Testogel (testosterone gel) is a widely prescribed testosterone replacement therapy in the UK, but concerns about its cardiovascular effects, particularly on blood pressure, are important for patients and clinicians. Whilst testosterone therapy can offer significant benefits for men with confirmed hypogonadism, understanding the potential impact on blood pressure is essential for safe prescribing and monitoring. The relationship between Testogel and hypertension is complex, with individual responses varying considerably based on baseline health, dosage, and concurrent medical conditions. This article examines the evidence linking Testogel to blood pressure changes, explores the underlying mechanisms, identifies at-risk patient groups, and provides guidance on appropriate monitoring and when to seek medical advice.

Can Testogel Cause High Blood Pressure?

Testogel (testosterone gel) may contribute to elevated blood pressure in some individuals. The Testogel Summary of Product Characteristics (SmPC) specifically states that androgens may increase blood pressure and advises caution in patients with hypertension.

Testosterone replacement therapy (TRT), including topical preparations like Testogel, has been associated with modest increases in blood pressure in certain patient populations. While the relationship between testosterone therapy and hypertension is complex, the Medicines and Healthcare products Regulatory Agency (MHRA) acknowledges cardiovascular risks associated with testosterone products. Clinical studies have shown variable results, with some patients experiencing blood pressure changes while others show no significant effects.

The mechanism by which testosterone might affect blood pressure involves multiple pathways, including fluid retention, increased red blood cell production (erythrocytosis), and effects on vascular tone. Individual responses vary considerably depending on baseline cardiovascular health, dosage, treatment duration, and concurrent medical conditions. Men with pre-existing hypertension, cardiovascular disease, or metabolic syndrome may be more susceptible to blood pressure changes during TRT.

It is important to note that untreated testosterone deficiency (hypogonadism) itself has been associated with increased cardiovascular risk factors, including hypertension. Therefore, the decision to initiate or continue Testogel therapy requires careful assessment of individual risk-benefit profiles. In the UK, treatment is typically initiated by specialists (endocrinologists or urologists), with ongoing management often shared between specialists and GPs under local protocols, with appropriate cardiovascular monitoring throughout treatment.

How Testosterone Replacement Therapy Affects Blood Pressure

Testosterone exerts multiple physiological effects that can influence blood pressure regulation through both direct and indirect mechanisms. Understanding these pathways helps explain why some individuals experience blood pressure changes during TRT whilst others do not.

Fluid and Sodium Retention

Testosterone can promote sodium and water retention by affecting renal handling of electrolytes and stimulating the renin-angiotensin-aldosterone system (RAAS). This increased fluid volume expands plasma volume, potentially raising blood pressure, particularly in individuals with compromised renal function or pre-existing fluid balance issues. The Testogel SmPC specifically warns about the risk of oedema, with or without congestive heart failure, particularly in patients with pre-existing cardiac, renal or hepatic disease.

Erythrocytosis and Blood Viscosity

One of the most consistent effects of testosterone therapy is stimulation of erythropoiesis (red blood cell production) in the bone marrow. Elevated haematocrit levels increase blood viscosity, which can raise peripheral vascular resistance and consequently blood pressure. The Testogel SmPC requires regular full blood count monitoring. Clinical guidelines from the British Society for Sexual Medicine (BSSM) and Endocrine Society recommend that haematocrit levels above 0.54 (54%) warrant dose reduction or treatment interruption.

Vascular Effects

Testosterone influences vascular smooth muscle tone and endothelial function through complex mechanisms. Whilst some studies suggest testosterone may have vasodilatory properties that could lower blood pressure, chronic supraphysiological levels or rapid normalisation in previously deficient men may alter vascular reactivity. The net effect on blood pressure depends on the balance between these competing influences and individual vascular responsiveness.

Metabolic Changes

TRT can favourably affect body composition by reducing fat mass and increasing lean muscle mass, potentially improving insulin sensitivity. These metabolic improvements might indirectly benefit blood pressure control in some patients, particularly those with metabolic syndrome. However, weight gain from increased muscle mass or fluid retention may counteract these benefits in others.

Testosterone therapy may also worsen or unmask obstructive sleep apnoea, which can contribute to elevated blood pressure.

Risk Factors and Who May Be More Susceptible

Certain patient groups face elevated risk of developing or experiencing worsening hypertension during Testogel therapy. Identifying these risk factors enables clinicians to implement appropriate monitoring strategies and make informed treatment decisions.

Pre-existing Cardiovascular Conditions

Men with established hypertension, coronary artery disease, heart failure, or previous stroke require particularly careful assessment before initiating TRT. The European Medicines Agency (EMA) has reviewed the cardiovascular risks of testosterone products and advises caution when prescribing to patients with cardiovascular disease. The Testogel SmPC specifically highlights the need for caution in patients with hypertension. Baseline blood pressure control should ideally be optimised before starting Testogel, and more frequent monitoring is warranted throughout treatment.

Age and Comorbidities

Older men (typically over 65 years) often have reduced vascular compliance and multiple cardiovascular risk factors, making them more susceptible to blood pressure changes. Concurrent conditions such as type 2 diabetes, chronic kidney disease, obesity, and obstructive sleep apnoea further increase vulnerability. The presence of metabolic syndrome—characterised by central obesity, dyslipidaemia, insulin resistance, and hypertension—represents a particularly high-risk profile.

