Testogel is a transdermal testosterone replacement therapy gel prescribed for men with confirmed hypogonadism—a condition where the testes produce insufficient testosterone. Applied daily to the skin, it delivers a steady release of testosterone to restore hormone levels and alleviate symptoms such as reduced libido, fatigue, and low mood. Proper application technique, site selection, and awareness of potential side effects are essential for safe and effective treatment. This guide explains how to use Testogel correctly, where to apply it, and when to seek medical advice, in line with UK clinical guidance from NICE, the MHRA, and the BNF.
Summary: Testogel is applied once daily to clean, dry skin on the shoulders, upper arms, or abdomen (depending on formulation), allowed to dry completely, then covered with clothing to prevent transfer to others.
- Testogel is a transdermal testosterone gel prescribed for male hypogonadism confirmed by two early-morning blood tests showing low testosterone levels.
- Apply the gel at the same time each morning to approved sites (shoulders, upper arms, or abdomen for 1% sachets; shoulders and upper arms only for pump formulation).
- Allow the gel to dry completely before dressing, avoid washing the site for at least 2–6 hours (depending on formulation), and cover with clothing to prevent transfer to others.
- Common side effects include skin irritation, mood changes, headache, and increased blood pressure; serious risks include polycythaemia, blood clots, and cardiovascular events.
- Regular monitoring with blood tests (testosterone, full blood count, PSA, liver function) is required at 3, 6, and 12 months, then annually.
- Testosterone replacement suppresses natural testosterone and sperm production; discuss fertility plans with your doctor before starting treatment.
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What Is Testogel and When Is It Prescribed?
Testogel is a transdermal testosterone replacement therapy (TRT) gel containing testosterone as the active ingredient. It is licensed in the UK for the treatment of male hypogonadism, a condition characterised by insufficient testosterone production by the testes. The gel is applied directly to the skin, where testosterone is absorbed into the bloodstream, providing a steady release of the hormone throughout the day.
Testosterone plays a crucial role in maintaining several physiological functions in men, including:
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Sexual function and libido
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Muscle mass and bone density
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Mood regulation and cognitive function
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Red blood cell production
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Fat distribution and metabolic health
Testogel is typically prescribed when blood tests confirm low testosterone levels alongside symptoms such as reduced libido, erectile dysfunction, fatigue, low mood, reduced muscle mass, or osteoporosis. According to NICE Clinical Knowledge Summaries (CKS), diagnosis should be based on two early-morning serum total testosterone measurements (taken before 11:00 am on separate occasions), ideally at least one week apart. Levels below 8 nmol/L usually indicate hypogonadism; levels between 8–12 nmol/L are borderline and may require assessment of sex hormone-binding globulin (SHBG) and calculation of free or bioavailable testosterone. Testosterone levels naturally decline with age, and not all men with lower levels require treatment.
Before initiating Testogel, your GP or endocrinologist will conduct a thorough assessment to identify the underlying cause of hypogonadism (primary testicular failure or secondary hypothalamic-pituitary dysfunction). This includes measurement of luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin; pituitary imaging may be indicated if secondary hypogonadism is suspected. A prostate examination and prostate-specific antigen (PSA) test are essential, as testosterone therapy is contraindicated in men with prostate or breast cancer.
Important fertility consideration: Testosterone replacement therapy suppresses the body's own testosterone and sperm production. If you are planning to father children, discuss this with your doctor before starting treatment, as alternative therapies may be more appropriate.
Regular monitoring is essential during treatment. According to the Summary of Product Characteristics (SmPC) and UK endocrine guidance, blood tests are typically performed at 3, 6, and 12 months initially, then annually thereafter, to check testosterone levels, full blood count (for polycythaemia), liver function, lipid profile, and PSA. The MHRA emphasises that testosterone replacement should only be used when hypogonadism has been confirmed by clinical features and biochemical tests, and treatment should be individualised based on patient response and tolerability.
