Melatonin is a hormone that occurs naturally in your body. It helps control your sleep patterns.

You can take a manmade version of melatonin for short-term sleep problems (insomnia). It makes you fall asleep quicker and less likely to wake up during the night. It can also help with symptoms of jetlag.

Melatonin is used to treat sleep problems in people aged 55 and over.

It can sometimes be prescribed to help with sleep problems in children and to prevent headaches in adults.

Melatonin is available on prescription only. It comes as slow-release tablets and a liquid that you drink.

• Melatonin is mainly used to treat sleep problems in adults aged 55 or older.
• You'll usually take it for 1 to 4 weeks.
• Some people may get a headache after taking melatonin, or feel tired, sick or irritable the next day.
• Avoid drinking alcohol or smoking while taking melatonin. These stop the medicine working as well as it should.
• Melatonin is also known by the brand name Circadin.

Melatonin is mainly prescribed for adults aged 55 or over, to help for short-term sleep problems.

It can sometimes be used by adults under the age of 55 and by children, if their doctor recommends it.

It's not suitable for some people. To make sure melatonin is safe for you, tell your doctor if you:

• have had an allergic reaction to melatonin or any other medicines in the past
• have liver or kidney problems
• have rheumatoid arthritis, multiple sclerosis or lupus, or any other autoimmune condition

The dose will vary depending on why you're taking it. Follow the instructions that come with your medicine if you're taking melatonin to:

• prevent headaches
• treat jet lag

If your child is prescribed melatonin, follow the doctor's instructions carefully. Find out more about giving melatonin to children from Medicines for Children.

For sleep problems in adults

Your doctor will prescribe 2mg slow-release (or prolonged-release) tablets. These release melatonin gradually into your body during the night.

It's important to follow the instructions carefully. Your doctor may tell you to take melatonin only 2 or 3 times a week, and not every night.

You'll usually take melatonin for just a few weeks to help with short-term sleep problems (insomnia). However, it is sometimes prescribed for up to 13 weeks.

How to take it

For sleep problems in adults, the usual dose is one 2mg tablet. Take the tablet 1 to 2 hours before bedtime. This is because the medicine takes a couple of hours to start working.

Take melatonin after food.

Swallow the tablet whole. Do not crush or chew it.

What if I forget to take it?

If you forget to take melatonin by bedtime, skip the missed dose and start again the next night.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

What if I take too much?

If you take 1 or 2 extra tablets of melatonin by accident, it's unlikely to harm you.

If you need to go to hospital, take the melatonin packet or leaflet inside it, plus any remaining medicine, with you.

Ask someone to go with you to hospital as you may start to feel very sleepy on the way. If you're travelling by car, do not drive yourself.

Most people will not have any side effects when taking melatonin.

Common side effects

These common side effects happen in more than 1 in 100 people.

Talk to your doctor or pharmacist if these side effects bother you or do not go away:

• feeling sleepy or tired in the daytime
• headache
• stomach ache or feeling sick (nausea)
• feeling dizzy
• feeling irritable or restless
• dry mouth
• dry or itchy skin
• pains in your arms or legs
• strange dreams or night sweats

Serious side effects

Serious side effects are rare and happen to less than 1 in 1,000 people.

Speak to a doctor as soon as possible if you:

• start feeling low or sad – this could be a sign of depression
• get blurry vision or your eyes become more watery than usual
• feel faint or pass out
• start feeling confused or dizzy, or things seem to be spinning around you (vertigo)
• have any bleeding that does not stop, unexplained bruising or blood in your urine
• get psoriasis

Serious allergic reaction

In rare cases, it's possible to have a serious allergic reaction (anaphylaxis) to melatonin.

What to do about:

• feeling sleepy or tired in the daytime – do not drive, cycle or use tools or machinery if you're feeling this way. Do not drink any alcohol as this will make you feel more tired. If this does not help, talk to your doctor as melatonin may not be the right medicine for you.
• headache – make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask a pharmacist to recommend a painkiller. Talk to a doctor if headaches last longer than a week or are severe.
• stomach ache or feeling sick (nausea) – take your medicine after food. It can help to eat and drink slowly and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your tummy may also help ease any pain.
• feeling dizzy – if taking melatonin makes you feel dizzy, stop what you're doing and sit or lie down until you feel better. Do not drive, cycle or use tools or machinery if you're feeling dizzy. Do not drink alcohol as it will make you feel worse.
• feeling irritable or restless – if this does not get better after a few days, stop taking the medicine and talk to your doctor.
• dry mouth – chew sugar-free gum or suck sugar-free sweets.
• dry or itchy skin – apply a moisturiser often. Try using an oil-free face moisturiser for sensitive skin.
• pains in your arms or legs – if this does not get better after a few days, stop taking the medicine and talk to your doctor.
• strange dreams or night sweats – if this does not get better after a few days, stop taking the medicine and talk to your doctor.

It's best to avoid taking melatonin if you're pregnant or if you want to breastfeed. Not enough research has been done to know whether it's safe for you and your baby.

Melatonin passes into breast milk in small amounts and this can make a baby more sleepy. If you want to breastfeed, talk to a doctor or midwife first before taking melatonin.

Some medicines and melatonin can interfere with each other and increase your risk of side effects.

Certain medicines may increase or decrease the drowsy-making (sedating) effects of melatonin.

Speak to a doctor or pharmacist before taking melatonin if you take any of the following:

• antidepressants such as fluvoxamine or imipramine
• blood pressure lowering medicines
• nonsteroidal anti-inflammatory medicines (NSAIDs) such as ibuprofen, naproxen or diclofenac
• oestrogens (used in contraceptives and hormone replacement therapy)
• opiate agonists or antagonists (for drug addiction)
• psoralens (for skin disorders such psoriasis)
• quinolones or rifampicin (types of antibiotic)
• carbamazepine (for epilepsy)
• cimetidine (for stomach problems such as ulcers)
• thioridazine (for schizophrenia)
• tryptophan supplements (for insomnia)
• warfarin (a blood thinner)
• zaleplon, zolpidem or zopiclone (for insomnia)

Mixing melatonin with herbal remedies and supplements

Do not take any herbal remedies that make you feel sleepy while taking melatonin.

They can increase the sedating effects of your medicine and make you feel much more drowsy.