Testogel is a testosterone replacement therapy prescribed to treat male hypogonadism, a condition where the body produces insufficient testosterone. This topical gel delivers testosterone through the skin into the bloodstream, helping restore normal hormone levels in men with confirmed testosterone deficiency. Hypogonadism can result from testicular dysfunction, pituitary disorders, or hypothalamic problems, causing symptoms such as reduced libido, fatigue, muscle loss, and mood changes. Diagnosis requires biochemical confirmation through blood tests before treatment begins. Testogel is only prescribed for adult men with medically confirmed testosterone deficiency and must be used under specialist supervision.

What Is Testogel Gel Used For?

Testogel is a testosterone replacement therapy (TRT) prescribed to treat male hypogonadism, a condition characterised by abnormally low testosterone levels in men. Testosterone is the primary male sex hormone responsible for maintaining numerous physiological functions, including sexual development, muscle mass, bone density, mood regulation, and energy levels.

The gel contains testosterone as its active ingredient and is applied topically to the skin, where it is absorbed into the bloodstream. Testogel is specifically indicated for testosterone replacement in adult males with confirmed hypogonadism, where clinical features and biochemical tests confirm testosterone deficiency. Primary hypogonadism results from testicular dysfunction, whilst secondary hypogonadism occurs when the hypothalamus or pituitary gland fails to signal adequate testosterone production.

Symptoms of low testosterone that may prompt investigation include:

• Reduced libido and erectile dysfunction

• Persistent fatigue and low energy

• Loss of muscle mass and increased body fat

• Mood changes, including depression or irritability

• Decreased bone density (osteoporosis)

• Reduced facial and body hair growth

Diagnosis requires biochemical confirmation through blood tests, typically performed in the morning when testosterone levels are naturally highest. According to NICE Clinical Knowledge Summary guidance, testosterone deficiency should be confirmed with at least two separate early-morning (ideally fasting) testosterone measurements showing levels below the normal reference range. Additional tests including luteinising hormone (LH), follicle-stimulating hormone (FSH), and sometimes prolactin are needed to determine the cause.

Before starting Testogel, reversible causes of low testosterone should be addressed, including obesity, chronic illness, and certain medications like opioids. It's important to note that Testogel is not licensed for use in women or children and should only be used under specialist supervision. Testogel suppresses sperm production and may impair fertility, so it's not suitable for men trying to conceive.

Who Can Use Testogel and When It's Prescribed

Testogel is prescribed exclusively for adult men with confirmed testosterone deficiency resulting from recognised medical conditions affecting the testes, pituitary gland, or hypothalamus. The decision to initiate testosterone replacement therapy follows thorough clinical and biochemical evaluation by a healthcare professional, often an endocrinologist or specialist in sexual health.

Conditions warranting Testogel prescription include:

• Klinefelter syndrome – a genetic condition affecting testicular development

• Pituitary disorders – tumours or damage affecting hormone production

• Testicular injury or infection – physical trauma or orchitis

• Chemotherapy or radiotherapy – treatments affecting gonadal function

• Kallmann syndrome – a congenital condition affecting puberty

While some clinicians may consider TRT for age-related testosterone decline, this is not a licensed indication and should only be considered if true hypogonadism is confirmed biochemically and symptoms are significant.

Before prescribing Testogel, clinicians must exclude contraindications and assess individual risk factors. According to the UK Summary of Product Characteristics (SmPC), Testogel is contraindicated in men with:

• Prostate cancer or breast cancer (current or suspected)

• Hypersensitivity to testosterone or gel excipients

Careful consideration and optimisation are required in men with:

• Severe cardiac, hepatic or renal insufficiency

• Benign prostatic hyperplasia with urinary obstruction

• Polycythaemia (elevated red blood cell count)

• Untreated sleep apnoea

• Cardiovascular disease

• History of thromboembolism

According to NICE guidance, baseline investigations before initiating TRT should include prostate-specific antigen (PSA) testing, full blood count (especially haemoglobin/haematocrit), liver function tests, and consideration of lipid profile based on individual risk. Digital rectal examination may be performed in men over 40 or those with risk factors for prostate disease. LH, FSH and prolactin should be measured if secondary hypogonadism is suspected.

Patients should be informed that TRT reduces fertility by suppressing spermatogenesis. Men wishing to father children should discuss fertility-preserving options and may need referral to specialist andrology services.

