Why Is Melatonin Prescription-Only in the UK? What It Does

Melatonin is prescription-only in the UK because it is classed as a medicine, not a food: it is licensed like any other medicine, and the NHS prescribes it mainly for short-term sleep problems in people aged 55 and over, usually for up to 13 weeks, with specialists able to prescribe it for some children and adults.¹ It is not banned. Possessing it is lawful, selling it in the UK without a prescription is not, and anything bought abroad or online is an unlicensed medicine here.¹ Its effect is also smaller than the shopping suggests: across 19 placebo-controlled trials in 1,683 people, melatonin brought sleep about 7 minutes sooner and made it about 8 minutes longer.² Part of the Wellgard ashwagandha guide.

What is melatonin and what does it do to your body?

Melatonin is a hormone made by the pineal gland. Its level rises after dark, peaks in the early hours and falls in daylight, telling the body's clock that it is night. A tablet adds to that supply; the NHS describes it as acting on receptors in the body to encourage sleep, and the trial figures below show the size of that effect.¹ The size of the nudge is known. The 2013 meta-analysis of 19 trials in 1,683 people with primary sleep disorders found sleep onset 7.06 minutes sooner, total sleep 8.25 minutes longer and a small gain in sleep quality (standardised mean difference 0.22); the effect was larger at higher doses and in longer trials, and did not fade with continued use.² "Stops working after four weeks" is not what the trials found, and nor is "knocks you out".

Why is melatonin prescription-only in the UK?

Because of how UK law classifies it. Under the Human Medicines Regulations, a substance used to restore, correct or modify a physiological function is a medicinal product, and melatonin, a hormone taken to alter sleep timing, meets that test; it can be sold only as a licensed medicine, and its UK licences are prescription-only.³ In the United States it has been sold as a dietary supplement since the 1990s, and some countries allow low-dose products over the counter; the UK, like most of Europe, took the medicine route. It is a classification decision, not a safety verdict: the NHS describes melatonin as having few common side effects, with daytime sleepiness, headache, nausea and irritability the ones to know.¹ The medicine route brings the medicine safeguards: a prescriber looks for the cause first, and a pharmacist checks it against your other medicines, many of which alter its sedating effect.¹

What does the NHS prescribe melatonin for?

Three things. Short-term insomnia in adults aged 55 and over, usually for 1 to 4 weeks and in some cases up to 13; longer-term sleep problems in some adults under 55 and in children and teenagers when a specialist recommends it, where a condition such as ADHD, cerebral palsy or chronic fatigue syndrome affects sleep; and jet lag in adults, for up to 5 nights in a row, though the NHS notes that melatonin for jet lag may not be available on an NHS prescription.¹ For children the pathway runs through a paediatrician or another specialist, which is why GPs so often say no when parents ask: most cannot start it, though some continue a specialist's prescription. This page gives no doses; the NHS directs parents to the Medicines for Children website for information on a prescribed product.¹ Anyone with liver or kidney problems or an autoimmune condition tells their doctor before taking it.¹

Can you buy melatonin in the UK, and is it legal to bring it in from abroad?

In the UK you obtain it on prescription, NHS or private. Possessing melatonin is not an offence, but a product bought abroad or ordered online is not licensed for sale here, no UK pharmacist has checked it against your medicines, and a company shipping it to a UK address is supplying a prescription medicine without a prescription.^{1, 3} The NHS puts it plainly: such products "are not authorised for sale in the UK", and ordering melatonin online is not recommended.¹ Gummies are the usual import, and two facts about them matter. In a 2023 analysis of 25 melatonin gummy products sold in the United States, the measured melatonin ranged from about three-quarters of the labelled amount to around three and a half times it, and one product contained none.⁴ A "sleep gummy" on a UK shelf contains something else, and its label says what.

Why don't GPs recommend melatonin more often?

Three reasons, none of them dislike. The licence is narrow: outside the 55-and-over, short-term indication a GP needs a specialist behind the prescription, and local formularies vary. The first-line treatment for insomnia is not a tablet: the NHS offers cognitive behavioural therapy for insomnia, says GPs now rarely prescribe sleeping pills because of side effects and dependence, and limits pharmacy sleep aids containing an antihistamine, valerian or lavender to one or two weeks.⁵ And the effect is 7 and 8 minutes: for a drifted clock those minutes can matter, for 4am waking they usually do not. So "is there a sleeping pill I can take every night, long term?" has an NHS answer: not as a plan. Melatonin is the exception a specialist can make for particular conditions, with reviews.^{1, 5}

Which foods are high in melatonin, and can you raise it naturally?

