Melatonin for Jet Lag: Does It Work, How to Take It & UK Prescription Guide
What the evidence says about melatonin for jet lag, how to take it under the UK licence, side effects and how to get it legally.
Part of our jet lag guide.
Key fact: in the UK, melatonin 3mg is licensed for the short-term treatment of jet lag in adults: one tablet at bedtime after you arrive, for up to 5 days.
Planning a long-haul trip?
A confidential online consultation with a UK-registered prescriber can help determine whether melatonin is appropriate for your travel plans. Approved before 3pm, Monday to Friday? Dispatched the same day. Prescriptions are issued by pharmacist independent prescribers after an online assessment; completing a consultation doesn’t guarantee treatment.
Start Jet Lag Consultation →Jet lag affects almost everyone who crosses three or more time zones. Whether you're travelling eastward to Dubai or westward to New York, that familiar mix of exhaustion, disturbed sleep and brain fog can linger for days. Melatonin for jet lag has become one of the most widely discussed remedies, and for good reason. It's a hormone your body already produces, and it plays a central role in regulating your sleep-wake cycle.
This guide explains what the evidence actually says, the correct dose and timing, potential side effects, and how to access melatonin legally and safely in the UK through a regulated online pharmacy service.
What Is Jet Lag?
Jet lag, medically known as desynchronosis, is a temporary sleep disorder that occurs when your body's internal clock (circadian rhythm) is out of sync with the local time at your destination. It's caused by rapid travel across multiple time zones, most commonly three or more. Our main jet lag guide covers the causes and symptoms in more detail.
Common Symptoms of Jet Lag
Symptoms usually appear within one to two days of arrival and can include:
- Difficulty falling or staying asleep at the appropriate local time
- Daytime sleepiness and fatigue
- Difficulty concentrating or "brain fog"
- Irritability or low mood
- Stomach upset, including nausea or changes in appetite
- A general feeling of being unwell
According to the NHS, most people recover from jet lag within a few days, though symptoms can last up to a week depending on how many time zones were crossed and the direction of travel. See how long jet lag lasts.
What Is Melatonin and How Does It Help with Jet Lag?
Melatonin is a naturally occurring hormone produced by the pineal gland, a small structure deep in the brain. It's sometimes called the "hormone of darkness" because its release is triggered by falling light levels, typically beginning two to three hours before your usual bedtime and peaking between 2am and 4am.
Its primary role is to signal to the brain and body that it is time to prepare for sleep. It does not work like a sedative or sleeping tablet. Instead, it gently shifts your circadian rhythm, essentially adjusting your body clock, to align with a new time zone.
How melatonin helps: melatonin can shift the timing of your internal body clock, making it an effective tool for overcoming jet lag when taken at the correct time. It tells the brain it is night-time, helping you fall asleep at the right local hour and reset your circadian rhythm more quickly.
Why Timing Matters More Than Dose
Unlike most medicines, melatonin's effectiveness for jet lag depends heavily on when you take it, not just how much you take. Under the UK licence, it's taken at bedtime in your new time zone, never in the morning. Taking it at the wrong time can shift your body clock the wrong way and make jet lag worse rather than better.
What the Evidence Actually Says
The evidence for melatonin in jet lag is generally supportive, though there are important nuances to understand.
A landmark Cochrane systematic review by Herxheimer and Petrie (2002) found that melatonin was remarkably effective at reducing jet lag when taken at the correct time at the destination. The review concluded it was well tolerated and more effective than placebo for preventing and reducing jet lag symptoms, particularly after eastward flights crossing five or more time zones.
Important nuance: some more recent analyses have produced mixed findings, particularly on how quickly people fall asleep. Melatonin works best when taken at the right time relative to your destination's bedtime. Taken at the wrong point in your circadian cycle, it may have little benefit, or could shift your clock in the wrong direction.
In the UK, melatonin is licensed specifically for the short-term treatment of jet lag in adults when taken as an immediate-release (standard) tablet. Our melatonin 3mg tablets for jet lag are a prescription-only medicine, not available over the counter, and must be obtained via a regulated prescriber.
| Treatment approach | Evidence for jet lag | Available over the counter in the UK? |
|---|---|---|
| Melatonin (prescription) | Good evidence: the Cochrane review supports it when timed correctly | No: prescription required |
| Light exposure | Good evidence: the most powerful body clock reset signal | Yes (natural daylight) |
| Sleep routine adjustments | Moderate: helpful alongside other measures | Yes (no cost) |
| Herbal supplements (valerian, etc.) | Limited or insufficient evidence | Yes, but the evidence is weak |
| Prescription sedatives and sleeping tablets | Promote sleep but don't reset the body clock | No: prescription required |
How to Take Melatonin for Jet Lag: Dose and Timing by Direction
The standard UK dose for jet lag is a 3mg immediate-release melatonin tablet, taken once daily for up to five days. According to the product's licence, you should take your first dose at your normal bedtime once you arrive at your destination, but not before 8pm or after 4am local time.
