Melatonin: the sleep aid that needs a prescription in the UK
The MHRA found melatonin that was not on the label in a children’s gummy product sold online as a food supplement.
Melatonin, which can be bought in health food shops or online in some countries, is a prescription-only medicine in the UK, according to the NHS.
Supplements of that kind are not authorised for sale in the UK, and the NHS adds that ordering melatonin online is not recommended.
In August 2025, the Medicines and Healthcare products Regulatory Agency (MHRA) advised parents and caregivers to stop all use of Nutrition Ignition Kids Magnesium Glycinate Gummies, a product sold only online as a food supplement. Testing of two batches found between 1.5mg and 1.7mg of melatonin in each gummy, and the packaging did not list it, the agency said.
What melatonin is
The NHS describes melatonin as a hormone that occurs naturally in the body and helps control how and when a person sleeps. A synthetic version, which people can take for short periods if they have sleep problems such as insomnia, adds to that natural supply, so they fall asleep more quickly and are less likely to wake during the night.
Under NHS guidance, most adults aged 55 and over can take melatonin for short-term sleep problems. Adults under 55 and children with longer-term sleep problems can take it if a specialist recommends it. Anyone who still has sleep problems after a course should speak to a doctor, the NHS says.
Jet lag
A Cochrane review by Herxheimer and Petrie, published in 2002, covered 10 trials. Eight of them found that melatonin, taken close to the target bedtime at the destination, decreased jet lag on flights crossing five or more time zones. The reviewers wrote that occasional short-term use appears to be safe, but that case reports suggest people with epilepsy, and patients taking warfarin, may come to harm from it. The review’s last search for new studies was in 2008.
The NHS says melatonin for jet lag may not be available on NHS prescription.
Side effects and warnings
The NHS says most people will not have any side effects, though some may get a headache, or feel tired, sick or irritable the day after taking melatonin. Its side-effects page says serious side effects are rare and happen to less than 1 in 1,000 people.
The same page says anyone who starts feeling low or sad should speak to a doctor, as this could be a sign of depression. It says a doctor or 111 should be called now for any of these:
- changes to eyesight, such as blurred vision
- feeling faint or passing out
- feeling confused or dizzy, or things seeming to spin around (vertigo)
- bleeding that does not stop, unexplained bruising or blood in the urine
In rare cases melatonin can also cause a serious allergic reaction, and the page lists the warning signs that need an immediate call to 999.
People should tell a doctor or pharmacist before taking melatonin in these cases, the NHS says:
- ever having had an allergic reaction to melatonin or any other medicine
- liver or kidney problems
- rheumatoid arthritis, multiple sclerosis or lupus, or any other autoimmune condition
The NHS also says alcohol and melatonin together can make people sleep very deeply, so that they do not breathe properly and can have difficulty waking up.
The NHS pages were last reviewed on 13 February 2023, with the next review listed as due in February 2026. The MHRA says suspected side effects from any medicine should be reported to its Yellow Card scheme.