For most adults, 1 to 5 mg of melatonin is considered safe for short-term use, with many sleep experts recommending you start at the lowest effective dose. That often means beginning with just 0.5 to 1 mg and increasing only if needed. Higher doses are not necessarily more effective, and the “right” amount varies significantly by age, body size, and what you’re using it for.
Starting Doses for Adults
The NHS prescribes 2 mg slow-release tablets as the standard dose for adults with short-term insomnia, taken one to two hours before bed. For longer-term sleep problems, the same 2 mg starting dose applies, with a maximum of 10 mg daily. For jet lag, 3 mg is typical, with up to 6 mg if needed.
These numbers may seem modest compared to the 5 mg and 10 mg tablets lining store shelves, but your body produces only about 0.1 to 0.3 mg of melatonin naturally each evening. Supplemental doses of even 1 mg raise blood levels well above what your brain would produce on its own. Starting low gives you the benefits of the hormone’s sleep-timing signal without flooding your system unnecessarily.
Why More Isn’t Better
Melatonin has a short half-life of roughly 35 to 40 minutes, meaning your body clears it quickly. Taking a large dose doesn’t extend its effects proportionally. Instead, it spikes your blood concentration far beyond normal levels, which can cause next-day grogginess, headaches, dizziness, and nausea. Some people also report vivid dreams or mild stomach discomfort at higher doses.
One advantage melatonin has over many sleep aids: you’re unlikely to become dependent on it or need increasing amounts over time to get the same effect. That said, the long-term safety of nightly use beyond a few months still lacks strong evidence.
Doses for Children
Children respond to much smaller amounts. The American Academy of Pediatrics recommends starting at 0.5 to 1 mg, taken 30 to 90 minutes before bedtime. Most children who benefit from melatonin, including those with ADHD, don’t need more than 3 to 6 mg. The most common side effects in kids are morning sleepiness, bedwetting, and headache.
There are real safety concerns worth knowing about. Between 2012 and 2021, more than 260,000 child poisoning reports in the U.S. involved melatonin, and roughly 1% of those children required hospitalization. The risk isn’t that melatonin is highly toxic. It’s that bottles of gummy melatonin look and taste like candy, making accidental overconsumption easy. Longer-term concerns also exist: researchers don’t yet know how sustained melatonin use might affect growth and development, particularly around puberty.
Lower Doses for Older Adults
Adults over 65 process melatonin differently. Peak blood concentrations after the same oral dose can be up to 240% higher in older adults compared to people under 45. That means a 5 mg tablet could produce wildly unpredictable effects in someone over 65. The European Food Safety Authority recommends a maximum of 1 mg for this group, while the American Academy of Sleep Medicine suggests a ceiling of 2 mg.
Drug interactions also become a bigger concern with age. Melatonin can intensify the effects of blood pressure medications, sometimes causing unpredictable drops. It can increase bleeding risk when combined with blood thinners like warfarin. It adds to the sedative effect of other central nervous system depressants, raising fall risk. And it may interfere with anticonvulsant and diabetes medications. If you take any of these, the dose question matters more than usual, because even a small amount of melatonin can shift how your other medications behave.
What’s Actually in the Bottle
One of the biggest safety issues with melatonin has nothing to do with the dose you choose. It’s whether the dose on the label matches what’s inside. A study analyzing 31 melatonin supplements found that more than 71% contained amounts that didn’t match the label within a 10% margin. The actual melatonin content ranged from 83% less to 478% more than what was declared. Lot-to-lot variability within a single product varied by as much as 465%. And 26% of the supplements tested contained serotonin, a compound with much more significant physiological effects that wasn’t listed on the label at all.
This happens because melatonin is classified as a dietary supplement in the U.S., not a medication, so it doesn’t undergo the same manufacturing quality controls. Choosing products that carry a third-party testing seal (like USP or NSF International) offers some additional assurance that what’s on the label is what’s in the pill.
Practical Guidelines by Group
- Healthy adults: Start at 0.5 to 1 mg. Most people do well at 1 to 3 mg. The upper limit for longer-term use is typically 10 mg, but few people need anywhere near that.
- Children: Begin at 0.5 mg. Stay under 3 to 6 mg. Keep bottles out of reach.
- Adults over 65: Start at 0.5 mg and stay at or below 1 to 2 mg. Be especially cautious with other medications.
- Jet lag: 3 mg taken at your destination’s bedtime, up to 6 mg if needed, for a few days.
Timing matters as much as dose. Taking melatonin too early or too late can shift your sleep cycle in the wrong direction. For general insomnia, 30 minutes to two hours before your target bedtime is the standard window. Slow-release formulations help if you tend to wake in the middle of the night, while standard tablets work better for people who mainly struggle to fall asleep.