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Melatonin is a hormone naturally produced by the pineal gland in the brain that regulates the sleep-wake cycle.

Last Modified: 09 May 2024

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What is Melatonin? 

Melatonin is a hormone naturally produced by the pineal gland in the brain that regulates the sleep-wake cycle. It is also available as a dietary supplement. 

Melatonin supplements typically contain synthetic or natural melatonin. They may also include additional ingredients such as binders, fillers, or other natural sleep aids like herbs. 

Synthetic melatonin is chemically produced to mimic the natural hormone. Its structure is indole-based, with an acetamide group. 

Global Name

Generic name:  Melatonin (chemical name: N-acetyl-5-methoxytryptatime)
Brand names:  Circadin, Natrol Melatonin, MidNite, Sleepasil



What is Melatonin used for? 

Melatonin is used as a sleep aid, for adjusting the body's internal clock, including accustoming for jet lag, shift work, and certain sleep disorders in both adults and children. 


How do you use Melatonin? 


Melatonin is available in various forms, including tablets, capsules, liquid, and chewables. 

Dosage information: 

  • Adults: 1 to 10 mg, usually taken 30 to 60 minutes before bedtime. 
  • Children: Lower doses are recommended, and usage should be under pediatrician guidance. 


  • Children: Yes, under medical guidance. 
  • Adults: Yes. 
  • Elderlies: Yes, but may require lower doses. 

Is there anyone who can’t take Melatonin? 

  • Adults:  Contraindicated in patients with immune and lymphoproliferative disorders and patients taking immunosuppressants
  • Elderlies: Can use melatonin but may be more sensitive to its effects. 
  • Pregnancy and Lactation: Not enough current studies relating to safety in pregnancy and lactation, please consult a medical professional if considering use during these conditions. 
  • Individuals with allergies to melatonin or any ingredients in the supplement should avoid it. 

Any warnings and precautions : 

Melatonin should not be used as a substitute for good sleep hygiene and may interact with blood thinners, immunosuppressants, diabetes medications, and birth control pills. 


Melatonin can interact with various medications and supplements, so it's important to consult a healthcare provider before use. 

Side Effects

Possible side effects include drowsiness, headache, dizziness, or nausea. 

Pharmacist Tips

  • Understand the Purpose: Melatonin supplements are best used for specific sleep issues, such as jet lag or shift work sleep disorder. It's not a cure-all for all sleep problems, so understanding its purpose is crucial. 
  • Start with Low Doses: Begin with the lowest effective dose to assess your body's response. Higher doses are not necessarily more effective and may cause grogginess the next day. 
  • Timing is Key: Melatonin should be taken 30 to 60 minutes before your intended bedtime. Taking it too early or too late can shift your circadian rhythm in undesired ways. 
  • Maintain Good Sleep Hygiene: Melatonin is not a substitute for good sleep practices. Maintain a regular sleep schedule, create a restful environment, and avoid caffeine and screens before bedtime. 
  • Short-Term Use: Melatonin is generally recommended for short-term use. If you find yourself needing it for an extended period, consult with a healthcare provider. 
  • Check for Drug Interactions: Always check with your pharmacist or doctor if you are taking other medications, as melatonin might interact with them. 
  • Special Populations: Pregnant or nursing women, individuals with autoimmune conditions, and those with epilepsy should consult a healthcare provider before taking melatonin. 
  • Traveling with Melatonin: If you're using melatonin to combat jet lag, start taking it a few days before your trip to adjust your sleep cycle more gradually. 
  • Avoid Alcohol: Do not consume alcohol when using melatonin as it can reduce its effectiveness and increase potential side effects. 
  • Monitor for Side Effects: Be aware of any unusual symptoms such as vivid dreams, morning grogginess, or mood changes, and discuss these with your healthcare provider. 
  • Quality Matters: Purchase melatonin from reputable sources to ensure the product's quality and purity. Check for third-party testing seals for added assurance. 
  • Proper Storage: Keep melatonin in its original packaging, tightly closed, and out of reach of children and pets. Store it in a cool, dry place to maintain its potency. 
  • Consult Before Stopping: If you want to stop taking melatonin after regular use, it's a good idea to consult a healthcare provider, as they may recommend gradually reducing the dose.


Where is Melatonin available in Hong Kong?

Melatonin is an over the counter (OTC) medication that can be sold without a prescription. It is found in all chain drug stores, including Mannings and Watsons. 



Can I become addicted to Melatonin?

Melatonin is not addictive, but it should be used as directed for best results.

Does Melatonin help with insomnia?

Melatonin can help regulate sleep patterns, but it may not be effective for all types of insomnia. 

Is Melatonin available for purchase over the counter?

Yes, Melatonin can be purchased without a prescription in many countries.

How long does Melatonin take to work?

The time it takes for Melatonin to work can vary from person to person. Generally, Melatonin is known for its relatively fast onset of action. Many people experience the effects of Melatonin within 30 minutes to an hour after taking it. 


This website provides content related to drug use and medicine for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Do not use the information on this website to diagnose or treat a health problem or disease without consulting a qualified healthcare provider. The website's owners and contributors are not liable for any repercussions, adverse effects, or consequences resulting from the use of any medication or information provided herein.

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