The licensed dose is the same whichever way you fly: one 3mg tablet at bedtime after you arrive, for up to 5 days. Your prescriber may increase this to 6mg if needed.
Step-by-Step Guidance
- Begin taking melatonin on the day you arrive at your destination.
- Take one 3mg standard-release tablet at your normal bedtime in the new time zone, ideally between 10pm and 11pm local time.
- Do not take it before 8pm or after 4am local destination time.
- Continue for up to five nights: this is enough for most journeys.
- If you forget a dose, skip it and resume the following night. Never double up.
- Do not drive or operate machinery after taking melatonin.
Eastward vs westward travel: eastward travel (for example, UK to South-East Asia) causes the most disruption, as it requires you to fall asleep earlier than your body expects. Melatonin taken in the evening helps advance your sleep phase. Westward travel tends to be better tolerated, though melatonin may still help if crossing many time zones. Read more in our guide to east vs west jet lag.
Who Should Not Take Melatonin?
Melatonin for jet lag is licensed for adults. It is not recommended for children for this use. You should discuss its use carefully with your prescriber if you:
- Are pregnant or breastfeeding
- Could get pregnant and aren't using contraception
- Have significant liver disease (hepatic impairment)
- Have an autoimmune condition
- Are taking anticoagulants (warfarin), anticonvulsants or other medicines affecting liver enzymes
Not sure if melatonin is right for your trip?
If you're unsure whether melatonin is suitable for your travel plans, an online consultation allows a qualified prescriber to review your circumstances and advise accordingly. Approved before 3pm, Monday to Friday? Dispatched the same day. Prescriptions are issued by pharmacist independent prescribers after an online assessment; completing a consultation doesn’t guarantee treatment.
Start Jet Lag Consultation →Side Effects and Safety Considerations
Melatonin is generally considered safe for short-term use in healthy adults. Reported side effects, while uncommon, can include:
- Drowsiness or sedation the following morning
- Headache
- Dizziness
- Nausea
- Restlessness
- Skin reactions (rare)
Do not drive after taking melatonin: melatonin can cause drowsiness. Don't drive, operate heavy machinery or do any safety-critical task within several hours of taking your dose. This is especially important in unfamiliar surroundings.
There is no evidence that melatonin causes dependence, rebound insomnia or tolerance at the doses used for jet lag. However, for jet lag specifically, treatment should not exceed five days. Longer-term use is a separate clinical matter and needs specialist oversight.
Non-Medication Tips to Help You Recover Faster
Melatonin works best as part of a broader approach to jet lag recovery. Sleep habits and daylight are essential, and for mild jet lag they may be enough on their own. Our guide on how to get over jet lag covers them in detail, and how to prevent jet lag explains what to do before you fly.
Light Exposure: Your Most Powerful Tool
Light is the strongest cue for resetting your body clock. Morning light at your destination signals to your brain that it is daytime, speeding up adjustment. After eastward travel, seek bright sunlight in the morning. After westward travel, afternoon or evening light is more helpful.
Further Practical Strategies
- Adjust your sleep and meal schedule to your destination time as soon as possible after arrival.
- Stay hydrated throughout your flight: cabin humidity is low and dehydration can worsen symptoms.
- Avoid alcohol and caffeine during the flight and in the first day or two after landing.
- Spend time outdoors in natural light at your destination: even a short walk helps.
- Avoid long naps during local daytime hours; short naps of 20 minutes are better if you are very tired.
- Set your watch and devices to local time as soon as you board.
When to Seek Medical Help
Jet lag is generally self-limiting and settles within a week. However, there are situations where you should get prompt medical advice.
Call 999 if you have chest pain, sudden shortness of breath or cough up blood during or shortly after your flight: these can be signs of a blood clot in the lungs (pulmonary embolism). Get urgent help for a painful, swollen calf or thigh (possible deep vein thrombosis), or for extreme confusion beyond normal travel tiredness.
If sleep disturbance or fatigue persists for more than two to three weeks after returning home, speak to your GP. Persistent symptoms may point to a sleep problem unrelated to travel.
UK safety and reporting side effects
In the UK, melatonin is a prescription-only medicine. Melatonin 3mg tablets are licensed for the short-term treatment of jet lag in adults aged 18 and over, and they aren't licensed for jet lag in children. Before any medicine is supplied, a GPhC-registered pharmacist independent prescriber reviews your consultation, including your health and the other medicines you take. Always read the patient information leaflet in the pack.
Melatonin sold as a supplement abroad or on unregulated websites (as gummies, sprays or tablets) isn't a licensed medicine in the UK, and its strength and contents can vary. Only buy medicines from a registered UK pharmacy: you can check any online pharmacy on the GPhC register. Our guide can you buy melatonin over the counter? explains the UK rules.
