Testogel is a topical testosterone replacement therapy prescribed for men with confirmed testosterone deficiency (hypogonadism). Correct application technique is essential for optimal absorption and safety. The gel must be applied to specific body sites depending on your formulation: Testogel 1% may be used on shoulders, upper arms, or abdomen, whilst Testogel 16.2 mg/g should only be applied to shoulders and upper arms. Applying the gel to the wrong areas—particularly the genital region—can cause excessive absorption, irritation, and unpredictable hormone levels. This guide explains where to rub Testogel, how to apply it correctly, and the safety precautions you must follow to prevent accidental transfer to others.

What Is Testogel and How Does It Work?

Testogel is a topical testosterone replacement therapy (TRT) licensed in the UK for treating male hypogonadism—a condition where the testes produce insufficient testosterone. It is available in two formulations: Testogel 1% (50 mg sachets) and Testogel 16.2 mg/g (pump dispenser). Other UK testosterone gels include Testavan 2% and Tostran 2%. The gel is applied directly to the skin once daily, usually in the morning, to mimic the body's natural circadian rhythm of testosterone production.

The active ingredient, testosterone, is absorbed through the skin into the bloodstream over several hours following application. Once absorbed, it supplements the body's endogenous testosterone levels, helping to restore normal physiological concentrations. This transdermal route bypasses first-pass hepatic metabolism, offering a more stable pharmacokinetic profile. Oral testosterone undecanoate is not currently marketed in the UK; historically, 17α-alkylated oral testosterone preparations were withdrawn due to hepatotoxicity concerns.

Testogel is indicated for men with confirmed testosterone deficiency, diagnosed through clinical symptoms (such as reduced libido, erectile dysfunction, fatigue, loss of muscle mass, and mood disturbances) alongside consistently low serum testosterone levels. According to NICE Clinical Knowledge Summaries (CKS) and the British National Formulary (BNF), diagnosis requires at least two separate fasting morning (8–11 am) testosterone measurements showing low levels, plus measurement of luteinising hormone (LH), follicle-stimulating hormone (FSH), and, where appropriate, prolactin. Secondary causes of hypogonadism must be excluded, and contraindications such as prostate or breast cancer ruled out before initiating treatment.

Important fertility consideration: Testosterone replacement therapy suppresses spermatogenesis and can impair fertility. Men who are planning to conceive should not use TRT; specialist referral to endocrinology or reproductive medicine is advised for alternative management.

Typical starting doses are Testogel 1%: 50 mg daily (one sachet) or Testogel 16.2 mg/g: 40.5 mg daily (two pump actuations), with titration based on individual response and follow-up blood tests. Patients should be monitored regularly—at baseline, 3 months, 6 months, then annually—to assess symptom improvement, serum testosterone levels (measured 2–4 hours post-application for dose adjustment), haematocrit/haemoglobin, prostate-specific antigen (PSA) and digital rectal examination (DRE) as appropriate for age and risk, and blood pressure. Liver function tests are not routinely required unless clinically indicated. Proper application technique is essential to ensure optimal absorption and therapeutic efficacy whilst minimising the risk of transfer to others.

Where to Apply Testogel: Recommended Application Sites

The recommended application sites for testosterone gels vary by product. It is essential to follow the instructions specific to your prescribed formulation, as detailed in the electronic Medicines Compendium (eMC) Summary of Product Characteristics (SmPC) for each gel.

For Testogel 1% (50 mg sachets): Apply to clean, dry, intact skin on the shoulders, upper arms, or abdomen. These areas provide adequate surface area for absorption and are easily covered by clothing, reducing the risk of accidental transfer to others.

For Testogel 16.2 mg/g (pump): Apply to clean, dry, intact skin on the shoulders and upper arms only. Do not apply to the abdomen with this formulation.

For Testavan 2%: Apply to the shoulders and upper arms only.

For Tostran 2%: Apply to the abdomen or inner thighs.

Shoulders and upper arms (where permitted by your product) should be treated by applying the gel to the outer aspect of the shoulders and the upper arms, spreading it thinly over a large enough area to allow proper absorption. These sites are generally less prone to friction from clothing and offer good bioavailability.

The abdomen (for Testogel 1% only) should be treated by spreading the gel over a wide area, typically from the waistline to just below the ribcage, avoiding the genital area.

