Is melatonin good for erectile dysfunction? This question has gained attention as melatonin's antioxidant properties and effects on blood vessel function have prompted interest beyond its established role in sleep regulation. Melatonin is a hormone produced by the pineal gland that regulates the sleep-wake cycle and is available in the UK as a prescription-only medicine for primary insomnia in adults over 55. Whilst theoretical mechanisms suggest potential benefits for erectile function, robust clinical evidence is lacking. This article examines the current evidence, explores the biological rationale, and outlines established treatments for erectile dysfunction in line with UK guidance.

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

Melatonin is a naturally occurring hormone produced primarily by the pineal gland in the brain. Its production is regulated by light exposure, with levels rising in the evening as darkness falls and declining during daylight hours. This circadian rhythm helps regulate the sleep-wake cycle, making melatonin essential for maintaining healthy sleep patterns.

Beyond its role in sleep regulation, melatonin functions as an antioxidant and has been shown to influence various physiological processes throughout the body. It interacts with specific melatonin receptors (MT1 and MT2) found in numerous tissues, including the brain, cardiovascular system, immune system, and reproductive organs. Through these receptors, melatonin helps modulate inflammation, oxidative stress, and cellular function.

In the UK, melatonin is available as a prescription-only medicine. The modified-release preparation (Circadin 2 mg) is licensed by the MHRA for the short-term treatment (up to 13 weeks) of primary insomnia characterised by poor quality of sleep in adults aged 55 years and over. It is typically taken 1-2 hours before bedtime after food. Melatonin is sometimes prescribed off-licence for jet lag and sleep disorders in younger adults and children, though this should be under medical supervision.

The hormone's antioxidant properties have generated research interest in its potential effects on conditions associated with oxidative stress and inflammation, including cardiovascular disease, metabolic disorders, and age-related conditions. However, it is important to distinguish between melatonin's established role in sleep regulation and emerging research into other potential therapeutic applications, which remain largely investigational and require further clinical validation.

The Link Between Melatonin and Erectile Dysfunction

Erectile dysfunction (ED) is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. It affects a significant proportion of men, particularly those over 40 years of age, and can result from vascular, neurological, hormonal, or psychological factors. Increasingly, research has identified oxidative stress and endothelial dysfunction as important contributors to ED, particularly in men with cardiovascular risk factors or diabetes.

The theoretical connection between melatonin and erectile function stems from several biological mechanisms, primarily based on animal and laboratory studies rather than robust human clinical evidence. Firstly, melatonin's antioxidant properties may help protect the endothelial cells lining blood vessels from oxidative damage, potentially improving blood flow to the penis. Secondly, melatonin influences nitric oxide (NO) pathways, which are crucial for smooth muscle relaxation in the corpus cavernosum—the erectile tissue of the penis. Adequate NO production is essential for achieving and maintaining erections.

Additionally, sleep quality and erectile function are interconnected. Poor sleep, particularly conditions like obstructive sleep apnoea (OSA), is associated with increased rates of ED. While treating OSA with continuous positive airway pressure (CPAP) or weight loss can improve erectile function, melatonin's role is limited to potentially improving sleep quality rather than treating OSA itself. It's also worth noting that melatonin may influence reproductive hormone signalling in some contexts, though the clinical significance of these effects remains uncertain and could potentially be inhibitory in some settings.

However, it is crucial to note that there is no official link established between melatonin supplementation and improvement in erectile dysfunction. The mechanisms described above are largely theoretical or based on preclinical research, and robust clinical evidence in humans is currently lacking.

Current Evidence: Does Melatonin Help With Erectile Dysfunction?

The scientific evidence examining melatonin's direct effect on erectile dysfunction in humans is extremely limited. Most available research consists of animal studies and small-scale investigations that do not provide sufficient evidence to support clinical recommendations. A few animal studies have suggested that melatonin may have protective effects on erectile tissue in models of diabetes or oxidative stress, but these findings cannot be reliably extrapolated to human clinical practice.

There are no large-scale, randomised controlled trials—the gold standard of medical evidence—that have specifically evaluated melatonin as a treatment for ED in men. The existing human studies are often confounded by small sample sizes, lack of placebo controls, or investigation of melatonin for other primary outcomes (such as sleep) with erectile function measured only as a secondary endpoint. Consequently, current evidence does not support the use of melatonin as a treatment for erectile dysfunction.

Some observational research has explored the relationship between endogenous melatonin levels and sexual function, with mixed results. Certain studies have suggested that disrupted melatonin rhythms or low melatonin levels might correlate with sexual dysfunction, but correlation does not establish causation. Other factors such as age, comorbidities, medications, and lifestyle factors are likely to confound these associations.

