency

• Polycythaemia: excessive red blood cell production, detected on blood tests, which increases blood viscosity and the risk of thrombosis

• Gynaecomastia: breast tissue enlargement

• Fluid retention: causing ankle swelling or weight gain

• Sleep apnoea: new onset or worsening of existing sleep-disordered breathing

• Effects on fertility: reduced sperm count and potential infertility

The frequency of these effects varies; your clinician can provide more specific information based on the UK Summary of Product Characteristics (SmPC) for your prescribed formulation.

You should contact your GP promptly if you experience:

• Persistent or severe skin reactions at the application site

• Significant mood changes, depression, or aggressive behaviour

• Urinary symptoms such as difficulty passing urine, weak stream, or increased frequency

• Unexplained weight gain or ankle swelling

• Persistent headaches or visual disturbances

• Symptoms suggesting sleep apnoea (loud snoring, breathing pauses during sleep, excessive daytime sleepiness)

Seek immediate medical attention (call 999 or attend A&E) if you develop:

• Signs of a blood clot: sudden chest pain, breathlessness, coughing up blood, or leg pain with swelling and redness

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

• Prolonged, painful erection lasting more than 4 hours (priapism)

Regular monitoring is essential and typically includes blood tests for testosterone levels, full blood count (to detect polycythaemia), haematocrit, liver function, lipid profile, and prostate-specific antigen (PSA). Men over 50 or those with risk factors for prostate disease require particularly careful monitoring. Your clinician will also assess cardiovascular risk factors. If your haematocrit reaches 0.54 or above, treatment may need to be interrupted or the dose reduced.

Reporting side effects: If you experience any side effects, including those not listed here, please report them to your clinician. You can also report suspected side effects directly via the MHRA Yellow Card scheme at www.mhra.gov.uk/yellowcard or by downloading the Yellow Card app. Reporting helps provide ongoing safety information about this medicine.

Always attend scheduled follow-up appointments and report any concerns to your healthcare provider promptly. Do not stop treatment without consulting your clinician, as sudden discontinuation may cause symptoms to return.

Frequently Asked Questions