Many men wonder whether tadalafil, a commonly prescribed treatment for erectile dysfunction, can increase testosterone levels. This question often arises because sexual health concerns frequently overlap, with some men experiencing both erectile difficulties and symptoms of low testosterone. Understanding the distinction between these conditions is essential for appropriate treatment. Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor that works by enhancing blood flow to facilitate erections, but it does not influence testosterone production. This article examines the evidence surrounding tadalafil's effects on hormone levels, the relationship between erectile function and testosterone, and appropriate treatment options available through the NHS.

Does Tadalafil Increase Testosterone Levels?

Tadalafil does not increase testosterone levels. This phosphodiesterase type 5 (PDE5) inhibitor works by enhancing blood flow to the penis, facilitating erectile function in men with erectile dysfunction (ED). Its mechanism of action involves inhibiting the enzyme PDE5, which breaks down cyclic guanosine monophosphate (cGMP) in smooth muscle cells. By preventing this breakdown, tadalafil allows blood vessels to remain dilated, improving erectile response to sexual stimulation.

The confusion surrounding tadalafil and testosterone often stems from the interconnected nature of sexual health concerns. Many men experiencing erectile dysfunction may also have low testosterone (hypogonadism), leading to questions about whether treating one condition affects the other. However, tadalafil is not licensed or evidenced to increase testosterone; its Summary of Product Characteristics (SmPC) does not list effects on testosterone levels. The drug does not interact with the hypothalamic-pituitary-gonadal axis, which regulates testosterone synthesis in the testes.

Some men report improved sexual confidence and performance whilst taking tadalafil, which may indirectly influence their perception of vitality and wellbeing. However, these subjective improvements should not be confused with actual hormonal changes. If you are experiencing symptoms of low testosterone—such as reduced libido, fatigue, mood changes, or loss of muscle mass—alongside erectile difficulties, it is essential to consult your GP for appropriate investigation. Blood tests measuring total testosterone levels, typically taken in the morning (7-11am) when levels peak, are the initial assessment. If total testosterone is borderline or if sex hormone binding globulin (SHBG) is abnormal, calculated free testosterone may be assessed.

Importantly, tadalafil is contraindicated in patients taking nitrates or riociguat due to potentially dangerous drops in blood pressure. Men with significant cardiovascular disease may require assessment before starting treatment.

The Relationship Between Erectile Function and Testosterone

Erectile function and testosterone levels are interconnected but distinct aspects of male sexual health. Testosterone plays a crucial role in maintaining libido (sexual desire), but its direct effect on erectile mechanics is more nuanced. The hormone influences nitric oxide production in penile tissue, supports the health of endothelial cells lining blood vessels, and maintains the structural integrity of erectile tissue. However, many men with low testosterone can still achieve erections, particularly in response to direct physical stimulation.

Research indicates that a substantial minority (around 20-40%) of men with erectile dysfunction have concurrent low testosterone levels. This overlap creates a complex clinical picture where both conditions may contribute to sexual difficulties. Men with hypogonadism often report reduced spontaneous erections (such as morning erections) and diminished sexual thoughts, even when their ability to achieve erections during sexual activity remains relatively preserved. Conversely, men with normal testosterone levels may experience significant erectile dysfunction due to vascular, neurological, or psychological factors.

The distinction between desire and performance is clinically important. Tadalafil addresses the mechanical aspects of achieving and maintaining an erection by improving blood flow, but it does not restore sexual desire in men whose primary issue is low testosterone. According to NICE guidance, men presenting with erectile dysfunction should be assessed for underlying causes, including hormonal deficiencies. A comprehensive evaluation includes medical history, physical examination, and appropriate blood tests to measure testosterone, glucose (HbA1c or fasting glucose), lipid profile, blood pressure, and in some cases luteinising hormone (LH), follicle-stimulating hormone (FSH), and prolactin.

Urgent referral to endocrinology is warranted for very low testosterone with low/normal LH/FSH, hyperprolactinaemia, or visual symptoms/headaches. Urology referral may be appropriate for abnormal prostate-specific antigen (PSA) or digital rectal examination (DRE), while cardiology assessment should be considered if erectile dysfunction occurs with exertional chest pain. This approach ensures that both vascular and hormonal contributors to sexual dysfunction are identified and addressed appropriately.