Areas to avoid for all testosterone gels include:

• The genital area (scrotum and penis), as this can cause excessive absorption and local irritation

• Broken, irritated, or damaged skin, which may alter absorption rates and cause discomfort

• Oily or recently moisturised skin, which can impair absorption

• Areas where the gel may be easily rubbed off by tight clothing or frequent contact

Patients should rotate application sites within the recommended areas for their product to help prevent skin irritation. If skin reactions develop at one site, use alternative approved areas for that formulation. Consistent use of the correct application sites helps maintain stable testosterone levels and reduces transfer risk.

Step-by-Step Guide to Applying Testogel Correctly

Proper application technique is crucial for ensuring optimal testosterone absorption and minimising safety risks. Follow these steps carefully each time you apply your testosterone gel:

1. Timing and preparation: Apply your gel at approximately the same time each morning, preferably after showering. Ensure the application site is completely clean, dry, and free from any lotions, oils, or other topical products. Wash and dry your hands thoroughly before opening the product.

2. Opening the product: For sachets, tear open carefully at the notch. For pump dispensers, prime the device as instructed in the patient information leaflet (usually 3 pumps discarded on first use). For tubes, remove the cap and ensure the seal is intact.

3. Dispensing the correct dose: Squeeze the entire contents of the sachet, or depress the pump the prescribed number of times, into the palm of one hand. Do not apply directly from the container to your body. Typical doses are:

• Testogel 1%: Usually one sachet (50 mg) daily; may be increased to two sachets (100 mg) if needed, but do not exceed 100 mg/day.

• Testogel 16.2 mg/g: Usually two to three pump actuations (40.5–60.75 mg) daily; maximum four actuations (81 mg).

Never adjust your dose without medical guidance.

4. Application technique: Using your hand, spread the gel thinly and evenly over the recommended application site(s) for your product. Cover a large surface area—approximately the size of two palms—rather than applying thickly to a small area. Do not rub the gel in vigorously; gentle spreading is sufficient. The gel should form a thin, transparent film that will dry within a few minutes.

5. Drying time and flammability warning: Allow the gel to dry completely on your skin before dressing. This typically takes 3–5 minutes. The gel is flammable until dry; avoid open flames, smoking, or sources of ignition during this time. Do not cover the area until it is fully dry.

6. Avoiding water contact: Do not shower, bathe, or swim for a specified period after application:

• Testogel 1%: Avoid water contact for at least 6 hours.

• Testogel 16.2 mg/g, Testavan 2%, Tostran 2%: Avoid water contact for at least 2 hours.

Check your product information leaflet for the specific interval for your gel.

7. Hand hygiene: Immediately after application, wash your hands thoroughly with soap and water to remove any residual testosterone. This is essential to prevent accidental transfer to others through hand contact.

8. Monitoring blood levels: When starting treatment or adjusting your dose, your doctor will measure your serum testosterone level 2–4 hours after application to guide dose titration.

Common Mistakes to Avoid When Using Testogel

Several common errors can compromise the effectiveness of testosterone gels or increase safety risks. Being aware of these pitfalls helps ensure optimal treatment outcomes:

Applying to incorrect body sites is a frequent mistake. Always use the sites approved for your specific product: Testogel 1% may be applied to shoulders, arms, or abdomen; Testogel 16.2 mg/g, Testavan 2% to shoulders and upper arms only; Tostran 2% to abdomen or inner thighs. Never apply any testosterone gel to the genital area, as this can cause excessive local absorption, irritation, and unpredictable systemic levels. Similarly, avoid applying to areas that will be covered by tight-fitting clothing or sports equipment that may rub the gel off before absorption is complete.

Insufficient drying time before dressing is another common error. Covering the application site too quickly can transfer testosterone to clothing, reducing the absorbed dose and potentially exposing others who handle the garments. Always wait until the gel is completely dry and forms an invisible film on the skin. Remember that the gel is flammable until dry.

Showering or swimming too soon after application significantly reduces testosterone absorption. Follow the product-specific water-contact interval:

• Testogel 1%: Wait at least 6 hours.

• Testogel 16.2 mg/g, Testavan 2%, Tostran 2%: Wait at least 2 hours.

