Melatonin is not deadly at any dose that has been reliably documented in humans. No study in humans or animals has produced a death from melatonin alone, even at doses far beyond what the body naturally produces. That said, the supplement is not entirely without risk, especially for children, people on certain medications, or anyone taking wildly inaccurate doses from mislabeled products.
No Established Lethal Dose Exists
Toxicology research on melatonin has found no lethal dose in humans or animals, even at what researchers call “supraphysiological doses,” meaning amounts many times higher than what your body makes on its own. Your body naturally produces a small amount of melatonin each evening to signal that it’s time to sleep, and that production declines with age. Most over-the-counter supplements contain 1 to 10 milligrams per dose, while research from MIT found that doses as low as 0.3 milligrams are enough to improve sleep in older adults.
There is one published forensic case where melatonin was listed as a contributing factor in a death, but it involved a combination of melatonin and diphenhydramine (the active ingredient in Benadryl). The authors noted it was the first such case in medical literature, and the death was attributed to the combined toxicity of both substances, not melatonin alone. Outside of that single case, the medical literature contains no reports of lethal melatonin concentrations in adults.
What Happens if You Take Too Much
Taking a large amount of melatonin won’t kill you, but it can make you feel terrible. The most commonly reported symptoms of excessive intake include drowsiness, dizziness, fatigue, headache, and confusion. In more significant overdoses, people have experienced low blood pressure, rapid heart rate, a drop in body temperature, and vivid nightmares. One case report described lethargy and disorientation after a 24-milligram dose, while another documented lethargy and severe delayed low blood pressure after 180 milligrams.
These effects are unpleasant but temporary. Hospital treatment for melatonin overdose is supportive, meaning doctors monitor your vital signs and wait for the substance to clear your system. There is no specific antidote because one has never been needed.
The Real Risks: Interactions and Mislabeling
Where melatonin can become genuinely dangerous is in combination with other substances. According to the Mayo Clinic, melatonin interacts with several categories of medication: blood thinners, seizure medications, birth control, blood pressure drugs, diabetes medications, immunosuppressants, and drugs processed by the liver. If you’re taking any of these, adding melatonin could amplify or reduce the effect of your prescription in ways that matter.
There’s also a labeling problem. A study published in JAMA found that 88% of melatonin gummies tested contained amounts that didn’t match their labels. The actual melatonin content ranged from 74% to 347% of what was declared on the package. That means a gummy labeled as 5 milligrams could contain anywhere from roughly 3.7 to over 17 milligrams. Since melatonin is sold as a dietary supplement rather than a pharmaceutical, it doesn’t go through the same quality controls as prescription drugs. You may be taking far more (or less) than you think.
Children Face Higher Risk of Accidental Ingestion
The biggest safety concern with melatonin right now involves young children getting into bottles unsupervised. Between 2019 and 2022, melatonin was responsible for roughly 11,000 emergency department visits among infants and children aged five and under in the United States, making up about 7% of all ER visits for unsupervised medication exposure in that age group. Poison control calls for pediatric melatonin exposures surged 530% between 2012 and 2021.
The good news is that even in these cases, the outcomes are overwhelmingly mild. A study of poison center data found that 98% of pediatric melatonin exposures resulted in minimal or no effects. Still, the sheer number of incidents reflects how casually melatonin is stored in many households, often in the form of flavored gummies that look and taste like candy to a toddler. Keeping supplements out of reach matters just as much for melatonin as it does for any other medication.
How Much You Actually Need
Most people take far more melatonin than necessary. Research from MIT found that a 0.3-milligram dose, which closely mimics the amount your body produces naturally, was effective at improving sleep quality in people over 50. The 3-milligram dose commonly sold in stores is ten times that amount, and many products go up to 10 or even 20 milligrams. Higher doses don’t necessarily produce better sleep and can cause next-day grogginess.
If you want to try melatonin, starting with the smallest available dose and increasing gradually gives you better odds of finding an amount that helps without side effects. Taking it about 30 minutes before your intended bedtime aligns with how your body’s own melatonin release works.