Melatonin
N-acetyl-5-methoxytryptamine
Sold freely in United States and unregulated in Japan. Same substance, same evidence, different decisions.
A hormone the body makes to signal night; sold for sleep and jet lag.
Melatonin is the clearest case in the world of one substance treated two completely different ways. In the United States it is a cheap supplement sold in gas stations; across most of Europe, the UK, Japan and Australia it is a prescription medicine. The split comes down to a single question: is melatonin a food-like supplement, or a hormone that acts on the body and therefore a drug? Nothing about the molecule changes at the border, only the legal philosophy does.
Where it stands, jurisdiction by jurisdiction
United States
Open, sold freelyDecided on: Industry protection, Contested
Sold over the counter as a dietary supplement under the Dietary Supplement Health and Education Act of 1994, in doses from about 0.5 mg to 10 mg or more, as tablets, gummies and liquids. The FDA does not review supplements for efficacy or dose accuracy before sale and acts only after a product reaches the market, so independent testing has found actual melatonin content ranging well above and below the label.
Canada
Open, sold freelyDecided on: Precaution, Evidence
For adults it is available without prescription as a licensed Natural Health Product carrying a Natural Product Number, under the Natural and Non-prescription Health Products Directorate melatonin monographs, which authorize adult use only. Following a public consultation, Health Canada amended the Prescription Drug List so that all sleep-related use in children and adolescents under 18 now requires a prescription; that change is in force. Adult NHP products are unaffected.
United Kingdom
Prescription, prescription onlyDecided on: Precaution
Prescription-only; there is no licensed melatonin supplement in the UK. The NHS prescribes it mainly as prolonged-release Circadin 2 mg for short-term insomnia in adults aged 55 and over, and separately as Slenyto for sleep problems in some children. It cannot be bought over the counter at any dose. Possessing it for personal use is not an offence, but selling it without a marketing authorization is.
European Union
Prescription, prescription onlyDecided on: Precaution, Contested
Melatonin medicines are centrally authorized and prescription-only, including prolonged-release Circadin for insomnia in adults aged 55 and over and Slenyto for children with autism spectrum disorder or Smith-Magenis syndrome. Outside those authorized medicines, member states differ: some allow low-dose melatonin as a food supplement, while higher doses are generally treated as medicinal, so the same product can be a supplement in one country and a medicine in another.
Australia
Restricted, restrictedDecided on: Precaution
Scheduled under the Poisons Standard. Following a 2021 down-scheduling, modified-release melatonin of 2 mg or less is Schedule 3 (pharmacist-only, no prescription) for short-term insomnia in adults aged 55 and over, and immediate-release melatonin of 5 mg or less is Schedule 3 for jet lag in adults 18 and over. All other melatonin remains Schedule 4 (prescription-only). It is not sold as an ordinary supplement.
South Africa
Restricted, restrictedDecided on: Precaution
Scheduled under the SAHPRA Consolidated Schedules. Used for desynchronosis (jet lag) at 6 mg per day or less it is Schedule 2, which a pharmacist can supply without a prescription under set conditions; for all other uses it is Schedule 4 (prescription-only). Circadin is registered as a Schedule 4 medicine.
Japan
Unregulated, unregulated, sold anywayDecided on: Precaution, Contested
Treated as a pharmaceutical rather than a food and not sold over the counter as a supplement. Travelers bringing personal-use melatonin may need an import certificate from the Ministry of Health, Labour and Welfare, now called a Yunyu Kakunin-sho (formerly Yakkan Shoumei), obtained in advance depending on the quantity carried.
Regulatory positions change, sometimes quickly. Check the date on a source before relying on it.