When using Testogel for testosterone replacement therapy, regular blood tests are essential to ensure treatment is both safe and effective. UK clinical guidelines recommend checking testosterone levels approximately 3 months after starting treatment or adjusting your dose, then every 6–12 months once stable levels are achieved. Additional monitoring includes full blood count, prostate-specific antigen (PSA), and clinical assessments to detect potential side effects such as elevated red blood cell count or prostate changes. Your prescribing clinician will tailor the monitoring schedule to your individual circumstances, age, and health status. This article explains the recommended testing frequency, what happens during monitoring appointments, and when dose adjustments may be needed.

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. Available as a clear or slightly opalescent gel, it contains testosterone as the active ingredient and is applied once daily to clean, dry skin.

The most commonly prescribed formulation in the UK is Testogel 16.2 mg/g gel in a metered-dose pump. According to the UK Summary of Product Characteristics (SmPC), this formulation should be applied to the shoulders and upper arms only—not to the abdomen or genital area. Once applied, the gel dries within a few minutes and testosterone is absorbed through the skin into the bloodstream over several hours. This delivery method provides a steady release of hormone throughout the day. The pump formulation allows for dose adjustments in increments, typically ranging from 20.25 mg to 81 mg daily, depending on individual response and blood test results.

Mechanism of action: Testosterone is an androgen hormone essential for maintaining male sexual characteristics, muscle mass, bone density, mood regulation, and metabolic function. In hypogonadism, endogenous production falls below the normal laboratory reference range, leading to symptoms such as reduced libido, erectile dysfunction, fatigue, loss of muscle mass, and mood disturbances. Testogel supplements circulating testosterone, restoring levels to within the normal adult male range with the aim of alleviating these symptoms.

Important safety information: Testogel is a prescription-only medicine regulated by the MHRA. Treatment should only be initiated and supervised by healthcare professionals experienced in managing testosterone deficiency, following confirmation of hypogonadism through appropriate biochemical testing and clinical assessment. Testogel is contraindicated in men with known or suspected prostate cancer or male breast cancer. To prevent accidental transfer to others, wash your hands thoroughly with soap and water immediately after applying the gel, allow the gel to dry completely before dressing, cover the application site with clothing, and avoid skin-to-skin contact with others until the gel has dried. Follow the SmPC guidance on bathing and swimming after application. If you suspect you or someone else has experienced a side effect, you can report it via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk or through the Yellow Card app.

How Often Should Testosterone Levels Be Checked on Testogel?

Regular monitoring of testosterone levels is essential when using Testogel to ensure treatment efficacy and safety. UK clinical practice, informed by NICE Clinical Knowledge Summaries (CKS), the British Society for Sexual Medicine (BSSM), and the Society for Endocrinology, recommends a structured monitoring schedule that varies depending on the treatment phase.

Initial monitoring phase: When starting Testogel or after any dose adjustment, testosterone levels should be checked approximately 3 months after initiation or change. This allows sufficient time for steady-state hormone levels to be achieved and for clinical response to be assessed. Blood samples should be taken according to the timing specified in the Testogel SmPC—typically as a pre-dose (trough) level in the morning before the next application.

Maintenance monitoring: Once a stable, effective dose has been established and testosterone levels are within the target range (the local laboratory adult male reference range, with symptom improvement), monitoring frequency can be reduced. UK guidelines recommend checking testosterone levels every 6–12 months during stable treatment. However, individual circumstances may necessitate more frequent testing—for example, in older men, those with cardiovascular risk factors, or if symptoms suggest under- or over-replacement.

Additional monitoring parameters: Beyond testosterone levels, comprehensive TRT monitoring includes:

• Full blood count (haematocrit and haemoglobin) at 3 months, then at 12 months, and annually thereafter, as testosterone can stimulate red blood cell production. If haematocrit rises above 0.54, treatment should be interrupted or the dose reduced, and the cause investigated; venesection may be considered.