How to Apply Testogel Correctly: Step-by-Step Guide
Proper application technique is essential to ensure optimal testosterone absorption and minimise the risk of transferring the gel to others. Testogel is available in two formulations in the UK, and the instructions differ slightly:
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Testogel 50 mg (1% gel in 5 g sachets): usual starting dose is 50 mg (one sachet) once daily
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Testogel 16.2 mg/g (pump dispenser): each pump actuation delivers 1.25 g of gel containing 20.25 mg of testosterone; usual starting dose is 40.5 mg (two pump actuations) once daily
Your doctor will prescribe the appropriate formulation and dose based on your testosterone levels. Follow these steps carefully when applying Testogel:
1. Timing and preparation Apply Testogel at approximately the same time each morning, preferably after showering. Ensure the skin is clean, dry, and intact (no cuts, irritation, or broken skin). Wash and dry your hands thoroughly before opening the sachet or using the pump.
2. Opening and dispensing If using sachets, tear open carefully at the notch. If using a pump dispenser, prime it according to the manufacturer's instructions before first use (usually three actuations into a waste container).
3. Application technique 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 across the designated application area (see next section for approved sites). Use gentle, smooth strokes to spread the gel—do not rub vigorously. Allow the gel to dry completely before dressing. The gel should form an invisible film once dry.
4. Post-application care Wash your hands thoroughly with soap and water immediately after application. Cover the application area with clothing (such as a T-shirt) once the gel has dried.
Important: the gel is flammable until dry. Avoid open flames, smoking, or sources of ignition until the gel has dried completely on your skin.
Avoiding washing the application site: To ensure adequate absorption, avoid washing, showering, or swimming for:
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At least 6 hours after applying Testogel 50 mg (1% sachet)
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At least 2 hours after applying Testogel 16.2 mg/g (pump)
If you must shower or swim within these periods, wait as long as possible to maximise absorption.
Preventing transfer to others: Testosterone can be transferred to other people through close skin-to-skin contact, which can cause unwanted effects, particularly in women (including signs of virilisation) and children. This is especially important if you have contact with pregnant women, as testosterone may harm the unborn baby. If direct skin-to-skin contact occurs before you have washed the application area, the other person should wash the contact area with soap and water immediately. Always cover the application site with clothing once dry, and wash the area with soap and water before any close physical contact if the site is uncovered.
Missed dose: If you forget a dose, apply it as soon as you remember on the same day; if it is nearly time for the next dose, skip the missed dose and continue as normal. Never double the dose to compensate.
Where to Apply Testogel on Your Body
The approved application sites for Testogel differ depending on which formulation you have been prescribed:
For Testogel 50 mg (1% gel, sachet): Apply to clean, dry, healthy skin on the shoulders, upper arms, or abdomen. Spread the gel over an area roughly equivalent to two palm sizes. You may use one or a combination of these sites.
For Testogel 16.2 mg/g (pump): Apply to clean, dry, healthy skin on the shoulders and upper arms only. The abdomen is not a licensed application site for this formulation. Distribute the gel evenly across the outer aspect of both shoulders and upper arms.
Areas to avoid (both formulations): Do not apply Testogel to:
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The genital area or scrotum (risk of local irritation and inappropriate absorption)
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Broken, irritated, or inflamed skin
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The chest (not a licensed application site)
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Areas that will be subject to friction or pressure immediately after application (e.g., under a tight waistband)
For optimal results, you may rotate application sites within the approved areas to help prevent skin irritation. For example, alternate between left and right shoulders/arms on different days, or (for the 1% sachet only) vary between shoulders, arms, and abdomen. The skin should appear normal before each application; if you notice persistent redness, itching, or irritation at application sites, contact your GP or prescribing clinician.
Preventing transfer to others is crucial. Once the gel has dried, cover the application sites with clothing (such as a T-shirt). This is particularly important if you have close physical contact with partners, children, or pregnant women. If you anticipate close skin-to-skin contact, wash the application area with soap and water beforehand. If accidental contact occurs, the other person should wash the affected area immediately with soap and water.
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 advice is essential for safe treatment.
