Melatonin’s most common side effects are headache, dizziness, nausea and next-day drowsiness, and they are usually mild at 0.5 to 3 mg. The bigger risk in India is dose and label accuracy: FSSAI permits up to 10 mg a day, double the highest dose used in the trials that show a benefit.
- What does melatonin actually do in the body?
- What are the side effects of melatonin?
- How well does melatonin actually work for sleep?
- How much melatonin should you take?
- Is it safe to take melatonin every night?
- Do melatonin’s benefits go beyond sleep?
- Why does melatonin content vary so much between products?
- How is melatonin regulated in India?
- Who should avoid melatonin?
- What should you check on a melatonin label?
- The bottom line
- Frequently asked questions
- Sources
What does melatonin actually do in the body?
Melatonin is a hormone the pineal gland releases when light levels drop. It does not sedate the brain the way a sleeping pill does. It signals that the biological night has begun, shifting the body clock so sleep becomes easier to start. That distinction explains most of what follows, including why higher doses do not reliably work better.
Because it is a timing signal rather than a sedative, melatonin performs best for problems of timing: jet lag, shift work, and delayed sleep phase, where a person falls asleep and wakes several hours later than they want to. It performs least well for people who fall asleep easily but wake at 3 am, because that is not a timing problem.
Melatonin is also an antioxidant molecule, and that property is the basis for most of the wider health claims made about it. Whether those laboratory properties translate into measurable health outcomes in people is a separate question, covered further down.
What are the side effects of melatonin?
The side effects reported in short-term trials of melatonin are headache, dizziness, nausea and daytime sleepiness, and they are consistently described as mild. The US National Center for Complementary and Integrative Health notes that short-term use appears safe for most adults, but that long-term safety data is not available.
Two practical points matter more than the list itself. First, daytime grogginess is dose-dependent and is usually a signal that the dose is too high or was taken too late at night, not that melatonin is unsuitable. Second, driving or operating machinery within about five hours of a dose is not advisable while the drowsiness effect is still active.
| Reported effect | What it usually means | Practical response |
|---|---|---|
| Next-day drowsiness | Dose too high, or taken too close to waking time | Lower the dose, take it 1 to 2 hours before bed |
| Headache | Commonly reported, usually transient | Reassess after a few nights; stop if persistent |
| Dizziness | Commonly reported, usually transient | Avoid standing up quickly at night |
| Nausea | Commonly reported, usually transient | Take with a small amount of food |
| Vivid dreams | Frequently described by users, not a formal trial endpoint | Lower the dose if it disturbs sleep |
How well does melatonin actually work for sleep?
It works, but modestly. The most-cited pooled analysis, covering 19 randomised placebo-controlled trials and 1,683 people, found melatonin cut the time taken to fall asleep by an average of 7.06 minutes and increased total sleep time by 8.25 minutes. Sleep quality improved with a standardised mean difference of 0.22, a small effect.
One detail from that analysis is worth knowing before buying. Total sleep time increased only on subjective measures, meaning sleep diaries and questionnaires. When sleep was measured objectively with polysomnography or actigraphy, melatonin did not increase how long people actually slept. It did shorten sleep onset on both objective and subjective measures.
The useful conclusion is that melatonin is a mild, reasonably reliable aid for falling asleep sooner, and a weak one for sleeping longer. The authors also noted that the effect did not fade with continued use, which distinguishes it from several prescription sleep aids.
How much melatonin should you take?
The trials that produced the evidence above used doses of 0.1 mg to 5 mg. FSSAI permits melatonin in nutraceuticals at 2 mg to 10 mg per day. That leaves a gap worth noticing: the legal ceiling in India is twice the highest dose tested in the pooled analysis, and stronger is not the same as better with a hormone that works by timing.
| Reference point | Amount | Source |
|---|---|---|
| Dose range across pooled sleep trials | 0.1 mg to 5 mg | Ferracioli-Oda et al., PLOS ONE, 2013 |
| FSSAI permitted daily range in nutraceuticals | 2 mg to 10 mg per day, maximum | FSSAI Schedule VI, nutraceutical regulations |
| Common Indian retail tablet strengths | 3 mg, 5 mg, 10 mg | Product labels in market |
Timing carries at least as much weight as strength. Melatonin taken one to two hours before the intended bedtime supports the body’s own rising melatonin curve. Taken at 2 am after already lying awake, it can push the body clock later and make the next night harder.
Is it safe to take melatonin every night?
There is no good evidence that nightly melatonin is harmful, and there is no good evidence that it is safe indefinitely either. NCCIH states plainly that the long-term effects of melatonin supplementation are unclear, because the trials that exist were short. Most ran for weeks, and the longest in the pooled analysis ran 182 days.
