When a man with confirmed testosterone deficiency uses Testogel as prescribed, the treatment aims to restore testosterone levels to the mid-normal range, alleviating symptoms of hypogonadism. Testogel is a transdermal testosterone replacement therapy licensed in the UK for adult males with biochemically confirmed low testosterone. The gel delivers testosterone through the skin, bypassing liver metabolism and providing steady hormone levels over 24 hours. Proper use requires daily application, careful monitoring, and precautions to prevent transfer to others. Understanding what happens when a man takes Testogel—including expected benefits, potential risks, and monitoring requirements—is essential for safe and effective treatment.

What Is Testogel and How Does It Work?

Testogel is a transdermal testosterone replacement therapy (TRT) licensed in the UK for treating male hypogonadism—a condition where the testes produce insufficient testosterone. The gel contains testosterone as the active pharmaceutical ingredient, available in two formulations: Testogel 1% in 50 mg/5 g sachets and Testogel 16.2 mg/g as a metered-dose pump delivering approximately 20.25 mg per actuation.

The mechanism of action involves percutaneous absorption through the skin into the systemic circulation. Once applied to clean, dry skin (shoulders and upper arms for both formulations; abdomen also permitted for the 1% sachet formulation), testosterone is gradually absorbed over several hours, bypassing first-pass hepatic metabolism. This delivery method provides relatively stable testosterone levels over 24 hours.

Testosterone exerts its effects by binding to androgen receptors in target tissues throughout the body. These receptors are found in muscle, bone, the central nervous system, and reproductive tissues. Once bound, the testosterone-receptor complex influences gene transcription, leading to protein synthesis and the characteristic androgenic and anabolic effects. These include maintenance of muscle mass and strength, bone mineral density, libido, erectile function, mood regulation, and secondary sexual characteristics.

In the UK, Testogel is regulated by the Medicines and Healthcare products Regulatory Agency (MHRA) and is available only on prescription. The gel formulation offers convenience and steady-state testosterone levels when used consistently, though it requires daily application and careful attention to prevent transfer to others through skin contact.

Who Should Use Testogel in the UK?

Testogel is specifically indicated for testosterone replacement in adult males with hypogonadism confirmed through clinical symptoms and biochemical testing. According to the NICE Clinical Knowledge Summary, diagnosis requires both symptomatic presentation and consistently low serum testosterone levels measured on at least two separate occasions, preferably between 8:00 and 11:00 AM when testosterone levels are naturally highest.

Clinical indications for testosterone replacement include:

• Primary hypogonadism: Testicular failure due to genetic conditions (Klinefelter syndrome), chemotherapy, radiation, trauma, or orchitis

• Secondary hypogonadism: Hypothalamic or pituitary dysfunction affecting gonadotrophin secretion

• Age-related hypogonadism: Late-onset hypogonadism in older men with confirmed deficiency and troublesome symptoms

Symptoms warranting investigation typically include reduced libido, erectile dysfunction, decreased energy and motivation, mood disturbances, reduced muscle mass and strength, increased body fat, and decreased bone mineral density. However, these symptoms are non-specific and require biochemical confirmation.

Contraindications include known or suspected prostate cancer, male breast cancer, and hypersensitivity to any ingredients. Cautions and precautions apply to men with severe cardiac, renal or hepatic impairment, polycythaemia, untreated severe obstructive sleep apnoea, and those at high risk of cardiovascular disease. Women and children must not use Testogel due to virilisation risks.

Before initiating treatment, comprehensive assessment is essential, including digital rectal examination and prostate-specific antigen (PSA) testing (particularly in men over 50 or those with risk factors), full blood count, luteinising hormone (LH), follicle-stimulating hormone (FSH), sex hormone binding globulin (SHBG), prolactin, and cardiovascular risk evaluation. Endocrine referral should be considered for suspected secondary hypogonadism, elevated prolactin, or very low testosterone levels. The decision to prescribe should follow shared decision-making between clinician and patient, weighing potential benefits against risks.

