Most sleep experts consider 10 mg per day the upper limit for melatonin in adults, though effective doses are usually much lower. There’s no officially regulated maximum because melatonin is sold as a dietary supplement in the United States, not a prescription drug, so the FDA doesn’t set dosage limits. That means the ceiling you’ll find on store shelves can vary wildly, and “more” doesn’t mean “better” when it comes to this hormone.
Why There’s No Official Maximum
In the U.S., melatonin is classified as a dietary supplement rather than a medication. The FDA doesn’t regulate it the way it would a prescription sleep aid, which means no government agency has established a formal maximum dose. Manufacturers can sell it in strengths ranging from 0.5 mg to 20 mg or higher without any required cap.
In the UK, melatonin is available by prescription. The NHS sets a maximum of 10 mg once daily for adults with longer-term insomnia, taken as slow-release tablets. The European Food Safety Authority takes a more conservative stance, recommending no more than 0.3 to 1 mg for reducing the time it takes to fall asleep. These differences reflect genuine disagreement about where the sweet spot lies.
What Most Experts Recommend for Adults
The general guidance from sleep researchers is that adults should stay between 1 and 5 mg per day and not exceed 10 mg. That 10 mg figure comes up consistently as the point beyond which side effects increase without meaningful improvement in sleep. A systematic review of studies in older adults found that doses ranging from 0.5 to 6 mg significantly improved sleep compared to placebo, while doses above 6 mg showed no additional benefit.
That last finding is important: taking more melatonin can actually backfire. High doses flood melatonin receptors in the brain with far more of the hormone than the body normally produces, which can cause those receptors to become less responsive over time. The result is that large doses may worsen insomnia rather than relieve it. Your body’s natural melatonin production at night peaks at levels equivalent to roughly 0.3 mg, so even a standard 5 mg tablet delivers many times the natural amount.
Melatonin also clears the body quickly. Its half-life is only about 35 to 40 minutes, meaning most of it is gone within a few hours. This is why slow-release formulations exist for people who fall asleep fine but wake up in the middle of the night.
Doses for Children
Children are more sensitive to melatonin, and the recommended range is considerably lower. The American Academy of Pediatrics advises starting at the lowest possible dose, typically 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. Experts generally advise against giving melatonin to children under 5.
Long-term safety in children is still an open question. Short-term use appears relatively safe, but less is known about how extended use might affect growth and development, particularly around puberty.
Doses for Older Adults
Natural melatonin production declines with age, which is one reason older adults often consider supplements. But this doesn’t mean they need higher doses. In fact, the opposite is true. Older adults tend to be more sensitive to supplemental melatonin, and the evidence suggests lower doses (0.5 to 1 mg) work just as well. Starting low also reduces the risk of next-day grogginess, a common complaint.
For older adults who may be more vulnerable to side effects from prescription sleep medications, melatonin at a low dose can be a reasonable alternative. But the same ceiling applies: going above 6 mg is unlikely to help and may make sleep worse through receptor desensitization.
What Happens If You Take Too Much
Researchers have not identified a lethal dose of melatonin in humans. A true overdose in the life-threatening sense hasn’t been documented. But taking too much can cause unpleasant symptoms: excessive daytime sleepiness, headaches, dizziness, nausea, and in children, bedwetting. These effects are generally short-lived given how quickly melatonin leaves the body, but they can disrupt the next day.
The more insidious risk isn’t a single large dose but a pattern of taking too much over time. Chronically high doses can desensitize your melatonin receptors, disrupting the natural sleep-wake cycle you’re trying to fix. You may find yourself needing more to get the same effect, which only deepens the problem.
What’s Actually in the Bottle
One complication with melatonin dosing is that the label may not reflect what’s inside. A study published in JAMA analyzed 25 melatonin gummy products and found that 22 of them (88%) were inaccurately labeled. The actual melatonin content ranged from 74% to 347% of what was listed on the package. Only 3 products fell within 10% of their declared dose.
This means a pill labeled “5 mg” could contain anywhere from about 3.7 mg to over 17 mg. Some products were also found to contain undisclosed ingredients like serotonin or CBD. If you’re trying to take a careful, low dose, this variability makes it harder to control what you’re actually getting. Choosing products that carry a third-party testing seal (such as USP or NSF) can help, since these verify that the contents match the label.
Finding the Right Dose
The pattern across all the evidence points in the same direction: start low. A dose of 0.5 to 1 mg is enough for many people and mirrors the range that clinical studies have validated. If that doesn’t help after a week or two, moving up to 3 to 5 mg is reasonable. Going above 5 mg rarely adds benefit, and exceeding 10 mg is where most experts draw a hard line.
Timing matters as much as dose. Taking melatonin 30 to 90 minutes before your intended bedtime gives it enough time to reach effective levels. Taking it too early or too late can shift your sleep window in ways you didn’t intend, especially with the standard (non-slow-release) form, which hits peak concentration relatively quickly and clears fast.