Sleep · Medication Guide
Melatonin in Thailand
What melatonin actually does, how well it works for sleep and jet lag, its side effects, and why getting it in Thailand is not as simple as it is abroad. Reviewed by a licensed physician at a MOPH-registered men's health clinic.
- Take 30–60 min before bed
- Regulated as a medicine in Thailand
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Medically reviewed by Dr. Noppon Arunkajohnsak (Win)
Menscape Clinic
Last reviewed
11 July 2026
20–50 min
Short half-life
immediate-release clears the body fast
30–60
Minutes before bed
the timing that matters most
~7 min
Faster to fall asleep
average across pooled sleep trials
5+
Time zones for jet lag
where the evidence is strongest, flying east
Key takeaways
Melatonin is a hormone that signals night to your body clock, so it is best at fixing timing problems (jet lag, shift work, delayed sleep) rather than sedating you like a sleeping pill.
In pooled trials it helps people fall asleep about 7 minutes faster and sleep a little longer: a real but modest effect, not a knock-out pill.
In Thailand melatonin is regulated as a medicine, not a dietary supplement, so it is not sold freely on shelves the way it is in the US. It comes through pharmacies or on a doctor's advice.
It is not habit-forming, but a doctor should check your other medicines and conditions first, especially blood thinners, diabetes and blood-pressure drugs.
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What melatonin is & how it works
Melatonin is a hormone your pineal gland releases when it gets dark, telling your brain it is night and time to wind down. As a medicine, it is a synthetic copy of that same hormone, used mainly to reset a sleep-wake cycle that has drifted out of sync.
It is not a sedative. Rather than switching off the brain the way sleeping pills do, melatonin nudges your internal clock. It binds to MT1 and MT2 receptors in the suprachiasmatic nucleus, the master clock in the brain, shifting the timing of when you feel sleepy. That is why it shines for jet lag, shift work and delayed sleep phase, and is less impressive for classic "I just can't sleep" insomnia.
Timing and dose matter more than size. Taken 30–60 minutes before your target bedtime, a low dose is often as effective as a high one. Because it is short-acting, it helps you fall asleep but does not keep you unconscious all night.
Darkness triggers release
Normally your pineal gland releases melatonin as light fades, signalling night to the brain.
It reaches the body clock
Melatonin binds MT1 and MT2 receptors in the brain's master clock, the suprachiasmatic nucleus.¹
The clock shifts
This moves the timing of your sleep-wake cycle, so you start to feel sleepy earlier.
You fall asleep sooner
Taken 30–60 minutes before bed, it shortens the time to fall asleep and helps realign a disrupted rhythm.¹
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Getting melatonin in Thailand
Thai FDA status
Here is the surprise for many expats: Thailand regulates melatonin as a medicine, not a dietary supplement. Unlike the US, where it sits on supermarket shelves, it cannot be sold as a general supplement here and is handled through licensed pharmacy channels.⁵
How to get it through Menscape
Menscape does not keep melatonin as a shelf product. After a short check with a doctor or pharmacist, it can be ordered in for you as a pharmacy-channel medicine, sold in Thailand under brands such as Circadin (prolonged-release melatonin). That check confirms it suits your situation and won't clash with your other medicines.
Safety vs the grey market
Because it is a regulated medicine here, avoid grey-market "supplement" melatonin bought online or carried in bulk. Products from unlicensed sellers vary widely in actual dose and purity, and nobody is accountable for what you receive.
Thai FDA. Melatonin is regulated as a modern medicine in Thailand and is not approved for sale as a dietary supplement; it should be obtained through licensed pharmacy or medical channels.⁵
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Does it work? The evidence
Melatonin has a well-replicated effect on sleep timing and a modest one on sleep itself. A meta-analysis of 19 randomised trials (1,683 people) found it helped people fall asleep about 7 minutes faster, sleep roughly 8 minutes longer, and rate their sleep quality higher.² Real, but nobody should expect a sledgehammer.
Where it is genuinely strong is jet lag. A Cochrane review concluded melatonin is remarkably effective at preventing or reducing jet lag when crossing five or more time zones, particularly flying east, taken close to the destination bedtime.³ It also helps in shift work and delayed sleep phase, where the problem is timing rather than an inability to sleep at all.
~7 min
Faster to fall asleep
pooled across 19 trials (1,683 people)
5+
Time zones for jet lag
where Cochrane found the clearest benefit
From the Ferracioli-Oda et al. (2013) meta-analysis and the Cochrane jet-lag review. Individual results vary.
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Side effects & who shouldn't take it
Common side effects
Melatonin is well tolerated. The most common effects are next-day grogginess or drowsiness, headache, dizziness and nausea. Some people report unusually vivid dreams. These are usually mild and settle when the dose is lowered or the timing adjusted.⁷
Worth knowing
Because it can cause drowsiness, do not drive or operate machinery after taking it. It may mildly affect blood sugar and blood pressure, and occasional mood or irritability changes are reported, so mention any mood disorder to your doctor.
Not suitable for
Pregnant or breastfeeding women, and children, should only use it under direct medical supervision because long-term data are limited. People with an autoimmune condition or a seizure disorder should check with a doctor first.