What Happens When a Man Takes Testogel?

When a man with confirmed testosterone deficiency uses Testogel as prescribed, the treatment aims to restore testosterone levels to the mid-normal range for the local laboratory reference interval, thereby alleviating symptoms of hypogonadism. The therapeutic effects develop gradually rather than immediately, with different symptoms responding over varying timeframes.

Early responses (within 3–6 weeks) often include improvements in mood, energy levels, and sense of wellbeing. Many men report enhanced motivation and reduced feelings of depression or irritability. Libido typically begins to improve within this timeframe, though maximal effects on sexual function may take 3–6 months.

Intermediate effects (3–6 months) include changes in body composition. Testosterone promotes protein synthesis and muscle development whilst reducing fat mass, particularly visceral adipose tissue. Men may notice increased muscle strength and exercise capacity. Erectile function continues to improve during this period, though the response varies considerably between individuals and may depend on other contributing factors to erectile dysfunction.

Long-term benefits (6–12 months and beyond) include improvements in bone mineral density, which is particularly important for men with osteoporosis or osteopenia. Haematological changes occur, with haemoglobin and haematocrit levels typically increasing within the normal range. Some men may experience improvements in cognitive function, though evidence for this is mixed.

It is important to note that individual responses vary considerably. Some men experience dramatic symptom relief, whilst others notice more modest improvements. Factors influencing response include the severity of deficiency, age, concurrent medical conditions (particularly obesity, diabetes, and cardiovascular disease), and lifestyle factors. Realistic expectations should be established before commencing treatment, and men should understand that testosterone replacement addresses deficiency but is not a panacea for all age-related changes or lifestyle-related health issues.

Potential Side Effects and Risks for Men Using Testogel

Whilst Testogel is generally well-tolerated when appropriately prescribed and monitored, men should be aware of potential adverse effects ranging from minor local reactions to more significant systemic complications.

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

• Skin reactions: Erythema, acne, dry skin, or pruritus at application sites

• Prostate effects: Benign prostatic hyperplasia progression or elevated PSA levels

• Haematological changes: Increased haemoglobin and haematocrit (polycythaemia)

• Mood changes: Emotional lability, aggression, or anxiety in some individuals

• Gynaecomastia: Breast tissue enlargement due to peripheral aromatisation of testosterone to oestradiol

• Fluid retention/oedema: Particularly in those with cardiac, renal or hepatic impairment

Cardiovascular considerations remain an area of ongoing research. The MHRA and European Medicines Agency have reviewed the evidence and concluded it is not conclusive regarding increased cardiovascular risk with testosterone therapy. However, caution is advised in men with pre-existing cardiovascular disease or risk factors, and careful cardiovascular risk assessment is recommended before initiating treatment.

Polycythaemia (elevated red blood cell count) represents a significant risk, particularly in older men. Excessive haematocrit elevation (>0.54) increases blood viscosity and thrombotic risk, potentially necessitating dose reduction or treatment interruption. Regular monitoring through full blood counts is essential.

Fertility implications are crucial for men of reproductive age. Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis, reducing luteinising hormone and follicle-stimulating hormone secretion. This leads to decreased intratesticular testosterone and impaired spermatogenesis, potentially causing infertility. Men wishing to father children should discuss alternative treatments or fertility preservation before commencing Testogel.

Sleep apnoea may worsen with testosterone therapy, and men with symptoms such as loud snoring, witnessed apnoeas, or excessive daytime somnolence should undergo assessment before treatment initiation.

Suspected side effects should be reported through the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk or the Yellow Card app).