How to Apply Testogel Safely and Effectively

Correct application technique is essential to ensure optimal testosterone absorption whilst minimising the risk of accidental transfer to others. Testogel is available in two formulations in the UK: 50 mg/5 g (1%) gel in sachets and 16.2 mg/g gel in a pump dispenser. Application instructions differ slightly between formulations.

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

• Usual starting dose is 50 mg (one sachet) daily

• May be adjusted between 25-100 mg (½-2 sachets) based on response

• Apply to clean, dry skin on shoulders, upper arms, or abdomen

• Avoid washing the application site for approximately 6 hours

Testogel 16.2 mg/g pump:

• Usual starting dose is 40.5 mg (2 pump actuations) daily

• May be adjusted between 20.25-81 mg (1-4 actuations) based on response

• Apply only to clean, dry skin on shoulders or upper arms (not abdomen)

• Avoid washing the application site for at least 2 hours

• Prime the pump before first use by pressing 3 times (discard this gel)

Step-by-step application guidance:

1. Timing: Apply Testogel at approximately the same time each morning, preferably after showering
2. Preparation: Wash and dry your hands thoroughly before opening the sachet or using the pump
3. Application: Apply the gel to approved sites – never to the genital area
4. Technique: Spread the gel thinly and evenly over a large area; do not rub vigorously
5. Drying: Allow the gel to dry completely (3–5 minutes) before dressing
6. Hand hygiene: Wash your hands thoroughly with soap and water immediately after application

Critical safety measures to prevent testosterone transfer:

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

• Avoid skin-to-skin contact with others, especially women and children

• Shower or wash the application area before anticipated close physical contact

• Wash any area of another person's skin that accidentally contacts the gel

• Keep the gel away from children and pregnant women, as testosterone exposure can cause harm

If you miss a dose, apply it as soon as you remember on the same day. If you remember the following day, skip the missed dose and continue with your regular schedule – do not double the dose. Testogel is flammable until dry, so avoid flames, smoking, or sparks near the application site. Store sachets or pumps at room temperature, away from heat and moisture, and keep out of reach of children.

Potential Side Effects and Safety Considerations

Like all medicines, Testogel can cause side effects, though not everyone experiences them. Understanding potential adverse effects enables early recognition and appropriate management. Most side effects are mild and resolve with continued use or dose adjustment, but some require medical attention.

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

• Skin reactions at the application site – redness, itching, or dryness

• Acne or oily skin

• Mood changes or emotional lability

• Headache

• Increased red blood cell count (polycythaemia)

• Weight gain

• Prostate enlargement (benign prostatic hyperplasia)

Less common but significant side effects include:

• Gynaecomastia (breast enlargement or tenderness)

• Sleep disturbances or worsening sleep apnoea

• Fluid retention and peripheral oedema

• Changes in libido (increase or decrease)

• Elevated blood pressure

• Altered liver function tests

• Changes in cholesterol levels

• Reduced sperm production and fertility

Serious side effects requiring immediate medical attention (call 999 or go to A&E):

• Signs of blood clots – sudden chest pain, breathlessness, leg pain or swelling

• Prolonged or painful erections (priapism) lasting more than 4 hours

• Signs of liver problems – yellowing of skin or eyes, dark urine, severe abdominal pain

• Allergic reactions – difficulty breathing, facial swelling, severe rash

Important drug interactions to be aware of:

• Testogel may enhance the effect of warfarin (requiring more frequent INR monitoring)

• It may reduce insulin requirements in diabetic patients

• Combined use with corticosteroids may increase the risk of fluid retention

Regular monitoring is essential throughout Testogel treatment. Follow-up should include testosterone level measurement at 3 months after starting or adjusting the dose, then every 6–12 months. Haemoglobin/haematocrit should be checked at baseline, 3–6 months, then annually. PSA and prostate assessment should be performed according to age and risk factors. More frequent monitoring is needed if abnormalities arise.

Regarding cardiovascular safety, the MHRA advises there is no consistent evidence of increased cardiovascular risk when testosterone is used as indicated for confirmed hypogonadism, but individual cardiovascular risk factors should be discussed and monitored.

Contact your GP if you experience persistent side effects, mood changes, or any concerning symptoms. If you suspect you're experiencing a side effect from Testogel, you can report it through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Frequently Asked Questions