If you think you've had a side effect from a medicine, tell your pharmacist or doctor. You can also report it to the MHRA through the Yellow Card scheme.
Jet Lag and Travel Health from Access Doctor
Treatment option
Melatonin for Jet Lag
UK-licensed prescription melatonin for adults, issued by pharmacist independent prescribers after an online consultation. Up to 5 days’ treatment.
Learn more →Travel health
Travel Health Treatments
Going further afield? Our travel health service covers malaria tablets, travel sickness and jet lag, from regulated prescribers. We don’t provide vaccinations.
View travel health →Concerned about jet lag on your next trip?
A confidential online consultation allows a UK-registered prescriber to review your circumstances and decide on the most appropriate approach. Approved before 3pm, Monday to Friday? Dispatched the same day. Prescriptions are issued by pharmacist independent prescribers after an online assessment; completing a consultation doesn’t guarantee treatment.
Start Jet Lag Consultation →Frequently Asked Questions
Can I buy melatonin over the counter in the UK for jet lag?
No. Unlike in some other countries, melatonin is a prescription-only medicine in the UK. You can't legally buy it over the counter in a pharmacy or health food shop. You need a regulated prescriber, such as Access Doctor's online consultation service, or your GP.
What is the correct melatonin dose for jet lag?
The standard dose for jet lag in adults is 3mg of immediate-release melatonin, taken once daily. Take it at your normal bedtime in the new time zone, not before 8pm or after 4am local time, and continue for up to five nights. Always follow the guidance from your prescriber.
Does melatonin make you sleep immediately?
No. Melatonin is not a sedative and doesn't cause immediate sleep, although it can make you drowsy. It works by adjusting your body's internal clock, shifting the timing of your sleep to match the local time zone. It helps your brain recognise that it is night-time, but it doesn't knock you out like a sleeping tablet.
Is it safe to take melatonin every night during a holiday?
For jet lag, melatonin should be taken for a maximum of five days. It isn't intended for ongoing nightly use in this context. If you have persistent sleep difficulties unrelated to travel, speak to your GP, as this may need a different assessment and plan.
Can I take melatonin if I'm pregnant or breastfeeding?
Melatonin isn't recommended during pregnancy or breastfeeding because of limited safety data, and we don't supply it if you're pregnant, breastfeeding, trying to conceive, or could get pregnant and aren't using contraception. Speak to your GP or midwife about other ways to manage jet lag.
Can I drink alcohol while taking melatonin?
It's best not to. Alcohol can interfere with sleep quality and may increase the drowsiness caused by melatonin. It can also disrupt your body clock, potentially making jet lag worse. Avoid alcohol while taking melatonin and during the first few days of travel.
Can I take melatonin on a short-haul flight within Europe?
Jet lag is rarely a significant problem after short-haul European flights, as fewer time zones are crossed. Melatonin is most useful when you're crossing three or more time zones. For shorter journeys, adjusting your sleep schedule and getting morning light are usually enough.
Does the direction of travel affect how well melatonin works?
Yes. Eastward travel (for example, UK to Japan or Australia) tends to cause more severe jet lag and generally responds better to melatonin taken in the evening at your destination. Westward travel (for example, UK to the USA) is usually easier to adjust to, though melatonin can still help if many time zones are crossed. The timing of your dose is the most important factor.
How long does melatonin take to work for jet lag?
Melatonin typically starts working within 30 to 60 minutes of taking it. However, its main effect is gradual body clock adjustment rather than immediate sleep. Most people notice improvement within one to two days, with the full benefit after three to five days of taking it at the correct time.
What happens if I take melatonin at the wrong time?
Taking melatonin at the wrong time can shift your body clock in the opposite direction, potentially making jet lag worse. For example, taking it in the morning after eastward travel may delay your body clock further. Always follow your prescriber's timing guidance.
References
- Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database of Systematic Reviews. 2002. doi.org/10.1002/14651858.CD001520
- Melatonin 3mg film-coated tablets: summary of product characteristics. medicines.org.uk
- NHS. Melatonin: how and when to take it. nhs.uk
- NHS. Jet lag. nhs.uk
- Centers for Disease Control and Prevention. CDC Yellow Book: Jet lag disorder. cdc.gov
- Arendt J. Approaches to the pharmacological management of jet lag. Drugs. 2018;78:1419–31. doi.org/10.1007/s40265-018-0973-8
- British National Formulary (BNF). Melatonin. bnf.nice.org.uk
Medical disclaimer: This article has been written for information only and isn’t medical advice. It isn’t a substitute for a consultation with a qualified healthcare professional. All prescriptions are issued by pharmacist independent prescribers following an online clinical assessment, and completing a consultation doesn’t guarantee that a prescription will be issued. If you have concerns about your health, consult your GP or call NHS 111. In an emergency, call 999.