Does tadalafil improve athletic performance? This question has gained attention among athletes seeking competitive advantages, but the evidence does not support its use as a performance enhancer. Tadalafil is a prescription medicine licensed in the UK for erectile dysfunction and benign prostatic hyperplasia, not for sport. Whilst its vasodilatory effects have prompted speculation about improved oxygen delivery to muscles, research remains inconclusive and does not demonstrate meaningful benefits for healthy athletes. Using tadalafil outside its licensed indications carries significant health risks, including cardiovascular complications during exercise. This article examines the evidence, explores potential dangers, and highlights safe, evidence-based strategies to enhance athletic performance.

What Is Tadalafil and How Does It Work in the Body?

Tadalafil is a prescription medicine licensed in the UK primarily for the treatment of erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). It belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil and vardenafil. Tadalafil is available under brand names such as Cialis and as generic formulations, and is regulated by the Medicines and Healthcare products Regulatory Agency (MHRA).

The drug works by inhibiting the PDE5 enzyme, which is responsible for breaking down cyclic guanosine monophosphate (cGMP) in smooth muscle cells. When PDE5 is blocked, cGMP levels increase, leading to relaxation of smooth muscle and vasodilation (widening of blood vessels). In the context of erectile dysfunction, this increased blood flow to the penis facilitates an erection in response to sexual stimulation. Tadalafil also causes vasodilation in the pulmonary arteries, which is why a higher-dose formulation (Adcirca and generics) is licensed for pulmonary arterial hypertension.

Tadalafil is absorbed relatively quickly after oral administration, with peak plasma concentrations reached within two hours. It has a notably long half-life of approximately 17.5 hours, which distinguishes it from other PDE5 inhibitors and allows for more flexible dosing. The drug is metabolised primarily in the liver by the CYP3A4 enzyme system and excreted via faeces and urine.

Tadalafil is contraindicated in patients taking nitrates (such as glyceryl trinitrate or isosorbide mononitrate for angina), guanylate cyclase stimulators like riociguat, and in those with recent cardiovascular events (heart attack, stroke, unstable angina), severe hypotension, or uncontrolled arrhythmias. Caution is needed in severe renal or hepatic impairment.

While tadalafil's vasodilatory effects have led to speculation about potential benefits in athletic performance—particularly regarding blood flow and oxygen delivery to muscles—it is not licensed or approved for use as a performance-enhancing agent. Any use outside its licensed indications is considered off-label and should be approached with caution.

Does Tadalafil Improve Athletic Performance? Examining the Evidence

The question of whether tadalafil can enhance athletic performance has been explored in a limited number of studies, but the evidence remains inconclusive and does not support its use as an ergogenic aid. Some research has investigated whether the vasodilatory properties of PDE5 inhibitors might improve oxygen delivery to working muscles, reduce fatigue, or enhance endurance capacity.

A small number of studies have examined tadalafil's effects on exercise performance at high altitude, where reduced oxygen availability can impair physical capacity. The rationale is that pulmonary vasodilation might counteract altitude-induced pulmonary hypertension and improve oxygenation. However, results have been mixed and inconsistent. Some trials reported modest improvements in exercise capacity or reduced pulmonary artery pressure, while others found no significant benefit. Importantly, these studies typically involved small sample sizes (often fewer than 20 participants) and specific environmental conditions that do not translate to general athletic performance at sea level.

Research conducted at normal altitude has generally shown no meaningful improvement in aerobic performance, strength, or endurance among healthy athletes taking tadalafil. Reviews of available evidence on PDE5 inhibitors and exercise performance have concluded that there is insufficient evidence to recommend their use for enhancing athletic capacity in healthy individuals.

It is also important to note that the World Anti-Doping Agency (WADA) does not currently list tadalafil as a prohibited substance. However, this does not imply endorsement or safety for performance enhancement. Athletes should always check the current status of any substance with UK Anti-Doping (UKAD) or WADA, as prohibited lists are updated annually.

In summary, there is no official link or credible scientific consensus supporting tadalafil as an effective performance enhancer for athletes. Its use for this purpose is not evidence-based and carries potential risks.

Potential Risks of Using Tadalafil for Exercise or Sport

Using tadalafil outside its licensed indications—such as for athletic performance enhancement—carries significant health risks and is not recommended. Even when used appropriately for erectile dysfunction or benign prostatic hyperplasia, tadalafil can cause a range of adverse effects, some of which may be particularly problematic during physical exertion.