Common side effects (frequency varies by formulation; consult the patient information leaflet supplied with your medicine) include:
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Skin reactions at application site: redness, itching, dry skin, acne, rash, or irritation
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Mood and behavioural changes: increased aggression, irritability, mood swings, anxiety, or depression
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Headache and dizziness
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Increased blood pressure
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Prostate changes: elevated PSA levels, prostate enlargement (benign prostatic hyperplasia), or urinary symptoms
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Changes in libido: either increased or, less commonly, decreased sexual desire
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Gynaecomastia: breast tenderness or enlargement
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Fluid retention: ankle swelling or weight gain
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Hot flushes
Less common but significant side effects include:
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Polycythaemia (increased red blood cell count): This can thicken the blood and increase the risk of blood clots and cardiovascular events. Your doctor will monitor your haematocrit (the proportion of red blood cells in your blood) through regular blood tests. According to UK endocrine guidance, a haematocrit above 0.54 (54%) may require dose reduction or temporary cessation of treatment.
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Sleep apnoea: worsening of existing sleep-disordered breathing or new onset of symptoms
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Liver function changes: detected through blood tests
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Hair loss or increased body hair growth
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Venous thromboembolism (VTE): blood clots in the legs or lungs
Drug interactions: Testogel may interact with other medicines. In particular:
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Anticoagulants (e.g., warfarin): Testosterone may increase their effect, raising bleeding risk; your INR may need closer monitoring.
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Insulin and oral antidiabetic medicines: Testosterone may reduce blood glucose levels, potentially requiring dose adjustment of diabetes medicines.
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Corticosteroids or ACTH: Concurrent use may increase the risk of fluid retention and oedema.
Always inform your doctor or pharmacist of all medicines you are taking, including over-the-counter products and herbal supplements.
When to contact your GP or healthcare provider:
Arrange a routine appointment if you experience persistent skin irritation, mood changes, or any side effects that concern you. Attend all scheduled follow-up appointments and monitoring blood tests to ensure treatment remains safe and effective.
Seek urgent medical advice if you develop:
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Chest pain, shortness of breath, or signs of blood clots: leg pain, swelling, warmth, redness, or sudden breathlessness
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Severe allergic reactions: facial swelling, difficulty breathing, or widespread rash
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Prolonged or painful erections (priapism) lasting more than 4 hours—this requires immediate medical attention
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Signs of liver problems: yellowing of the skin or eyes (jaundice), dark urine, pale stools, or severe abdominal pain
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Significant mood disturbances: severe depression, aggression, or thoughts of self-harm
According to the MHRA Drug Safety Update, testosterone replacement therapy should only be used in men with confirmed hypogonadism. While appropriate testosterone replacement in hypogonadal men has not been shown to increase cardiovascular risk, men with pre-existing cardiovascular disease require careful monitoring. There is a risk of venous thromboembolism, particularly in men with other risk factors.
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 medicines.
Frequently Asked Questions
Can I shower or swim after applying Testogel?
You should avoid washing, showering, or swimming for at least 6 hours after applying Testogel 50 mg (1% sachet) or at least 2 hours after applying Testogel 16.2 mg/g (pump) to ensure adequate absorption.
Can Testogel be transferred to other people?
Yes, testosterone can transfer through close skin-to-skin contact, potentially causing unwanted effects in women and children. Always cover the application site with clothing once dry and wash the area with soap and water before close physical contact.
How often do I need blood tests while using Testogel?
Blood tests to monitor testosterone levels, full blood count, PSA, and liver function are typically required at 3, 6, and 12 months after starting treatment, then annually thereafter to ensure safe and effective therapy.
The health-related content published on this site is based on credible scientific sources and is periodically reviewed to ensure accuracy and relevance. Although we aim to reflect the most current medical knowledge, the material is meant for general education and awareness only.
The information on this site is not a substitute for professional medical advice. For any health concerns, please speak with a qualified medical professional. By using this information, you acknowledge responsibility for any decisions made and understand we are not liable for any consequences that may result.
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