Your dose of melatonin will depend on why you're taking it.
Whatever you're taking melatonin for, follow the instructions that come with your medicine.
Dosage and strength
Melatonin usually comes as 2mg, slow release tablets. These release melatonin gradually into your body during the night.
For short-term sleep problems (insomnia) in adults
The usual dose is one 2mg slow release tablet taken 1 to 2 hours before bedtime.
Sometimes your doctor will recommend that you only take melatonin 2 or 3 times a week to see if that improves your sleep first.
Melatonin should only be taken for a maximum of 13 weeks to treat short-term sleep problems in adults, but longer courses may be used on the advice of a specialist.
For longer-term sleep problems (insomnia) in adults
There are a number of conditions, including ADHD, cerebral palsy and chronic fatigue syndrome, which may affect your sleep. If you have a condition-related sleep problem, a specialist may prescribe melatonin longer term.
The usual starting dose is one 2mg slow release tablet taken 30 minutes to 1 hour before bedtime.
Sometimes the dose may gradually be increased to 2 to 3 tablets before bedtime, depending on how well it works and whether you have any side effects. The maximum dose is 5 tablets (10mg) once daily.
For longer-term sleep problems in children and teenagers
Longer-term treatment for children and teenagers is usually prescribed by a specialist.
The usual starting dose is one 2mg slow release tablet taken 30 minutes to 1 hour before bedtime. The dose may gradually be increased (up to a maximum of 10mg once daily) depending on how well it works and whether they have any side effects.
If their doctor prescribes melatonin liquid, they should follow the instructions provided with the medicine.
For treatment of jet lag in adults
The usual dose for jet lag is one 3mg standard tablet. You can take this once a day for up to 5 days.
When you arrive at your destination, take your first dose at your normal bedtime. This should not be before 8pm or after 4am.
If you still need to take doses after this, try to take them at a similar time.
You can increase your dose to up to two 3mg tablets (6mg) if you need to.
Do not use more than 16 treatment courses in a year.
How to take it
It's best to take melatonin with food.
If you're taking slow release tablets, swallow them whole and do not cut or crush them.
How long to take it for
For short-term sleep problems you'll usually take melatonin for 1 to 4 weeks, although in some cases it can be prescribed for up to 13 weeks.
If you still have sleeping problems after finishing your course of melatonin, speak to your doctor.
If you need treatment for longer-term sleep problems, you may need to see a specialist. They may prescribe treatment for longer than 13 weeks.
If you've been prescribed melatonin for jet lag, you can take it for a maximum of 5 days.
If you forget to take it
If you forget to take melatonin at your 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.
If you often forget doses, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicines.
If you take too much
If you take 1 or 2 extra melatonin tablets, it's unlikely to harm you.
Urgent advice: Contact 111 for advice now if:
- you've taken more than your prescribed dose of melatonin and feel unwell
Go to 111.nhs.uk or call 111
If you need to go to A&E, 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.