Testogel is a prescription-only testosterone gel licensed in the UK exclusively for treating hypogonadism—a medical condition characterised by insufficient testosterone production. It is not approved for bodybuilding, athletic enhancement, or cosmetic muscle building. Using Testogel without medical supervision for performance purposes is both illegal and dangerous, exposing individuals to serious cardiovascular, endocrine, and psychiatric risks. Testosterone is a Class C controlled substance, and obtaining it without a valid prescription typically involves illegal supply. This article explains why Testogel should never be used for bodybuilding, outlines the health risks of unsupervised use, and provides evidence-based alternatives for safe, sustainable muscle development.

What Is Testogel and How Does It Work?

Testogel is a prescription-only medicine (POM) licensed in the UK for treating hypogonadism—a medical condition in which the body produces insufficient testosterone. It contains testosterone as the active ingredient, delivered through a clear, colourless gel applied once daily to clean, dry skin. The approved application sites depend on the formulation: Testogel 16.2 mg/g gel should be applied to the upper arms and shoulders only, whilst the 50 mg/5 g sachet formulation may also be applied to the abdomen, as specified in the Summary of Product Characteristics (SmPC). The hormone is absorbed through the skin into the bloodstream, where it supplements naturally low testosterone levels.

The mechanism of action involves testosterone binding to androgen receptors in various tissues throughout the body. This triggers physiological processes including protein synthesis in muscle tissue, bone density maintenance, red blood cell production, and regulation of libido and mood. In men with clinically diagnosed hypogonadism, Testogel helps restore testosterone to normal physiological ranges (typically interpreted in the context of laboratory-specific reference ranges and clinical symptoms), alleviating symptoms such as fatigue, reduced muscle mass, low mood, and sexual dysfunction.

It is crucial to understand that Testogel is not licensed or intended for bodybuilding, athletic enhancement, or cosmetic muscle building. The Medicines and Healthcare products Regulatory Agency (MHRA) has approved it solely for therapeutic use in men with confirmed testosterone deficiency. Testosterone is a Class C controlled substance under the Misuse of Drugs Act 1971 and Schedule 4 Part II of the Misuse of Drugs Regulations 2001. Whilst simple possession for personal use is not an offence, supplying, importing, or exporting testosterone without authority is illegal and carries significant penalties. Obtaining a prescription-only medicine without a valid prescription typically involves illegal supply.

Healthcare professionals prescribe Testogel only after comprehensive blood tests confirm low testosterone levels on at least two separate occasions (taken in the morning when levels peak), alongside clinical symptoms. The dosage is carefully titrated to achieve normal physiological levels—not the supraphysiological concentrations sought in performance enhancement, which carry substantial health risks. Key safety precautions include avoiding secondary transfer to partners or children (by washing hands after application, allowing the gel to dry, covering the application site, and avoiding skin-to-skin contact until after washing or showering). Testogel is contraindicated in men with known or suspected prostate or breast cancer, and baseline assessment should include prostate-specific antigen (PSA) testing and digital rectal examination (DRE) as appropriate, haematocrit, liver function tests, and lipid profile. It is not licensed for use in women or children and is not a fertility treatment; testosterone replacement therapy (TRT) can suppress sperm production.

Risks of Using Testogel Without Medical Supervision

Using Testogel for bodybuilding without medical supervision exposes individuals to serious health risks. When testosterone is used at doses higher than therapeutic levels, or in individuals with normal testosterone production, the body's delicate hormonal balance is disrupted, triggering a cascade of adverse effects.

Cardiovascular complications represent one of the most significant dangers. Supraphysiological testosterone levels can increase haematocrit (red blood cell concentration), raising blood viscosity and the risk of thromboembolism, stroke, and myocardial infarction. Studies have shown associations between non-prescribed testosterone use and increased cardiovascular events, particularly in men with pre-existing risk factors. Testosterone can also adversely affect lipid profiles, reducing HDL ("good") cholesterol whilst increasing LDL cholesterol, further elevating cardiovascular risk. Regular monitoring of haematocrit is essential; therapy should be paused or adjusted if haematocrit exceeds 54%, and underlying causes should be evaluated.