Safe Use and Monitoring Requirements

Proper application technique is fundamental to treatment efficacy and safety. Testogel should be applied once daily, preferably in the morning, to clean, dry, intact skin. Application sites vary by formulation:

• Testogel 1% sachets: Apply to shoulders, upper arms, or abdomen (not the genital area)

• Testogel 16.2 mg/g pump: Apply only to shoulders or upper arms

After application, men should:

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

• Wash hands thoroughly with soap and water immediately after application

• Cover the application site with clothing once dry

• Be aware the gel is flammable until dry; avoid fire, flames or smoking during application

• Rotate application sites to prevent skin irritation

• For Testogel 1% sachets: Avoid swimming or showering for at least 2 hours post-application

• For Testogel 16.2 mg/g pump: Avoid swimming or showering for at least 2 hours post-application

• Wash application sites thoroughly with soap and water before any situation involving close skin-to-skin contact with others

Transfer prevention is critical, as testosterone can be transmitted to partners or children through direct skin contact, potentially causing virilisation in women and children. If contact occurs, the exposed area should be washed immediately with soap and water. Partners and family members should be informed about these risks.

Monitoring protocols aligned with NICE Clinical Knowledge Summary guidance include:

• Baseline assessment: Testosterone levels (two morning samples), LH, FSH, SHBG, prolactin, PSA and prostate assessment (as appropriate for age/risk), full blood count, and cardiovascular risk evaluation

• 3-month review: Testosterone levels, full blood count, symptom assessment, and treatment response evaluation

• 6–12 month reviews: Repeat monitoring bloods and clinical assessment

• Annual monitoring: Comprehensive review including all baseline parameters

Dose adjustments may be necessary based on testosterone levels and clinical response. The goal is to maintain testosterone in the mid-normal range whilst minimising adverse effects. Some men may require dose increases if levels remain suboptimal, whilst others may need reductions if levels become supraphysiological or haematocrit rises excessively.

Lifestyle optimisation enhances treatment outcomes. Men should be encouraged to maintain healthy body weight, engage in regular exercise, ensure adequate sleep, moderate alcohol consumption, and cease smoking. These measures improve both testosterone levels and treatment response.

When to Seek Medical Advice About Testogel

Men using Testogel should be aware of situations requiring prompt medical consultation to ensure safe and effective treatment. Understanding these triggers helps prevent complications and optimises therapeutic outcomes.

Urgent medical attention (contact GP or NHS 111 immediately; call 999 for severe symptoms) is warranted for:

• Chest pain, breathlessness, or leg swelling: Potential indicators of cardiovascular events or venous thromboembolism

• Severe headaches or visual disturbances: These non-specific symptoms warrant assessment as they could indicate various conditions including polycythaemia-related complications

• Priapism: Painful erection lasting >4 hours requiring emergency treatment

• Signs of allergic reaction: Severe rash, facial swelling, or breathing difficulties

Routine medical review should be arranged if men experience:

• Inadequate symptom improvement: After 3–6 months of treatment, suggesting need for dose adjustment or investigation of other contributing factors

• Mood or behavioural changes: Increased aggression, irritability, anxiety, or depressive symptoms

• Urinary symptoms: Difficulty urinating, weak stream, or increased frequency suggesting prostate enlargement

• Breast changes: Enlargement, tenderness, or lumps requiring examination

• Skin reactions: Persistent or severe irritation at application sites

Partner or family concerns about testosterone transfer should prompt immediate discussion with healthcare providers. Signs of virilisation in female partners (acne, voice deepening, increased body hair) or children (premature puberty signs) require urgent assessment and treatment review. It is essential to reinforce proper application technique and transfer prevention measures.

Annual reviews are essential even when treatment appears successful. These appointments allow comprehensive reassessment of treatment necessity, monitoring for long-term complications, and adjustment of management strategies. Men should prepare for these consultations by noting any symptom changes, concerns, or questions.

Finally, men should never adjust doses independently or share medication with others. Testogel is prescribed based on individual biochemical and clinical assessment, and unsupervised use carries significant risks. Any concerns about treatment efficacy or tolerability should be discussed with prescribing clinicians rather than leading to self-directed dose modifications.

Frequently Asked Questions