Foods carry it in nanograms. Montmorency (sour) cherries, the fruit most often sold on this idea, were assayed at 13.46 nanograms of melatonin per gram, so 100 g supplies about 1.3 micrograms, roughly a thousandth of a licensed tablet, and other foods carry less.⁶ No food is "high in melatonin" in a sense that matters to sleep, and the cherry trials that measured a benefit are three small crossover studies, set out on do sour cherries help you sleep. What does move your own melatonin is light: bright mornings and dim, warm evenings set the clock that releases it, and screens before bed delay it, which is why the NHS insomnia advice is about light, timing and caffeine rather than food.⁵ As for "what is 10 times stronger than melatonin": nothing in a supplement has that figure behind it. The phrase is marketing; the fair comparison is below.

What does the evidence say for other sleep ingredients?

Nothing on a UK shelf replaces a prescription medicine, and no supplement may be sold as a melatonin alternative. What exists is ingredients with their own small trials. Ashwagandha: 600 mg of root extract a day for 10 weeks shortened sleep onset by about 5 minutes more than placebo and raised sleep efficiency by about 4 points in 60 people with insomnia.⁷ Magnesium: about 17 minutes faster to fall asleep in three trials of 151 older adults, low to very low quality; does magnesium help you sleep has the detail.⁸ Glycine at 3 g: less next-day fatigue after three nights of restricted sleep.⁹ L-theanine at 200 mg: better sleep-questionnaire scores in 30 adults over four weeks, and a pooled subjective sleep-quality effect of 0.43 across 18 trials.¹⁰ Valerian: more people reporting improved sleep (relative risk 1.37) with no measurable change in time to fall asleep.¹¹ Oral lavender oil: an anxiety score 3.83 points lower than placebo over 10 weeks in three pooled trials of 697 people; in the UK a registered traditional herbal medicine, not a supplement ingredient.¹² None carries an authorised sleep claim in Great Britain; the comparison, dose by dose, is on which sleep supplements have evidence behind them, and anyone on thyroid medicine reads can I take ashwagandha with levothyroxine first. Any sleep powder lawfully sold in the UK is melatonin-free, and the wording it may carry belongs to its nutrients, for example magnesium at 375 mg (100% NRV): magnesium contributes to normal psychological function, to normal functioning of the nervous system and to the reduction of tiredness and fatigue.

Frequently asked questions

Is it harmful to take melatonin every night?

For a prescribed course the NHS says most people have no side effects and the trials found no fading with nightly use; it is prescribed for up to 13 weeks, longer only under a specialist.^{1, 2}

Is melatonin or ashwagandha better for sleep?

Not comparable: one is a licensed medicine with 1,683 people in its pooled trials (7 and 8 minutes), the other a food supplement with 60 people in its best trial (5 minutes and 4 points) and no authorised claim.^{2, 7}

What is a safe sleep aid to take every night?

The NHS's long-term answer is cognitive behavioural therapy for insomnia, not a product; pharmacy sleep aids are for one to two weeks, and a supplement stays within its label dose.⁵

What will a doctor prescribe if I can't sleep?

Often nothing at first: a check for causes (pain, thyroid, mood, menopause, medicines), sleep-habit changes and CBT for insomnia; melatonin if you are 55 or over and the problem is short-term; sleeping tablets rarely and briefly.⁵

Is melatonin now legal in the UK?

It has always been legal as a prescription medicine and nothing has changed: prescription-only, with online or imported supply unlicensed.¹

Sources

1. NHS. Melatonin (all pages). nhs.uk/medicines/melatonin.
2. Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One, 2013. PubMed 23691095.
3. The Human Medicines Regulations 2012, SI 2012/1916. legislation.gov.uk.
4. Cohen PA, et al. Quantity of melatonin and CBD in melatonin gummies sold in the US. JAMA, 2023. PubMed 37097362.
5. NHS. Insomnia. nhs.uk/conditions/insomnia.
6. Burkhardt S, et al. Detection and quantification of the antioxidant melatonin in Montmorency and Balaton tart cherries. Journal of Agricultural and Food Chemistry, 2001. PubMed 11600041.
7. Langade D, et al. Efficacy and safety of ashwagandha root extract in insomnia and anxiety: a double-blind, randomized, placebo-controlled study. Cureus, 2019. PubMed 31728244.
8. Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 2021. PubMed 33865376.
9. Bannai M, et al. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. Frontiers in Neurology, 2012. PubMed 22529837.
10. Hidese S, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Nutrients, 2019. PubMed 31623400; Bulman A, et al. The effects of L-theanine consumption on sleep outcomes: a systematic review and meta-analysis. Sleep Medicine Reviews, 2025. PubMed 40056718.
11. Fernández-San-Martín MI, et al. Effectiveness of valerian on insomnia: a meta-analysis of randomized placebo-controlled trials. Sleep Medicine, 2010. PubMed 20347389.
12. Möller HJ, et al. Efficacy of Silexan in subthreshold anxiety: meta-analysis of randomised, placebo-controlled trials. European Archives of Psychiatry and Clinical Neuroscience, 2019. PubMed 29150713.