Endocrine disruption is inevitable with unsupervised use. The hypothalamic-pituitary-gonadal (HPG) axis responds to exogenous testosterone by suppressing natural production. This negative feedback mechanism causes testicular atrophy, reduced sperm production (potentially leading to infertility), and dependence on external testosterone. Upon cessation, users may experience prolonged hypogonadism, requiring medical intervention to restore natural hormone production.

Other significant risks include:

• Prostate complications: Testosterone replacement therapy is contraindicated in men with known or suspected prostate or breast cancer. Prostate-specific antigen (PSA) and digital rectal examination should be performed at baseline and monitored regularly according to clinical guidelines.

• Psychiatric effects: Mood swings, aggression, anxiety, and potential for dependence

• Dermatological issues: Severe acne, oily skin, and accelerated male pattern baldness

• Gynaecomastia: Breast tissue development due to testosterone conversion to oestrogen

• Sleep apnoea: Testosterone therapy may worsen obstructive sleep apnoea; assessment is needed if symptoms develop

• Secondary transfer risk: Unintentional transfer of testosterone to partners or children through skin contact can cause virilisation in women and children; strict application and hygiene precautions are essential

It is important to note that transdermal testosterone gels bypass first-pass hepatic metabolism and carry a low risk of liver toxicity. Significant hepatotoxicity is primarily associated with 17α-alkylated oral anabolic steroids, not standard testosterone gels or injectables.

Without regular monitoring of blood parameters (testosterone levels, haematocrit, lipids, liver function, PSA), these complications can progress undetected. The MHRA and NHS strongly advise against using any prescription medication without proper medical assessment and ongoing supervision. If you experience any suspected side effects from testosterone therapy, report them via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.

Safe Alternatives to Testosterone Gel for Muscle Building

For individuals seeking to build muscle mass and improve physical performance, evidence-based, safe alternatives exist that do not involve prescription medications or hormonal manipulation. These approaches are supported by robust scientific evidence and endorsed by sports medicine professionals.

Resistance training remains the cornerstone of muscle development. Progressive overload—gradually increasing weight, repetitions, or training volume—stimulates muscle protein synthesis and hypertrophy. The UK Chief Medical Officers' Physical Activity Guidelines recommend that adults engage in muscle-strengthening activities on at least two days per week. Working with qualified personal trainers or strength and conditioning coaches ensures proper technique, reducing injury risk whilst maximising results. Structured programmes incorporating compound movements (squats, deadlifts, bench press) alongside isolation exercises produce significant muscle gains over time.

Optimised nutrition is equally critical. For healthy adults engaged in regular resistance training, sports nutrition evidence suggests protein intake of approximately 1.6–2.2 g per kilogram of body weight daily may support muscle repair and growth. However, this is not a universal NHS or NICE recommendation, and individuals with kidney disease or other medical conditions should seek personalised advice from a registered dietitian. Whole food sources including lean meats, fish, eggs, dairy, legumes, and plant-based proteins should form the foundation. Carbohydrates fuel training performance, whilst healthy fats support hormone production. The NHS Eatwell Guide provides balanced dietary advice for the general population.

Evidence-based supplements may offer modest benefits when combined with proper training and nutrition:

• Creatine monohydrate: The most researched sports supplement, shown to enhance strength and muscle mass

• Whey protein: Convenient protein source supporting muscle protein synthesis

• Vitamin D: UK guidance recommends that adults consider taking a daily supplement containing 10 micrograms of vitamin D during autumn and winter; optimising vitamin D status may support muscle function, particularly if deficiency is present

• Omega-3 fatty acids: Evidence for a direct role in muscle hypertrophy is limited, though omega-3s may help reduce exercise-induced inflammation

If you are a competitive athlete, be aware of supplement contamination risks and anti-doping regulations. Consider using third-party tested products (e.g., Informed-Sport certified) and consult UK Anti-Doping (UKAD) and World Anti-Doping Agency (WADA) guidance.