NICE guidance on the assessment and management of erectile dysfunction does not include melatonin among recommended treatment options. The evidence base remains insufficient to justify its use for this indication, and men experiencing ED should be offered established, evidence-based therapies. Further high-quality research would be needed before any clinical recommendations regarding melatonin and erectile function could be made.

Established Treatments for Erectile Dysfunction in the UK

NICE provides clear guidance on the management of erectile dysfunction, emphasising a stepwise approach that begins with lifestyle modification and addresses underlying causes. Initial assessment should include a thorough medical and sexual history, physical examination, and relevant investigations such as cardiovascular risk assessment, HbA1c or fasting glucose, lipid profile, blood pressure, urinalysis, and early morning total testosterone (repeated if low). TSH and prolactin levels may be considered if hypogonadism is suspected.

Lifestyle interventions form the foundation of ED management and include:

• Weight loss in men who are overweight or obese

• Increased physical activity and regular exercise

• Smoking cessation

• Reduction in alcohol consumption

• Optimisation of diabetes control and cardiovascular risk factors

Phosphodiesterase type 5 (PDE5) inhibitors are the first-line pharmacological treatment for ED in the UK. These include sildenafil, tadalafil, vardenafil, and avanafil. They work by enhancing the effects of nitric oxide, promoting smooth muscle relaxation and increased blood flow to the penis during sexual stimulation. PDE5 inhibitors are effective in approximately 70% of men and are generally well tolerated. They are contraindicated in men taking nitrates, nicorandil or riociguat due to the risk of severe hypotension. Caution is needed with alpha-blockers, and they should be avoided in unstable cardiovascular disease or recent myocardial infarction/stroke until the condition is stabilised. Tadalafil is available in both on-demand and daily dosing regimens, with the latter offering more continuous coverage.

For men who do not respond to or cannot tolerate PDE5 inhibitors, second-line treatments include:

• Intracavernosal injections (e.g., alprostadil)

• Intraurethral alprostadil

• Vacuum erection devices

Referral to specialist services is indicated for men with non-response to treatment, suspected Peyronie's disease or penile deformity, or suspected endocrine disorders. Depending on the underlying issue, referral may be to urology/andrology, endocrinology, psychosexual therapy, or cardiology for risk assessment.

Psychological interventions, including psychosexual counselling or cognitive behavioural therapy, should be considered when psychological factors contribute to ED or when anxiety about sexual performance is present. Many men benefit from a combination of pharmacological and psychological approaches. Testosterone replacement therapy may be appropriate in men with confirmed hypogonadism, though this should be initiated and monitored by specialists.

Safety Considerations When Using Melatonin

While melatonin is generally considered safe for short-term use in the licensed indication (primary insomnia in adults over 55), it is not without potential adverse effects and drug interactions. Common side effects include headache, dizziness, drowsiness, and nausea. Some individuals may experience daytime sleepiness, which can impair driving ability and the operation of machinery. Patients should be advised to assess their response to melatonin before engaging in such activities.

Melatonin can interact with several medications. Specific interactions include:

• Fluvoxamine: significantly increases melatonin levels and should be avoided

• Cimetidine, quinolone antibiotics and oestrogens: may increase melatonin levels

• Carbamazepine, rifampicin and smoking: may reduce melatonin levels

• Alcohol: should be avoided as it may impair sleep quality and potentially interact with melatonin

• Warfarin and other coumarins: closer INR monitoring is advised if co-prescribed

• Antihypertensives: melatonin may cause a small reduction in blood pressure; monitoring is advised

Melatonin is not recommended during pregnancy or breastfeeding unless specifically advised by a specialist.

Important safety advice for patients considering melatonin:

• Melatonin is a prescription-only medicine in the UK and should not be obtained from unregulated sources

• It is not licensed or recommended for the treatment of erectile dysfunction

• Self-medication with melatonin for ED may delay appropriate investigation and treatment of underlying causes

• Men experiencing erectile dysfunction should consult their GP for proper assessment

Patients should seek medical attention if they experience persistent ED, as it may be an early indicator of cardiovascular disease, diabetes, or other significant health conditions. Red flag symptoms requiring urgent medical review include ED associated with perineal or genital numbness, loss of bladder or bowel control (which may indicate cauda equina syndrome), or ED following pelvic trauma or surgery.

Patients should report any suspected side effects from melatonin to the MHRA through the Yellow Card scheme (yellowcard.mhra.gov.uk or via the Yellow Card app).

In summary, while melatonin has an established role in sleep regulation, there is insufficient evidence to support its use for erectile dysfunction. Men with ED should be offered evidence-based treatments in line with NICE guidance, following appropriate clinical assessment.

Frequently Asked Questions