Testogel is a widely prescribed testosterone replacement therapy in the UK, but does it work effectively in older men? As testosterone levels naturally decline with age, many older adults experience symptoms such as fatigue, reduced muscle strength, and diminished libido. Testogel, a transdermal gel delivering steady testosterone doses through the skin, aims to restore hormone levels and alleviate these symptoms. However, its effectiveness in older men depends on proper diagnosis of genuine hypogonadism, individualised risk assessment, and realistic expectations. This article examines the evidence for Testogel's efficacy in older adults, its benefits and limitations, and essential safety considerations.

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 characterised by abnormally low testosterone levels. In the UK, Testogel is available in two formulations: Testogel 50 mg/5 g gel (1%) supplied in sachets, and Testogel 16.2 mg/g gel supplied in a metered-dose pump. Both are clear, colourless gels applied once daily to clean, dry skin. The 1% formulation may be applied to the shoulders, upper arms, or abdomen, whereas the 16.2 mg/g pump formulation is applied only to the shoulders and upper arms. The gel is designed to deliver a steady, physiological dose of testosterone through the skin and into the bloodstream.

Once applied, the alcohol-based gel dries within minutes, allowing testosterone to be absorbed gradually over 24 hours. This transdermal delivery system provides more stable serum testosterone levels than some other formulations, such as intramuscular injections, which can cause peaks and troughs in hormone levels. The absorbed testosterone is then converted in peripheral tissues to its active metabolites, including dihydrotestosterone (DHT) and oestradiol, which mediate many of testosterone's physiological effects.

Mechanism of action involves testosterone binding to androgen receptors in various tissues, influencing protein synthesis, muscle mass, bone density, libido, mood, and cognitive function. In older men, age-related decline in testosterone—sometimes termed late-onset hypogonadism—can contribute to symptoms such as fatigue, reduced muscle strength, decreased libido, and mood disturbances. Testogel aims to restore testosterone levels to the normal physiological range, thereby alleviating these symptoms.

Important safety advice: Patients must wash their hands thoroughly after application and cover the treated area with clothing once the gel has dried. Women and children must avoid contact with the application site. Patients should wait at least six hours before washing or swimming, and should wash the application site with soap and water before any anticipated close skin-to-skin contact with others.

Testogel is a prescription-only medicine in the UK, regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). It should only be initiated following comprehensive clinical and biochemical assessment to confirm genuine hypogonadism, rather than normal age-related decline alone. The gel must not be applied to the genital area.

References: Testogel 50 mg/5 g and 16.2 mg/g SmPCs (emc); NHS: Hypogonadism; MHRA.

Benefits and Limitations of Testogel for Older Adults

Clinical benefits of Testogel in older men with confirmed symptomatic hypogonadism can be meaningful, though responses vary. Evidence from trials such as the Testosterone Trials (TTrials) and the TRAVERSE cardiovascular safety study suggests that testosterone replacement may improve:

• Muscle mass and strength: Studies demonstrate modest increases in lean body mass and grip strength, which may help reduce frailty, though effects on fall risk are not definitively proven.

• Bone mineral density: Testosterone therapy can enhance bone density over 6–12 months or longer, though robust evidence for fracture risk reduction is lacking.

• Sexual function: Many men report improvements in libido within weeks to months; erectile function may also improve, though men with erectile dysfunction may still require phosphodiesterase-5 (PDE5) inhibitors.

• Mood and quality of life: Some patients experience enhanced energy levels and reduced depressive symptoms within weeks, though effects are variable and multifactorial.

• Metabolic parameters: There is emerging evidence that TRT may favourably influence body composition and insulin sensitivity in selected patients, though results are mixed and patient selection is important.

However, important limitations must be recognised. The benefits of testosterone therapy in older men remain an area of ongoing research, and not all patients respond equally. NICE guidance (NICE CKS: Hypogonadism in males) emphasises that TRT should only be offered when hypogonadism is confirmed by consistently low testosterone levels (typically measured on two separate occasions in the morning, at least one week apart) alongside relevant symptoms. Age-related testosterone decline without symptoms does not warrant treatment.

Limitations include:

• Variable symptom improvement: Not all men experience significant benefit, particularly if symptoms are multifactorial or unrelated to testosterone deficiency.

• Cardiovascular considerations: While recent large trials (TRAVERSE, 2023) have been reassuring regarding cardiovascular safety, individualised risk assessment remains essential, particularly in men with pre-existing cardiovascular disease.

• Potential adverse effects: These include skin reactions at application sites, polycythaemia (increased red blood cell count), benign prostatic enlargement, and mood changes.

• Transfer risk: Gel can transfer to partners or children through skin contact, necessitating careful hygiene measures and covering of treated skin.

Testogel is not a panacea for ageing and should form part of a holistic approach including lifestyle modification, management of comorbidities, and realistic patient expectations. Typical timelines for benefit include improvements in libido and energy within weeks, with effects on bone density and body composition emerging over 6–12 months.

References: NICE CKS: Hypogonadism in males; Society for Endocrinology UK position statement (2022); BSSM guideline on adult testosterone deficiency; TTrials (NEJM 2016–2017); TRAVERSE trial (NEJM 2023).

Who Should Not Use Testogel?

Absolute contraindications to Testogel use, as per the Summary of Product Characteristics (SmPC), include:

• Known or suspected prostate cancer or male breast cancer: Testosterone can stimulate growth of hormone-sensitive tumours.

• Hypersensitivity: Known allergy to testosterone or any gel excipients.

• Use in women and children: Testogel is not licensed for use in women or children and must not be used in these populations.

Cautions and conditions requiring careful assessment include:

• Suspected prostate cancer: Men with elevated prostate-specific antigen (PSA) or abnormal digital rectal examination (DRE) findings require further investigation before TRT initiation.