If you must shower earlier, try to avoid direct water contact with the application site, though this is not ideal. Plan your application time to accommodate the required waiting period.

Inconsistent application timing can lead to fluctuating testosterone levels. Applying at different times each day disrupts the steady-state pharmacokinetics that testosterone gels are designed to provide. Establish a consistent morning routine to maintain stable hormone levels.

Failing to wash hands thoroughly after application poses a serious risk of transferring testosterone to partners, children, or other household members through direct skin contact. This is particularly concerning for women and children, who may develop signs of virilisation (unwanted male characteristics) from repeated exposure. The MHRA Drug Safety Update emphasises the importance of hand washing and covering the application site.

Adjusting your dose without medical guidance can result in suboptimal treatment or adverse effects. Never use more or less gel than prescribed. Using more gel does not necessarily improve symptoms and may increase the risk of adverse effects such as polycythaemia (elevated red blood cell count), cardiovascular events, or mood changes. Dose adjustments should only be made following blood tests and consultation with your prescribing clinician.

What to Do After Applying Testogel: Safety Precautions

After applying testosterone gel, several important safety measures must be observed to protect both yourself and others from potential risks associated with testosterone exposure.

Covering the application site is essential once the gel has dried completely. Wear a shirt or clothing that fully covers the treated area, particularly if you anticipate close physical contact with others. This barrier significantly reduces the risk of testosterone transfer through skin-to-skin contact. Wash the application site with soap and water before any anticipated prolonged skin-to-skin contact, including sexual activity or close contact with children. If direct skin contact with the unwashed application site does occur, the affected person should wash the contact area immediately with soap and water.

Avoiding transfer to others is critical. Testosterone transfer can cause virilisation in women (including increased body hair, voice deepening, menstrual irregularities, and clitoral enlargement) and premature sexual development in children (early puberty, aggressive behaviour, enlarged genitals). If a child or woman accidentally comes into contact with the application site, wash the affected area thoroughly with soap and water. Seek medical advice promptly if signs of testosterone exposure develop. Clothing that has been in contact with wet gel should be washed before being worn by others.

Flammability precaution: The gel is flammable until dry. Avoid open flames, smoking, or sources of ignition until the application site is completely dry and covered.

Monitoring for adverse effects is an ongoing responsibility. Common side effects include skin reactions at the application site (redness, itching, or irritation), acne, and mood changes. More serious concerns require prompt medical attention.

Contact your GP or seek medical advice if you experience:

• Persistent skin reactions that don't resolve with site rotation

• Ankle swelling or unexplained weight gain (may indicate fluid retention)

• Mood changes, increased aggression, anxiety, or depression

• Difficulty urinating, increased urinary frequency, or weak urinary stream

• Headaches, dizziness, or visual disturbances (may indicate polycythaemia)

• Shortness of breath, particularly when lying flat, or excessive snoring (may indicate sleep apnoea)

Seek urgent medical attention (call 999 or go to A&E) if you experience:

• Chest pain, pressure, or tightness

• Sudden shortness of breath or difficulty breathing

• Sudden weakness, numbness, or difficulty speaking (possible stroke)

• Painful, prolonged erection lasting more than 4 hours (priapism)

Important monitoring thresholds and actions:

• Haematocrit >0.54 (54%): Treatment should be paused and specialist advice sought, as this increases the risk of thrombotic events.

• PSA rise >1.4 ng/mL within 12 months or abnormal digital rectal examination: Urgent urology referral is required as per NICE guideline NG12 (Suspected cancer: recognition and referral).

• Blood pressure: Should be monitored at each review; treat hypertension as per standard guidance.

Regular follow-up appointments are essential for monitoring treatment efficacy and safety through blood tests (testosterone levels, haematocrit/haemoglobin, PSA) and clinical assessment. Do not stop or change your dose without medical advice, as symptoms of hypogonadism may recur if treatment is discontinued.

Reporting side effects: If you experience any side effects, talk to your doctor or pharmacist. You can also report suspected side effects directly via the MHRA Yellow Card Scheme at www.mhra.gov.uk/yellowcard or search for 'MHRA Yellow Card' in the Google Play or Apple App Store. Reporting helps provide more information on the safety of this medicine.

Frequently Asked Questions