That is an honest gap, not a hidden danger. It does mean melatonin is better used as a short course to reset a disrupted schedule, after travel or a run of night shifts, than as an indefinite nightly habit. Persistent insomnia lasting more than a few weeks is a reason to see a doctor, not to raise the dose.
Do melatonin’s benefits go beyond sleep?
Melatonin is studied for effects on metabolism, blood pressure, inflammation, immunity and cancer, and the laboratory findings are genuinely interesting. Almost all of it, though, is mechanistic work in cells and animals. Very little has been tested as a health outcome in people, and a molecule that lowers an inflammatory marker in a petri dish has not been shown to prevent disease.
This distinction is where most melatonin marketing goes wrong. Pathway names such as NF-kB, NLRP3 and MAPK/ERK appear in supplement copy because they sound authoritative, but they describe what a cell did in a laboratory, not what happened to a person over years. The table below separates the two.
| Claim made for melatonin | Strongest evidence type | Tested as an outcome in humans? | How settled |
|---|---|---|---|
| Falls asleep faster | Meta-analysis of 19 randomised controlled trials | Yes | Reasonably settled, effect is small |
| Sleeps longer | Same meta-analysis | Yes, but subjective measures only | Weak, not confirmed objectively |
| Improves cholesterol and insulin resistance | Mainly animal and small human studies | Limited | Not established |
| Supports blood pressure and heart function | Mechanistic and animal studies | Limited | Not established |
| Boosts immunity or helps in viral illness | Cell and mechanistic studies | No adequate outcome trials | Not established |
| Protects against cancer | Cell-line and animal studies | No | Not established, do not treat as preventive |
None of this means the wider research is worthless. It means a consumer buying melatonin in 2026 should buy it for sleep timing, judge it on that, and treat every other claim on the pack as unproven until human outcome trials exist.
Why does melatonin content vary so much between products?
Because melatonin is sold as a supplement rather than a drug in most markets, batch-level content testing is not mandatory. When researchers at the University of Guelph analysed 31 melatonin products bought from Canadian shops and pharmacies, the measured melatonin ranged from 83% below to 478% above what the label claimed.
More than 71% of those products fell outside a 10% margin of their stated content. Lot-to-lot variation within a single product reached 465%, meaning two packs of the same item could differ almost fivefold. Separately, 26% of the products contained serotonin, which was not on any label.
Two caveats matter. That study tested Canadian products in 2017, so the exact percentages do not describe the Indian market, and no equivalent published survey of Indian melatonin products exists. What it does establish is that the category has a structural quality-control problem wherever content testing is voluntary, which includes India.
Undeclared serotonin is the finding with real consequences. Anyone taking an SSRI antidepressant, tramadol, or another serotonergic medicine faces a genuine interaction risk from a supplement that is not supposed to contain serotonin at all.
How is melatonin regulated in India?
Melatonin is listed in Schedule VI of FSSAI’s health supplements and nutraceuticals regulations, the schedule covering ingredients permitted as nutraceuticals, with a permitted daily range of 2 mg to 10 mg maximum. That makes it legal to sell over the counter in India as a supplement rather than a prescription medicine.
That classification is not universal. Ireland’s food safety authority, for example, treats melatonin as a prescription-only medicinal product and does not permit it in food supplements at all. A shopper can legally buy a 10 mg tablet over the counter in Mumbai that would need a prescription in Dublin.
The practical consequence for an Indian buyer is that FSSAI sets what may go into the product, but does not test each batch of every brand to confirm the label is accurate. Independent lab verification fills that gap, which is exactly why label accuracy is a core part of how Unbox Health scores lab-tested melatonin supplements sold in India.
Who should avoid melatonin?
Melatonin is a hormone, which places it in a different category from a vitamin. Several groups should not start it without medical advice, and in a few cases should not use it at all. The safety questions are not about acute toxicity, which is low, but about hormonal signalling and drug interactions.
- Anyone on serotonergic medication. SSRIs, SNRIs, tramadol and similar drugs, given the documented finding of undeclared serotonin in supplements.
- Anyone on blood thinners, immunosuppressants, diabetes medication or blood pressure medication. Melatonin has plausible interactions with all four classes and dosing should be discussed with a doctor.
- Pregnant and breastfeeding women. Safety has not been established, and melatonin crosses the placenta.
- Children and adolescents. Use in children should be a paediatrician’s decision, not a parent’s purchase, because the effect on developmental hormone timing is not settled.
- People with autoimmune conditions or epilepsy. Both warrant medical review before starting, given melatonin’s reported effects on immune signalling and seizure threshold.
- Anyone who drives or operates machinery at night. Drowsiness can persist for several hours after a dose.
Insomnia that persists beyond a few weeks, or comes with low mood, breathlessness or loud snoring with pauses, should be assessed by a doctor. Those patterns point to depression, cardiac issues or sleep apnoea, none of which melatonin treats.
What should you check on a melatonin label?