• Prostate-specific antigen (PSA) at baseline, 3–6 months, 12 months, and then annually in men over 40 or those at higher prostate cancer risk. Digital rectal examination (DRE) should be performed if clinically indicated. Refer urgently under NICE NG12 if PSA is age-specifically elevated or DRE is abnormal.

• Liver function tests and lipid profile if clinically indicated, based on individual risk factors.

Your prescribing clinician will determine the most appropriate monitoring schedule based on your individual clinical situation, age, comorbidities, and treatment response.

What Happens During Testosterone Monitoring Appointments?

Testosterone monitoring appointments serve multiple purposes beyond simply checking hormone levels. These consultations provide an opportunity for comprehensive assessment of treatment efficacy, safety, and overall health.

Blood testing: The cornerstone of monitoring is venous blood sampling to measure serum testosterone levels. For men using Testogel, blood should be drawn at the time specified in the product SmPC—typically as a pre-dose (trough) level before the next application. The sample measures total testosterone and sometimes includes sex hormone-binding globulin (SHBG) to calculate free or bioavailable testosterone—the metabolically active fraction. If response is suboptimal or secondary hypogonadism is suspected, luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin may also be checked. Additional blood tests assess haematocrit (red blood cell concentration), haemoglobin, and—if clinically indicated—liver function, lipids, and PSA.

Clinical assessment: Your healthcare provider will conduct a structured review including:

• Symptom evaluation: Discussion of libido, erectile function, energy levels, mood, sleep quality, and physical performance

• Physical examination: Assessment of secondary sexual characteristics, muscle mass, body composition, and gynaecomastia (breast tissue development). If gynaecomastia is symptomatic, oestradiol levels may be checked and application practices reviewed.

• Cardiovascular review: Blood pressure measurement and assessment of cardiovascular risk factors

• Prostate assessment: In appropriate age groups, digital rectal examination may be performed if clinically indicated

Treatment review and safety counselling: The appointment provides an opportunity to discuss:

• Adherence to daily application and correct technique

• Skin reactions at application sites

• Any adverse effects experienced

• Transfer-prevention measures: Ensuring you wash your hands after applying the gel, allow it to dry completely, cover the application site with clothing, and avoid skin-to-skin contact with others (especially women and children) until the gel has dried. Confirm you are following bathing and swimming guidance per the SmPC.

• Lifestyle factors affecting treatment (exercise, diet, alcohol, smoking)

• New or worsening lower urinary tract symptoms, which warrant prompt GP review

Based on these findings, your clinician may adjust the Testogel dose, modify the monitoring schedule, or address any emerging safety concerns. This holistic approach ensures TRT remains both effective and safe throughout long-term treatment.

Signs Your Testogel Dose May Need Adjusting

Recognising when your Testogel dose may be inadequate or excessive is important for optimising treatment outcomes. Both under-replacement and over-replacement can cause problematic symptoms.

Signs of under-replacement (dose too low):

• Persistent or returning symptoms of hypogonadism: low libido, erectile dysfunction, fatigue, reduced motivation

• Continued loss of muscle mass or difficulty building muscle despite exercise

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

• Reduced sense of wellbeing despite treatment

• Blood test results showing testosterone levels below the local laboratory adult male reference range

If you experience these symptoms despite regular Testogel use, contact your prescribing clinician. Dose adjustments are typically made in increments, with reassessment after 3 months.

Signs of over-replacement (dose too high):

• Polycythaemia symptoms: Headaches, dizziness, visual disturbances, or flushing may indicate elevated red blood cell count. If your haematocrit rises above 0.54, your clinician will interrupt or reduce your dose and investigate the cause; venesection may be considered.