Common side effects of tadalafil include:

• Headache – reported in up to 15% of users

• Flushing (redness and warmth of the skin)

• Indigestion or dyspepsia

• Nasal congestion

• Back pain and muscle aches – which may appear 12–24 hours after dosing

• Dizziness

More serious, though less common, adverse effects include:

• Hypotension (low blood pressure) – particularly concerning during intense exercise, which already places cardiovascular demands on the body. The combination may lead to fainting, falls, or inadequate perfusion of vital organs.

• Cardiovascular events – individuals with underlying heart conditions are at increased risk. Tadalafil is absolutely contraindicated in patients taking nitrates (including recreational nitrites or 'poppers') as the combination can cause life-threatening drops in blood pressure.

• Priapism – a prolonged, painful erection lasting more than four hours, which is a medical emergency.

• Visual disturbances – including changes in colour vision or sudden vision loss, which may indicate non-arteritic anterior ischaemic optic neuropathy (NAION).

• Sudden hearing loss – a rare but serious side effect.

Drug interactions are another concern. Tadalafil can interact with:

• Nitrates and guanylate cyclase stimulators (riociguat) – contraindicated

• Antihypertensives and alpha-blockers – increased risk of hypotension

• CYP3A4 inhibitors (e.g., clarithromycin, erythromycin, itraconazole, ketoconazole, ritonavir) – increased tadalafil exposure

• CYP3A4 inducers (e.g., rifampicin, carbamazepine, phenytoin, St John's wort) – reduced tadalafil effectiveness

• Grapefruit juice – may increase tadalafil levels

Athletes considering tadalafil should be aware that self-medicating without medical supervision increases the risk of inappropriate dosing, unrecognised contraindications, and dangerous interactions. If you experience chest pain, severe dizziness, visual changes, or prolonged erection, seek immediate medical attention. Suspected side effects should be reported via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

Safe and Evidence-Based Ways to Enhance Athletic Performance

Rather than seeking unproven pharmacological shortcuts, athletes should focus on evidence-based strategies that safely and effectively enhance performance. These approaches are supported by robust research and align with guidance from organisations such as NICE, Sport England, and UK Anti-Doping.

Structured training programmes remain the cornerstone of performance improvement. Periodised training that incorporates progressive overload, adequate recovery, and sport-specific conditioning leads to measurable gains in strength, endurance, and skill. Working with qualified coaches or sports scientists can optimise training adaptations.

Nutrition and hydration play critical roles in athletic performance. A balanced diet that meets energy requirements and provides adequate macronutrients (carbohydrates, protein, and fats) and micronutrients supports training adaptations and recovery. Sports dietitians registered with the British Dietetic Association can provide individualised guidance. Proper hydration before, during, and after exercise is essential for maintaining performance and preventing heat-related illness.

Sleep and recovery are often underestimated but are vital for performance gains. Aim for 7–9 hours of quality sleep per night to support muscle repair, cognitive function, and hormonal balance. Active recovery, massage, and appropriate rest days help prevent overtraining syndrome.

Evidence-based supplements may offer modest benefits in specific contexts, though effects vary between individuals. These include:

• Caffeine – improves endurance and high-intensity performance

• Creatine monohydrate – enhances strength and power in short-duration, high-intensity activities

• Beta-alanine – may improve performance in events lasting 1–4 minutes

• Nitrate-rich beetroot juice – some evidence for improved endurance

Always choose supplements that are batch-tested by programmes such as Informed Sport to minimise contamination risk. Check the current status of any supplement with UK Anti-Doping (UKAD) or WADA to ensure compliance with anti-doping regulations.

Medical optimisation is also important. If you experience unexplained fatigue, poor recovery, or declining performance, consult your GP. Conditions such as anaemia, thyroid disorders, or vitamin D deficiency can impair athletic capacity and are treatable.

Finally, mental skills training, including goal-setting, visualisation, and stress management, can enhance performance and resilience. Sport psychologists accredited by the British Association of Sport and Exercise Sciences (BASES) can provide professional support.

If you are considering any supplement or intervention to enhance performance, discuss it with your GP or a registered sports medicine professional to ensure it is safe, legal, and appropriate for your individual circumstances.

Frequently Asked Questions