Testogel is a prescription testosterone replacement therapy used to treat male hypogonadism, a condition where the body cannot produce adequate testosterone. Understanding the reasons for using Testogel is essential for men experiencing symptoms of low testosterone. This gel-based treatment is prescribed only after blood tests confirm testosterone deficiency alongside relevant clinical symptoms. Testogel works by delivering testosterone through the skin, helping to restore hormone levels and alleviate symptoms affecting sexual function, physical health, and psychological wellbeing. This article explores the medical indications, symptoms treated, safety considerations, and proper use of Testogel in the UK.

What Is Testogel and How Does It Work?

Testogel is a transdermal testosterone replacement therapy (TRT) available on prescription in the UK for men with confirmed testosterone deficiency. It contains testosterone as the active ingredient, formulated as a clear or slightly opalescent gel that is applied directly to the skin.

The gel works through transdermal absorption, allowing testosterone to pass through the skin and into the bloodstream gradually over 24 hours. Once absorbed, testosterone is distributed throughout the body where it binds to androgen receptors in various tissues, including muscle, bone, and the central nervous system. This provides relatively stable blood levels throughout the day.

Testosterone is the primary male sex hormone (androgen) responsible for developing and maintaining male characteristics. In adult men, it plays crucial roles in:

• Maintaining muscle mass and bone density

• Regulating libido and sexual function

• Supporting mood and cognitive function

• Influencing fat distribution and red blood cell production

Testogel is available in two formulations in the UK: 1% sachets (50 mg per 5 g sachet) and 16.2 mg/g pump. Each has specific application instructions and dosing recommendations. The gel formulation offers several advantages over other testosterone delivery methods. Unlike intramuscular injections, which can cause fluctuating testosterone levels, Testogel can provide more consistent hormone levels. It is also non-invasive and can be self-administered at home.

Important safety notes: The gel is flammable until dry, so avoid smoking or naked flames during application. There are also specific precautions regarding skin-to-skin contact with others, particularly women and children, to prevent unintended testosterone transfer.

Medical Reasons for Using Testogel

Testogel is prescribed specifically for male hypogonadism, a clinical condition characterised by the body's inability to produce adequate amounts of testosterone. This diagnosis must be confirmed through blood tests showing consistently low testosterone levels alongside relevant clinical symptoms.

Diagnosis requires at least two early-morning blood samples (ideally taken between 8-10am when testosterone is naturally highest), preferably when fasting and not during acute illness. Laboratory reference ranges vary, and borderline results may require additional testing of sex hormone binding globulin (SHBG) and calculated free testosterone.

Primary hypogonadism occurs when the testes themselves fail to produce sufficient testosterone due to:

• Genetic conditions such as Klinefelter syndrome

• Testicular injury or infection (orchitis)

• Chemotherapy or radiotherapy affecting the testes

• Undescended testes (cryptorchidism) that were not corrected in childhood

Secondary hypogonadism results from problems with the hypothalamus or pituitary gland, which normally signal the testes to produce testosterone. Causes include:

• Pituitary tumours or damage from surgery/radiotherapy

• Kallmann syndrome (a genetic condition affecting hormone production)

• Chronic illnesses affecting the hypothalamic-pituitary axis

• Certain medications, particularly opioids and corticosteroids

According to NICE Clinical Knowledge Summaries, testosterone replacement should only be initiated after thorough investigation to identify the underlying cause of hypogonadism and exclude other treatable conditions. Blood tests should include not only testosterone levels but also luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin to distinguish between primary and secondary causes. Secondary hypogonadism typically requires referral to an endocrinologist for further investigation, including possible pituitary imaging.

It is important to note that Testogel is not licensed for treating age-related decline in testosterone (sometimes called 'andropause' or late-onset hypogonadism) unless there is a clear pathological cause. The normal age-related decline in testosterone does not automatically warrant treatment, and lifestyle modifications should be considered first. Testogel is also not appropriate for enhancing athletic performance or bodybuilding, and such use is both illegal and potentially harmful.

Symptoms of Low Testosterone That Testogel Treats

Men with clinically significant testosterone deficiency may experience a range of symptoms affecting physical, sexual, and psychological wellbeing. Testogel aims to alleviate these symptoms when they are directly attributable to confirmed low testosterone levels.

Sexual symptoms are often the most noticeable and include:

• Reduced libido (sex drive)

• Erectile dysfunction or difficulty maintaining erections

• Decreased spontaneous erections, particularly morning erections

Important note: Testosterone replacement therapy (TRT) typically reduces sperm production and should not be used to treat fertility problems. Men wishing to father children should discuss this with their doctor, as alternative treatments may be more appropriate.

Physical symptoms that may improve with testosterone replacement include:

• Loss of muscle mass and strength

• Increased body fat, particularly around the abdomen

• Reduced bone density (osteoporosis or osteopenia), increasing fracture risk

• Decreased body hair growth

• Persistent fatigue and reduced physical stamina

• Hot flushes or sweating episodes

Note: Gynaecomastia (breast tissue enlargement) may have multiple causes and should be evaluated separately. Testosterone therapy can sometimes worsen this condition rather than improve it.