Given that content variance is the category’s main weakness, label reading matters more here than for most supplements. Four checks separate a defensible product from a risky one, and all four can be done in the shop or on the product page before buying.
- Single-ingredient over blends. The Guelph study found herbal-blend formulations were more prone to contamination and label inaccuracy than plain melatonin.
- Stated strength within the FSSAI range. Anything above 10 mg a day is outside what Schedule VI permits.
- Batch-level third-party test data. A GMP claim describes the factory process. A batch certificate of analysis describes what is actually in the pack you are buying.
- Caution with gummies and liquids. These formats add sweeteners and, in published testing, showed greater content variability than tablets.
None of these checks require trusting a brand’s own marketing. They require the brand to publish a number that an independent lab can confirm, which is the standard worth holding the whole category to.
The bottom line
Melatonin’s side effects are mild and manageable at sensible doses. Its benefit for falling asleep is real but small, roughly seven minutes off sleep onset in pooled trials, and its benefit for sleeping longer is weaker than the marketing suggests. The claims about metabolism, immunity and cancer are laboratory findings, not human results.
The risk worth taking seriously is not the hormone. It is buying a pack whose contents do not match its label, in a category where independent content testing is voluntary. Start at the lowest useful dose, take it one to two hours before bed, use it as a short course rather than a permanent habit, and choose a product whose stated strength has actually been verified.
Frequently asked questions
Is it safe to take melatonin every night?
Short-term use appears safe for most adults, but long-term safety has not been established because the trials that exist were short. Melatonin is better used as a short course to reset a disrupted sleep schedule than as an indefinite nightly habit. Insomnia lasting more than a few weeks should be assessed by a doctor.
How much melatonin should an adult take?
The trials showing a benefit used 0.1 mg to 5 mg. FSSAI permits 2 mg to 10 mg a day in nutraceuticals sold in India, which is double the highest tested dose. Starting at the lowest useful strength and taking it one to two hours before bed matters more than choosing a higher number on the pack.
Does melatonin actually help you sleep longer?
Only weakly. A pooled analysis of 19 randomised trials found total sleep time rose by about 8 minutes, but that increase appeared only on sleep diaries and questionnaires. When sleep was measured objectively with polysomnography or actigraphy, melatonin did not increase how long people slept. It did reliably shorten the time taken to fall asleep.
Can you buy melatonin without a prescription in India?
Yes. Melatonin is listed in Schedule VI of FSSAI's health supplements and nutraceuticals regulations, so it is sold over the counter as a supplement rather than a prescription medicine. That classification is not universal: Ireland, for example, treats melatonin as a prescription-only medicinal product and does not permit it in food supplements.
Does melatonin interact with other medicines?
It can. Blood thinners, immunosuppressants, diabetes medication and blood pressure medication all warrant a doctor's advice first. Anyone taking an SSRI, SNRI or tramadol should be especially careful, because published testing found undeclared serotonin in about a quarter of melatonin supplements analysed, which creates a real interaction risk.
Are melatonin gummies as reliable as tablets?
Published testing found gummies and liquid formats showed greater content variability than plain tablets, and they add sweeteners with no sleep benefit. Herbal-blend formulations were also more prone to contamination and label inaccuracy than single-ingredient melatonin. A plain tablet with batch-level third-party test data is the more defensible choice.
Do melatonin's benefits go beyond sleep?
Melatonin is studied for effects on metabolism, blood pressure, inflammation, immunity and cancer, but almost all of that work is in cells and animals. None of those claims has been established as a health outcome in human trials. Melatonin is worth buying for sleep timing; every other claim on the pack should be treated as unproven.
Sources
- Ferracioli-Oda, E., Qawasmi, A. & Bloch, M. H. (2013). Meta-analysis: Melatonin for the treatment of primary sleep disorders. PLOS ONE, 8(5), e63773. https://doi.org/10.1371/journal.pone.0063773
- Erland, L. A. E. & Saxena, P. K. (2017). Melatonin natural health products and supplements: presence of serotonin and significant variability of melatonin content. Journal of Clinical Sleep Medicine, 13(2), 275 to 281. https://doi.org/10.5664/jcsm.6462
- National Center for Complementary and Integrative Health, National Institutes of Health. Melatonin: What You Need To Know. https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know
- Food Safety and Standards Authority of India. Food Safety and Standards (Health Supplements, Nutraceuticals, Food for Special Dietary Use, Food for Special Medical Purpose, Functional Food and Novel Food) Regulations, Schedule VI: list of ingredients as nutraceuticals. FSSAI implementation document
- Food Safety Authority of Ireland. Medicinal product (melatonin) not permitted in food products. https://www.fsai.ie/news-and-alerts/food-alerts/melatonin-permitted-under-prescription-only-presen
Reviewed by: Mruga Dholakia, Food Scientist & Nutritionist | Last updated: July 2026
