Melatonin (Circadin brand) is used for short-term treatment of insomnia (difficulty sleeping). Learn how to use the medication, its common side effects, special precautions to watch out for, and more.

What is this medication for?

Melatonin is used for short-term treatment of insomnia (difficulty sleeping).

It may also be used for other conditions. Check with your healthcare professional if you are unsure why you are given this medication.

How should I take or use this medication?

• Follow the instructions on your medication label and take this medication as prescribed by your doctor. 
• This medication should be taken with or after food.
• This medication should be taken shortly (1 – 2 hours) before going to bed.
• The prolonged-release (PR) tablet must be swallowed whole with water or other liquids; do not crush or chew the tablet. 

What should I do if I forget to take or use this medication?

• If you forget to take a dose, skip the missed dose and take the next dose at your usual timing. This medication is usually taken on an as needed basis to help you sleep. 
• For example, for a medication to be taken at 8pm and you missed your dose, take it before the next time you are going to sleep if needed. Do not take two doses to make up for the missed dose.

What precautions should I take when taking or using this medication?

Inform your healthcare professional if: 

• You are allergic to this medication or any of the other ingredients of this medication
• You are pregnant, planning to become pregnant, or breastfeeding. If you are pregnant and/or breastfeeding, your doctor would have discussed the potential benefits and side-effects with you. If you have further questions or concerns, do consult your doctor.
• You are taking any other medications including over-the-counter medications, supplements,  traditional medications and herbal remedies. Some of them may affect how this medication works or cause serious drug interactions.
• You are smoking. Smoking may decrease the amount of Melatonin that stays in your body.
• You have or have ever had:
  • Other drug allergies or lactose intolerance (congenital galactosaemia, glucose-galactose malabsorption syndrome or lactase deficiency)
  • Medical conditions such as:
    • Lung, liver or kidney disease
    • Drug or alcohol abuse
    • Any autoimmune disease (where the body is ‘attacked’ by its own immune system)

What are some common side effects of this medication?

• Nausea or vomiting
  • Take the medication with or after food
  • Take small but frequent meals, and avoid fatty or spicy food
• Dizziness
  • Get up slowly from a sitting or lying down position
• Drowsiness or feeling tired
  • Avoid driving or taking part in activities that require concentration
  • Discuss with your doctor if you can take your medication at a different time of the day
• Feeling clumsy or unsteady 
• Headache

Most of the side effects listed here will improve with time. Speak with your doctor if any of them continues, worsens or affects your daily life.

What are some rare but serious side-effects that I need to seek medical advice immediately?

The symptoms of a drug allergy include one or more of the following: 

• Swollen face/eyes/lips/tongue
• Difficulty in breathing
• Itchy skin rashes over your whole body

Rarely this medication may cause:

• Severe chest pain
• Very fast heartbeat
• Memory loss (amnesia)
• Abnormal thinking or changes in behaviour
• Unusual excitement, nervousness, irritability, or agitation 
• Blurred vision
• Fainting episodes

If you experience any of these side effects, you should stop your medication and inform your healthcare professional immediately.

What food or medication should I avoid when I take or use this medication?

Avoid drinking alcohol while taking Melatonin as it can cause excessive sleepiness.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children. 

How do I throw away this medication safely?

Pack this medication into a trash bag and seal it tightly before throwing into the rubbish chute or bin.

What else should I know about this medication?

The information above refers to Melatonin prolonged release (PR) tablets (Circadin®) that require a doctor’s prescription. For information on Melatonin purchased over the counter, please refer to the individual product labeling.

Disclaimer

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Feb 2025