Psychological and cognitive symptoms associated with low testosterone include:

• Low mood or depressive symptoms

• Irritability and mood swings

• Poor concentration and memory difficulties

• Reduced motivation and self-confidence

• Sleep disturbances

It is crucial to understand that these symptoms are non-specific and can result from numerous other medical conditions, including thyroid disorders, diabetes, depression, sleep apnoea, and cardiovascular disease. Therefore, a comprehensive medical assessment is essential before attributing symptoms solely to testosterone deficiency.

Response to Testogel varies between individuals. Some men notice improvements in energy, mood, and libido within 3–6 weeks, whilst changes in muscle mass, bone density, and body composition typically require 3–6 months of consistent treatment. If symptoms do not improve after an adequate trial period (usually 3–6 months), the diagnosis should be reconsidered, and alternative causes investigated.

Who Should Not Use Testogel

Testogel has several absolute and relative contraindications that must be carefully considered before initiating treatment. Healthcare professionals will assess individual risk factors to determine suitability.

Absolute contraindications (Testogel must not be used) include:

• Known or suspected prostate cancer or breast cancer (current or previous)

• Severe hepatic or renal insufficiency

• Severe heart failure (NYHA Class IV)

• Hypersensitivity to testosterone or any gel excipients

Relative contraindications (requiring careful assessment and monitoring) include:

• Elevated prostate-specific antigen (PSA) levels requiring investigation

• Benign prostatic hyperplasia (BPH) with significant urinary symptoms

• Polycythaemia (elevated red blood cell count with haematocrit >0.54)

• Sleep apnoea, which may worsen with testosterone therapy

• Cardiovascular disease, including previous heart attack or stroke

• Hypertension (high blood pressure)

• Epilepsy or migraine, as testosterone may affect seizure threshold

• Kidney or liver disease (mild to moderate)

• History of blood clots (thromboembolism) or thrombophilia

Special populations requiring caution:

Testogel is not indicated for use in women or children/adolescents and should never be used during pregnancy or breastfeeding due to potential virilisation of female foetuses and infants.

Elderly men require particularly careful assessment, as they have higher rates of prostate disease and cardiovascular conditions. The MHRA advises regular monitoring of haematocrit in all patients, as testosterone can stimulate red blood cell production, potentially increasing cardiovascular risk. Treatment should be withheld or stopped if haematocrit exceeds 0.54.

Before prescribing Testogel, doctors should perform:

• Digital rectal examination and PSA testing to screen for prostate abnormalities

• Full blood count to check for polycythaemia

• Liver function tests

• Lipid profile and cardiovascular risk assessment

Patients should inform their healthcare provider of all medications they are taking, as testosterone can interact with anticoagulants (such as warfarin), antidiabetic drugs, and corticosteroids.

How to Use Testogel Safely and Effectively

Proper application technique is essential for optimal absorption and to prevent accidental transfer to others. Testogel should be applied once daily, preferably at the same time each morning, to clean, dry, intact skin.

Application instructions vary by formulation:

For Testogel 1% (50 mg sachets):

• Apply to shoulders, upper arms, or abdomen

• Starting dose is typically one 5 g sachet (50 mg) daily

For Testogel 16.2 mg/g (pump):

• Apply only to shoulders and upper arms (not abdomen)

• Starting dose is typically 2 pump actuations (40.5 mg) daily

For both formulations:

• Spread the gel thinly over the application area

• Wash hands thoroughly with soap and water immediately after application

• Allow the gel to dry completely before dressing (3-5 minutes)

• Cover the application site with clothing once dry

• Follow the specific washing/showering instructions in your patient information leaflet

• Keep away from fire, flames or smoking until the gel has dried (it is flammable)

Preventing transfer to others is critically important, as testosterone exposure can cause serious adverse effects in women and children, including virilisation (development of male characteristics). To minimise risk:

• Avoid skin-to-skin contact with others at the application site

• Wash the application area thoroughly before any situation involving close physical contact

• Ensure children do not touch the application site

• If someone else contacts the gel, they should wash the area immediately with soap and water

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

Monitoring and follow-up:

Regular monitoring is essential to ensure treatment effectiveness and safety. Your GP or endocrinologist will typically arrange:

• Testosterone level checks at 3 months, then 6–12 monthly (aiming for mid-normal range)

• PSA testing and prostate examination annually (for men over 40 or at higher risk)

• Full blood count to monitor haematocrit every 3–6 months initially, then annually

• Treatment should be paused or stopped if haematocrit exceeds 0.54

• Liver function tests periodically

• Bone density scans if osteoporosis was present initially

When to seek medical advice:

Contact your GP promptly if you experience:

• Difficulty urinating or changes in urinary flow

• Breast lumps or tenderness

• Prolonged or painful erections (priapism)

• Ankle swelling or unexplained weight gain

• Mood changes, aggression, or depression

• Signs of blood clots (leg pain, swelling, chest pain, breathlessness)

Missed doses: 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. Do not apply a double dose.

Testogel is a long-term treatment for a chronic condition. Do not stop using it without consulting your doctor, as symptoms may return. Regular review ensures that treatment remains appropriate and beneficial for your individual circumstances.

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

Frequently Asked Questions