Adequate recovery, including 7–9 hours of quality sleep nightly, allows muscle repair and growth. Sleep deprivation impairs protein synthesis and can reduce natural testosterone production. Stress management through mindfulness, yoga, or other relaxation techniques also supports optimal hormonal balance and training adaptation.

These approaches, whilst requiring patience and consistency, produce sustainable results without the health risks or legal implications associated with misusing prescription medications.

When to Speak to Your GP About Low Testosterone

Whilst using Testogel for bodybuilding is inappropriate and dangerous, legitimate testosterone deficiency (hypogonadism) is a recognised medical condition requiring proper diagnosis and treatment. Understanding when to seek medical advice is important for men experiencing genuine symptoms of low testosterone.

Consider consulting your GP if you experience multiple persistent symptoms including:

• Unexplained fatigue and reduced energy levels despite adequate sleep

• Decreased libido and erectile dysfunction

• Loss of muscle mass and strength despite regular exercise

• Increased body fat, particularly around the abdomen

• Mood changes including low mood, irritability, or poor concentration

• Reduced bone density or unexplained fractures

• Hot flushes or night sweats

It is important to recognise that these symptoms are non-specific and can result from numerous other conditions including thyroid disorders, diabetes, depression, sleep apnoea, obesity, or medication side effects. Your GP will conduct a thorough assessment to exclude other causes before considering testosterone deficiency.

Diagnosis requires biochemical confirmation through blood tests. According to NICE Clinical Knowledge Summaries (CKS), at least two separate early-morning (ideally between 7–11 am) total testosterone measurements should be obtained, as levels fluctuate throughout the day. A total testosterone level below 8 nmol/L alongside clinical symptoms typically indicates hypogonadism, whilst levels between 8–12 nmol/L are considered borderline and may warrant measurement of sex hormone-binding globulin (SHBG) and calculation of free or bioavailable testosterone. Additional tests may include luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin to determine the underlying cause.

Urgent referral to endocrinology is indicated if you have very low testosterone (e.g., <5 nmol/L) with symptoms suggestive of pituitary disease (severe headaches, visual field defects, anosmia), markedly raised prolactin, or bilateral gynaecomastia, as these may indicate a pituitary tumour or other serious condition.

If hypogonadism is confirmed, your GP may initiate treatment or refer you to an endocrinologist. Before starting testosterone replacement therapy, discuss fertility; TRT suppresses sperm production and may cause infertility. If you wish to preserve or achieve fertility, specialist referral for alternative treatments (such as human chorionic gonadotrophin or selective oestrogen receptor modulators) may be appropriate.

Testosterone replacement therapy, when medically indicated, requires ongoing monitoring including:

• Baseline assessment: testosterone, haematocrit, PSA and digital rectal examination (as appropriate for age and risk), liver function tests, lipid profile

• Follow-up at 3–6 months: testosterone level (to guide dose adjustment), haematocrit, PSA, liver function, lipids

• Annual review thereafter: testosterone, haematocrit, PSA, liver function, lipids

• Bone density scans if indicated

Therapy should be paused or adjusted if haematocrit exceeds 54%, and underlying causes (such as sleep apnoea or smoking) should be evaluated. PSA monitoring follows age- and risk-appropriate guidelines.

Never self-diagnose or self-treat suspected low testosterone. Proper medical evaluation ensures appropriate treatment whilst monitoring for potential complications. If you have concerns about your testosterone levels or muscle-building goals, an honest conversation with your GP is the safest first step. If you experience any suspected side effects from testosterone therapy, report them via the MHRA Yellow Card Scheme at yellowcard.mhra.gov.uk.

Frequently Asked Questions