• Excessive aggression, irritability, or mood swings

• Acne or oily skin (particularly if new or worsening)

• Fluid retention or ankle swelling

• Sleep disturbances or sleep apnoea symptoms (snoring, daytime sleepiness)

• Gynaecomastia (breast tissue enlargement or tenderness)

When to seek urgent medical advice:

Contact your GP or seek immediate medical attention if you experience:

• Chest pain, shortness of breath, or signs of blood clots (leg pain, swelling, warmth)

• Prolonged, painful erections (priapism)—this is uncommon but requires prompt medical review

• Severe mood changes or suicidal thoughts

• Jaundice (yellowing of skin or eyes)

• Difficulty urinating, acute urinary retention, or new/worsening lower urinary tract symptoms

Never adjust your Testogel dose independently. All dose modifications should be made under medical supervision following appropriate blood testing and clinical assessment. Maintaining open communication with your healthcare team ensures treatment remains tailored to your individual needs whilst minimising potential risks.

NHS Guidelines for Testosterone Replacement Therapy Monitoring

The NHS follows evidence-based guidelines for testosterone replacement therapy monitoring, primarily informed by NICE Clinical Knowledge Summaries (CKS), the British Society for Sexual Medicine (BSSM), the Society for Endocrinology, and NICE NG12 for suspected cancer referral.

Pre-treatment requirements:

Before initiating Testogel, NHS protocols require:

• Confirmation of hypogonadism through two separate early-morning testosterone measurements showing levels below the local laboratory adult male reference range. Values between 8–12 nmol/L are considered borderline and require careful clinical correlation with symptoms.

• Clinical symptoms consistent with testosterone deficiency

• Baseline measurement of luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin to distinguish primary from secondary hypogonadism and to guide further pituitary evaluation if needed. If red flags are present (e.g., visual symptoms, severe headaches, very low LH/FSH with hyperprolactinaemia), urgent referral for pituitary imaging may be required.

• Exclusion of secondary causes (pituitary disorders, medications, obesity)

• Baseline investigations including full blood count, PSA (in men over 40), and—if clinically indicated—liver function and lipid profile

• Prostate assessment (PSA and, if indicated, digital rectal examination) in appropriate age groups

Structured monitoring schedule:

UK guidelines recommend:

• 3 months: First review with testosterone level, full blood count (haematocrit and haemoglobin), clinical assessment, and dose optimisation. If haematocrit is >0.54, interrupt or reduce treatment and investigate.

• 6 months: Follow-up testosterone level and symptom review

• 12 months: Comprehensive review including testosterone, full blood count, PSA, and—if clinically indicated—liver function, lipids, and cardiovascular risk assessment

• Annually thereafter: Ongoing monitoring with testosterone levels, haematocrit, PSA (with DRE if indicated), and clinical review

PSA monitoring and referral: PSA should be checked at baseline, 3–6 months, 12 months, and then annually. Refer urgently under NICE NG12 if PSA is age-specifically elevated, DRE is abnormal, or there is a significant PSA rise during treatment.

Special considerations:

More intensive monitoring may be required for:

• Men over 60 years

• Those with cardiovascular disease or risk factors

• Patients with elevated haematocrit (>0.54)

• Men with borderline PSA or prostate concerns

• Those with sleep apnoea, liver disease, or obesity

Fertility considerations: Exogenous testosterone suppresses spermatogenesis (sperm production). If you are planning to father children, discuss this with your clinician before starting treatment, as alternative therapies may be more appropriate.

Shared care arrangements:

Many NHS areas operate shared care protocols between specialist endocrinology or urology services and general practice. Typically, specialists initiate treatment and stabilise dosing, then transfer ongoing monitoring to GPs with specialist support available for complex cases.

Patient responsibilities:

NHS guidance emphasises patient engagement in monitoring, including attending scheduled appointments, reporting symptoms promptly, and understanding the importance of long-term surveillance. Treatment continuation requires ongoing clinical need and absence of contraindications.

These structured NHS protocols ensure Testogel therapy remains evidence-based, safe, and effective throughout the duration of treatment, with regular opportunities to reassess clinical benefit and minimise potential adverse effects.

Frequently Asked Questions