Melatonin is not illegal in the UK, but it is a prescription-only medicine. You cannot buy it over the counter in pharmacies or shops the way you can in the United States, Canada, or much of Europe. Possessing melatonin for personal use is not a criminal offense, but selling it without authorization is against UK medicines regulations.
Why Melatonin Requires a Prescription
The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) classifies melatonin as a prescription-only medicine rather than a dietary supplement. This means no retailer, pharmacy, or health food store in the UK can legally sell it without a doctor’s prescription. There is no licensed melatonin supplement in the UK at all.
The reasoning comes down to how the UK regulates anything that affects the body’s chemistry. While the US Food and Drug Administration allows melatonin to be sold as a supplement with minimal oversight, UK regulators treat it as a medicine that should be monitored by a doctor. Common side effects include headache and drowsiness, and regulators have flagged concerns about excessive sleepiness when melatonin is taken at the wrong time, particularly before travel days for jet lag.
Who Can Get a Prescription
The most well-known prescribed form is Circadin, a 2 mg prolonged-release tablet licensed for adults aged 55 and over with poor-quality sleep. The recommended dose is 2 mg taken once daily, one to two hours before bedtime with food, for up to thirteen weeks. The tablets need to be swallowed whole to work properly.
Beyond that specific license, doctors can prescribe melatonin more broadly. Adults with short-term or longer-term insomnia may receive it. People with conditions that disrupt sleep, including ADHD, cerebral palsy, and chronic fatigue syndrome, can be prescribed melatonin on a longer-term basis, typically by a specialist. It is also licensed for the short-term treatment of jet lag.
Children and teenagers with sleep problems can receive melatonin too, though this is usually prescribed by a specialist rather than a GP. For children with ADHD, professional guidelines suggest melatonin can help advance sleep onset times, though experts note that behavioral interventions (consistent bedtime routines, reducing screen time) often work well for childhood sleep problems and are typically tried first. The long-term effects of melatonin in children are still not fully understood.
Can You Buy It Online?
The NHS explicitly recommends against ordering melatonin online without a prescription, citing the risks of buying unregulated medicines. Melatonin supplements sold on international websites are not authorized for sale in the UK. Products shipped from overseas may vary widely in actual melatonin content, contain unlisted ingredients, or arrive in doses much higher than what a UK doctor would prescribe.
That said, legitimate UK-registered online pharmacies can dispense melatonin if a prescriber reviews your medical history and issues a prescription through their service. The key distinction is whether an actual prescriber is involved in the process. If a website lets you add melatonin to a cart and check out like any other product, it is not operating within UK law.
Bringing Melatonin Into the UK
If you bought melatonin over the counter abroad, you can bring it into the UK for personal use. UK customs rules allow you to carry up to a three-month supply of medicine for personal use when entering the country. If you are not a UK resident, you need a letter confirming the medicine was prescribed for you, including your name, travel dates, a list of the medicines with doses and quantities, and the prescriber’s signature.
Melatonin is not a controlled substance, so there are no special licenses or declarations required. However, if you bring more than three months’ supply or have additional melatonin posted to you from abroad, customs can confiscate the excess.
How the UK Differs From Other Countries
The UK’s approach is stricter than most. In the United States, melatonin is one of the most popular supplements on the market, available in gummy form at gas stations in doses up to 10 mg or more. Australia takes a similar approach to the UK, requiring a prescription for higher doses while allowing a very low-dose version (under 2 mg) over the counter. Most EU countries fall somewhere in between, with some allowing low-dose melatonin as a food supplement.
The practical result for UK residents is straightforward: if you want melatonin, your route is through a GP, a specialist, or a registered online pharmacy with a prescriber. It is not a substance you will face legal trouble for possessing, but it is not one you can simply pick up off the shelf.