What Research Shows About Tadalafil and Hormone Levels

Studies examining tadalafil's effects on hormone levels have demonstrated that the medication does not significantly alter testosterone concentrations in most men. Most studies (often small) show no clinically meaningful or consistent change in testosterone with tadalafil; it is not a testosterone-raising therapy. These findings confirm that tadalafil's therapeutic effects are mediated through vascular mechanisms rather than hormonal pathways.

Some smaller studies have reported modest increases in testosterone levels among men taking daily low-dose tadalafil (2.5-5mg), but these findings remain controversial and have not been consistently replicated. Tadalafil is not indicated for testosterone enhancement, and any observed hormonal changes have been within normal physiological variation and of questionable clinical significance.

Research has explored whether combining tadalafil with testosterone replacement therapy offers advantages over either treatment alone in men with both erectile dysfunction and hypogonadism. Studies suggest that men with low testosterone who do not respond adequately to TRT alone may benefit from adding a PDE5 inhibitor like tadalafil. This combination approach addresses both the hormonal deficit affecting libido and the vascular component of erectile function. However, this represents concurrent treatment of two separate conditions rather than one medication influencing the other.

For men considering treatment, it is essential to understand that tadalafil should not be viewed as a testosterone-boosting agent. If blood tests confirm low testosterone levels, specific hormone replacement therapies—available as gels or injections in the UK—are the appropriate evidence-based treatments. Your GP or specialist can discuss whether you might benefit from tadalafil, testosterone therapy, or both, based on your individual clinical presentation and investigation results.

If you experience any suspected side effects from tadalafil, report them through the MHRA Yellow Card scheme, which helps monitor medication safety.

Treatment Options for Low Testosterone in the UK

In the UK, testosterone replacement therapy (TRT) is the primary evidence-based treatment for confirmed hypogonadism. Before initiating TRT, two separate morning blood tests showing low testosterone levels are required to confirm the diagnosis. UK practice typically considers total testosterone below 8 nmol/L as clearly low, with 8-12 nmol/L considered borderline (requiring assessment of symptoms, SHBG levels, and calculated free testosterone). The MHRA and NICE emphasise that TRT should only be prescribed when biochemical evidence of low testosterone is accompanied by relevant clinical symptoms such as reduced libido, erectile dysfunction, fatigue, decreased muscle mass, or mood disturbances.

Several TRT formulations are currently available through the NHS and private prescription in the UK:

• Transdermal gels (such as Testogel or Tostran) applied daily to the skin, providing steady testosterone levels with flexible dosing

• Intramuscular injections including testosterone undecanoate (Nebido, administered every 10-14 weeks) or mixed testosterone esters (Sustanon, administered every 2-4 weeks), offering convenience for those preferring less frequent dosing

Your GP or endocrinologist will monitor your response to TRT through regular blood tests checking testosterone levels, full blood count (particularly haematocrit, which should not exceed 0.54), and prostate-specific antigen (PSA). Digital rectal examination (DRE) may be performed before and during therapy based on age and risk factors. Initial review typically occurs at 3-6 months, then annually. Men over 50 or those with risk factors for prostate disease require careful monitoring, as TRT is contraindicated in prostate cancer.

Important safety considerations include:

• Fertility impact: TRT suppresses sperm production and is unsuitable when conception is desired. Men planning future fertility should discuss alternatives with a specialist.

• Gel transfer risk: Testosterone gel can transfer to women and children through skin contact. Apply to areas that will be covered by clothing, wash hands thoroughly after application, and avoid skin-to-skin contact at the application site.

• Referral criteria: Endocrinology referral is appropriate for suspected secondary hypogonadism (low testosterone with low/normal LH/FSH), while urology referral may be needed for prostate concerns.

For men with both low testosterone and erectile dysfunction, treatment strategies may include TRT alone initially, as restoring normal testosterone levels often improves erectile function naturally. If erectile difficulties persist despite normalised testosterone levels, adding tadalafil or another PDE5 inhibitor may be appropriate.

When to contact your GP: Seek medical advice if you experience symptoms suggestive of low testosterone, including persistent fatigue, reduced sexual desire, erectile difficulties, mood changes, or decreased muscle strength. Additionally, if you are taking TRT and develop symptoms such as ankle swelling, breathing difficulties, chest pain, or urinary problems, contact your healthcare provider promptly. Never purchase testosterone or tadalafil from unregulated online sources, as these products may be counterfeit, contaminated, or inappropriately dosed, posing significant health risks.

Frequently Asked Questions