Interactions to flag
Tell your doctor if you take blood thinners (such as warfarin), diabetes or blood-pressure medicines, other sedatives, or fluvoxamine, which can sharply raise melatonin levels. Do not combine melatonin with alcohol.
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Alternatives & combinations
Behavioural · first-line
Sleep hygiene & CBT-I
For ongoing insomnia, cognitive behavioural therapy for insomnia (CBT-I) and consistent sleep habits are the recommended first-line treatment, with longer-lasting results than any pill.⁶
Circadian · pairs well
Timed light exposure
Bright light in the morning and dim screens at night help reset the body clock. It is often combined with melatonin, especially for jet lag and shift work.
Prescription · doctor-decided
Short-term sleep medicines
For some kinds of insomnia a doctor may consider a short course of a prescription sleep aid. These can work faster but carry dependence and next-day risks that melatonin does not.
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Online chat or walk-in
Start online or drop into the clinic at Asoke. Tell us about your sleep problem, your travel or shift pattern, and any current medicines.
Doctor or pharmacist check
A licensed Thai doctor or pharmacist confirms melatonin is a sensible fit and screens for interactions and conditions that would make it unsuitable.
Ordered in for you
Because it is not a shelf product, the medicine is ordered through licensed pharmacy channels for pickup or delivery once your check is done.
Aftercare advice
You get clear guidance on dose and timing, including how to time it for jet lag, and can check back in if your sleep does not improve.
The doctor or pharmacist decides. A check is not a purchase and does not guarantee melatonin is right for you. If it is not, they will explain why and suggest better options.
Medically reviewed by
Dr. Noppon Arunkajohnsak (Win)
Menscape Clinic, Bangkok
“Most people reach for melatonin as a sleeping pill and are disappointed. It is a body-clock signal, and used at the right time and dose it can be genuinely useful for jet lag and shifted sleep. That is exactly what the consultation is there to work out.”
- Reviewed
- 11 July 2026
- Next review
- January 2027
- Editorial standard
- Each guide is checked against the Thai FDA label and the primary literature, then reviewed by a licensed physician.
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Frequently asked questions
Can I buy melatonin over the counter in Thailand?
Not the way you can abroad. Thailand regulates melatonin as a medicine, not a dietary supplement, so it is dispensed through pharmacies or on a doctor's advice rather than sold freely on supermarket shelves. Bringing it in from another country in bulk can also cause problems at customs.
Is melatonin addictive?
No. Unlike many prescription sleep drugs, melatonin is not habit-forming and does not cause dependence or withdrawal. That is one of its main advantages, though it also means the effect is gentler.
Does it actually work for insomnia?
The effect is modest for classic insomnia: pooled trials show people fall asleep about 7 minutes faster on average. It works best when the real problem is timing, such as jet lag, shift work or a delayed body clock, rather than an inability to sleep at all.
When and how much should I take?
It is usually taken 30–60 minutes before your target bedtime, and a low dose often works as well as a high one. The right amount and timing depend on whether you are treating jet lag, shift work or sleep onset, which is what the consultation sorts out.
How do I use it for jet lag?
For jet lag the timing depends on which direction you flew and how many time zones you crossed. A Cochrane review found melatonin most effective crossing five or more time zones, especially flying east, taken near the destination bedtime. A doctor can map it to your specific trip.
Can I bring my own melatonin into Thailand?
Small amounts for personal use are generally tolerated, but because it is a regulated medicine here, carry it in its original packaging and do not bring large quantities or anything for resale. If you rely on it, it is safer to arrange a legitimate local supply.
Is it safe to take every night, long-term?
Short-term use is well studied and generally safe. Long-term data are more limited, so it is best used for a defined purpose and reviewed with a doctor, particularly if you have other conditions or take other medicines.
Can I take it with alcohol or other sleep medicines?
Avoid alcohol, which worsens sleep quality and adds to drowsiness, and be cautious combining it with other sedatives. Also tell your doctor about blood thinners, diabetes and blood-pressure medicines, and fluvoxamine, which can all interact with melatonin.
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References
1. Zisapel N. New perspectives on the role of melatonin in human sleep, circadian rhythms and their regulation. Br J Pharmacol. 2018;175(16):3190-3199.
2. Ferracioli-Oda E, Qawasmi A, Bloch MH. Meta-analysis: melatonin for the treatment of primary sleep disorders. PLoS One. 2013;8(5):e63773.
3. Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev. 2002;(2):CD001520.
4. European Medicines Agency. Circadin (prolonged-release melatonin 2 mg) summary of product characteristics. Updated 2020.
5. Thai Food and Drug Administration. Drug registration database. ndi.fda.moph.go.th. Accessed July 2026.
6. Sateia MJ, et al. Clinical practice guideline for the pharmacologic treatment of chronic insomnia in adults. American Academy of Sleep Medicine. J Clin Sleep Med. 2017;13(2):307-349.
7. Andersen LPH, Gögenur I, Rosenberg J, Reiter RJ. The safety of melatonin in humans. Clin Drug Investig. 2016;36(3):169-175.
This guide is educational information, not medical advice. In Thailand melatonin is a regulated medicine that should be used on the advice of a licensed doctor or pharmacist, especially alongside other medications.
This guide is part of the Menscape sleep library
Book a consultationCan't sleep or jet-lagged? Ask a doctor, not the supplement aisle.
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