• Severe heart failure or significant cardiac disease: Testosterone may worsen fluid retention. The SmPC advises caution and discontinuation if oedema with or without congestive heart failure develops. Men with recent myocardial infarction, stroke, or unstable angina warrant cautious evaluation and shared decision-making.

• Polycythaemia: Pre-existing elevated haematocrit (typically >54%) requires investigation and normalisation before starting TRT. Treatment should be withheld or stopped if polycythaemia develops.

• Obstructive sleep apnoea: Testosterone may exacerbate this condition; assessment or treatment should precede TRT.

• Benign prostatic hyperplasia (BPH): Men with significant lower urinary tract symptoms require careful monitoring, as testosterone may worsen urinary obstruction.

• Liver or kidney impairment: Use with caution and monitor closely; the SmPC advises vigilance rather than specific dose adjustment.

• Epilepsy or migraine: Testosterone may influence seizure threshold or headache frequency in susceptible individuals; use with caution.

Special populations requiring particular consideration include:

• Men wishing to preserve fertility: Exogenous testosterone suppresses gonadotrophin (LH and FSH) secretion, reducing spermatogenesis. Alternative treatments or referral to a fertility specialist should be discussed.

• Older men with multiple comorbidities: Polypharmacy and frailty necessitate individualised risk-benefit assessment and may warrant endocrinology referral.

Baseline assessment before prescribing Testogel should include:

• Thorough history-taking and physical examination (including prostate assessment via DRE in men over 50 or with urinary symptoms)

• Morning serum testosterone on two separate occasions (at least one week apart)

• Luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin to distinguish primary from secondary hypogonadism and exclude pituitary disease

• Full blood count (haemoglobin and haematocrit)

• Prostate-specific antigen (PSA)

• Liver function tests

• Lipid profile and HbA1c (if diabetic or at metabolic risk)

• Consider pituitary imaging if secondary hypogonadism is suspected

Shared decision-making and informed consent are essential components of safe prescribing. Patients should be counselled on the need for ongoing monitoring and the importance of preventing gel transfer to others.

References: Testogel SmPCs (emc); NICE CKS: Hypogonadism in males; Society for Endocrinology UK/BSSM guidance.

Monitoring and Safety Considerations for Older Men

Regular monitoring is crucial to ensure efficacy and detect adverse effects early. UK guidance from NICE, the Society for Endocrinology, and the British Society for Sexual Medicine (BSSM) recommend the following surveillance schedule:

Baseline assessments (before initiating Testogel):

• Morning serum testosterone (on two separate occasions, at least one week apart)

• Luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin

• Full blood count (haemoglobin and haematocrit)

• Prostate-specific antigen (PSA)

• Liver function tests

• Lipid profile and HbA1c (if diabetic or at metabolic risk)

• Digital rectal examination (DRE) in men over 50 or with urinary symptoms

Follow-up monitoring:

• At 3 months: Testosterone levels (to assess dose adequacy), full blood count (haematocrit), PSA, and symptom review.

• At 6–12 months: Repeat testosterone, haematocrit, PSA, and clinical assessment including DRE as clinically indicated.

• Annually thereafter: Testosterone, full blood count (haematocrit), PSA, and prostate examination as clinically indicated. Lipid profile and liver function tests may be repeated based on individual risk factors and clinical judgement.

Dosing and titration: Testogel is typically started at a standard dose (e.g., 50 mg daily for the 1% formulation; 40.5 mg daily for the 16.2 mg/g pump). Dose adjustments are made based on serum testosterone levels and clinical response, within the licensed dose range. Patients should follow product-specific instructions provided with their formulation.

Key safety considerations for older men include:

• Polycythaemia: Testosterone stimulates erythropoiesis. Haematocrit >54% warrants dose reduction or temporary cessation. Persistent elevation may require investigation, venesection, or discontinuation.

• Prostate monitoring: Annual PSA and clinical assessment (including DRE where appropriate) are essential. Refer urgently to urology per NICE NG12 (Suspected cancer: recognition and referral) if PSA is age-inappropriately elevated, DRE is abnormal, or there is clinical concern. Use age-specific PSA reference ranges to guide referral decisions.

• Cardiovascular vigilance: Monitor blood pressure, lipids, and symptoms of angina, heart failure, or thromboembolic events. Encourage lifestyle modification and manage cardiovascular risk factors.

• Skin reactions: Application site irritation is common. Rotating sites and ensuring skin is dry before application can help.

• Transfer prevention: Patients must wash hands thoroughly after application, cover treated areas with clothing once the gel has dried, and avoid skin-to-skin contact with others (especially women and children) until the gel has dried completely. Wait at least six hours before washing or swimming. Wash the application site with soap and water before any anticipated close contact.

When to contact a GP:

• New or worsening urinary symptoms

• Chest pain, breathlessness, or leg swelling

• Persistent headaches or visual disturbances

• Mood changes, aggression, or sleep disturbance

• Skin reactions or allergic symptoms

Reporting suspected side effects: Patients and healthcare professionals are encouraged to report any suspected adverse reactions via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or by searching for MHRA Yellow Card in the Google Play or Apple App Store.

Patients should be counselled that benefits may take several weeks to months to manifest, and that TRT is typically a long-term commitment requiring ongoing medical supervision. Discontinuation should be considered if no symptomatic benefit is evident after six months of adequate dosing, or if significant adverse effects occur. Consider referral to endocrinology for complex cases or if secondary hypogonadism is suspected.

References: Testogel SmPCs (emc); NICE CKS: Hypogonadism in males; NICE NG12: Suspected cancer – recognition and referral; Society for Endocrinology UK position statement (2022); BSSM guideline; MHRA Yellow Card scheme.

Frequently Asked Questions