The Testogel SmPC specifically advises caution in patients with severe cardiac, hepatic or renal insufficiency due to the increased risk of fluid retention and oedema.

Dosage and Formulation Factors

Higher testosterone doses and supraphysiological serum levels increase the likelihood of adverse cardiovascular effects, including blood pressure elevation. Topical preparations like Testogel typically produce more stable testosterone levels compared to intramuscular injections. However, improper application technique or excessive dosing can lead to unpredictable absorption and higher peak levels.

Genetic and Individual Variability

Genetic polymorphisms affecting androgen receptor sensitivity, drug metabolism, and cardiovascular regulation contribute to individual variation in response to TRT. Some men may be inherently more susceptible to testosterone-related blood pressure changes due to their unique genetic and physiological makeup. Family history of early cardiovascular disease or hypertension may indicate increased susceptibility, though this remains an area requiring further research.

Monitoring Blood Pressure While Using Testogel

Systematic cardiovascular monitoring forms an essential component of safe testosterone replacement therapy. NICE Clinical Knowledge Summary (CKS) on male hypogonadism emphasises the importance of regular assessment of cardiovascular risk factors, including blood pressure, throughout TRT.

Baseline Assessment

Before initiating Testogel, comprehensive cardiovascular evaluation should include:

• Blood pressure measurement using validated equipment and proper technique (seated, rested, multiple readings)

• Full blood count to establish baseline haematocrit

• Lipid profile and fasting glucose or HbA1c

• Assessment of cardiovascular symptoms and risk factors

• Consideration of ECG if clinically indicated (based on symptoms or cardiovascular history)

This baseline data provides reference points for detecting treatment-related changes and helps stratify individual cardiovascular risk.

Ongoing Monitoring Schedule

The British Society for Sexual Medicine recommends monitoring at 3, 6, and 12 months after starting TRT, then annually if stable. Blood pressure should be checked at each monitoring visit, with more frequent assessment if readings are elevated or borderline. According to NICE guideline NG136, hypertension is diagnosed when clinic blood pressure is ≥140/90 mmHg, confirmed by ambulatory or home blood pressure monitoring (≥135/85 mmHg).

Home blood pressure monitoring may provide additional valuable data, particularly for detecting white-coat hypertension or masked hypertension. NICE recommends taking readings at consistent times, ideally morning and evening, after resting for five minutes.

Full blood count monitoring is crucial, as elevated haematocrit often precedes or accompanies blood pressure changes. According to BSSM and Endocrine Society guidelines, haematocrit should be checked at 3-4 months initially, then 6-12 monthly. If haematocrit exceeds 0.54, dose reduction or temporary discontinuation is recommended until levels normalise.

Interpreting Blood Pressure Changes

Small increases in blood pressure may not require intervention if readings remain within normal range (below 140/90 mmHg in clinic). However, any sustained elevation above 140/90 mmHg warrants clinical review and consideration of antihypertensive therapy or TRT modification. The decision to continue, adjust, or discontinue Testogel should be individualised, weighing symptomatic benefits against cardiovascular risks.

When to Seek Medical Advice About Blood Pressure Changes

Patients using Testogel should be educated about warning signs that warrant prompt medical attention, as well as circumstances requiring routine clinical review.

Urgent Medical Attention Required

Seek immediate medical help (call 999 or attend A&E) if you experience:

• Severe headache with visual disturbance, confusion, or altered consciousness

• Chest pain, pressure, or tightness, particularly with exertion

• Sudden severe breathlessness or difficulty breathing

• Weakness, numbness, or speech difficulties (potential stroke symptoms)

These symptoms may indicate hypertensive emergency or acute cardiovascular events requiring urgent assessment, though they are rare complications of TRT.

Contact NHS 111 or Your GP Promptly

Arrange a GP appointment or contact NHS 111 if you notice:

• Persistent headaches, particularly in the morning

• Unexplained dizziness or light-headedness

• Visual changes or blurred vision

• Chest discomfort or palpitations

• Unusual fatigue or reduced exercise tolerance

• Facial flushing or feeling unusually warm

• Ankle swelling or rapid weight gain (suggesting fluid retention)

These symptoms may indicate elevated blood pressure or other cardiovascular changes requiring assessment and possible treatment adjustment.

Routine Monitoring Situations

Contact your prescribing specialist or GP for routine review if:

• Home blood pressure readings consistently exceed 135/85 mmHg

• You have missed scheduled monitoring appointments

• You are concerned about any aspect of your Testogel therapy

• You develop new medical conditions or start new medications

Self-Monitoring Guidance

If you monitor blood pressure at home, keep a written record of readings with dates and times. Take readings at consistent times, ideally morning and evening, after resting for five minutes. Share these records with your healthcare team at monitoring appointments. Remember that single elevated readings are common and not necessarily concerning—it is the pattern over time that matters. Never adjust or stop Testogel without medical guidance, as abrupt discontinuation can cause symptom recurrence and hormonal fluctuation.

If you experience any side effects that you think may be related to Testogel, report them to the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk), which helps monitor the safety of medicines.

Frequently Asked Questions