Melatonin is a naturally occurring hormone that helps regulate the body’s sleep-wake cycle and is widely sold as an over-the-counter dietary supplement in the United States. Although often used to promote sleep in both children and adults, melatonin is regulated differently than prescription medicines, which raises concerns about product quality, dosing accuracy, and long-term safety. This article explains what melatonin is, why it is legally available without a prescription, and important considerations for using it safely.
What Is Melatonin?
How does your body know when it’s time to sleep? Your brain makes its own sleep hormone when darkness falls and stops making it in the morning when the light returns.
This hormone is called melatonin and has been sold as a dietary supplement to promote natural sleep cycles for decades. Many healthcare providers recommend it for all age groups to counteract the effects of medicines, jet lag, or for trouble sleeping.
Why Is Melatonin Legal in the United States?
In most countries outside the United States, melatonin is available by prescription only, the same as other human hormones. Why do we allow it over the counter in the United States? What does this mean for people who want to use melatonin safely?
The Food and Drug Administration (FDA) has different regulations from Congress for dietary supplements compared to other medicines. Melatonin is found in some foods, which means it is eligible to be sold as a dietary supplement. If the product keeps its claims somewhat vague, like “supporting healthy sleep,” and does not claim to diagnose, treat, cure, or prevent disease, the manufacturer has free marketing. The FDA can step in only if the product is shown to have a problem.
Is Taking Melatonin Safe?
It may come as a surprise that, unlike medicines, dietary supplements do not have to be proven safe and effective before they are sold, and they do not have to closely control the ingredients in the bottle. We go more in-depth on whether melatonin is poisonous in our article “Is Melatonin Poisonous?”.
Melatonin supplements may be of poor quality and may not contain the amount of the active ingredient that is stated on the label. More importantly, it could contain an “undeclared ingredient” that is not listed on the label but was added to the product, which may have important consequences for health.
Countries where melatonin is only available by prescription do not have these worries. However, no one inside or outside the US knows whether long-term supplements of this natural hormone are safe if used year after year.
Luckily, serious adverse effects are uncommon. There may be a “hangover-like” effect the morning after taking a nighttime dose. Some experience disorientation, confusion, excessive drowsiness, and dizziness.
Real-Life Calls to the Missouri Poison Center
You can purchase melatonin as tablets, chewable tablets, gummies, liquids, skin patches, and sometimes food and drinks. Children are naturally attracted to products that appear to be candy and food, and sometimes teens and young adults take excessive melatonin doses for their own purposes. In 2025, the Missouri Poison Center received nearly 1,300 cases about melatonin in children and young adults and 100 cases in adults.
- A 3-year-old ate 15 gummy melatonin supplements from a bottle that did not have a child-resistant lid. The child became drowsy but was able to stay at home with close observation and follow-up from the Missouri Poison Center.
- A 13-year-old intentionally ate more than 40 tablets of melatonin. A healthcare facility monitored her for adverse effects and then offered mental health support.
- 5 children under 6 years-old got into a bottle of melatonin at the babysitter’s house and ate an unknown amount. The children had some minor drowsiness, but all were able to remain at home with follow-up from the Missouri Poison Center.
Can You Overdose on Melatonin?
Yes, it is possible to take too much melatonin, but life-threatening overdoses are rare. Unlike many prescription sleep medicines, melatonin does not typically cause severe breathing problems or organ damage when taken alone. However, large amounts can overwhelm the body’s normal sleep–wake signaling. This may lead to uncomfortable and sometimes unexpected symptoms, especially in children.
Symptoms of excessive melatonin intake may include extreme drowsiness, confusion, headache, nausea, vomiting, dizziness. In children and teens, high doses can also cause agitation or disorientation rather than sleepiness. While most cases can be managed with observation and guidance from a poison center, any intentional overdose, severe symptoms, or ingestion by a young child should be taken seriously and discussed with your poison center.
Final Thoughts
If your healthcare provider recommends melatonin for someone in your family, find a product from a reputable manufacturer. Do not brand-hop without a good reason. Treat melatonin like a prescription medicine and keep it locked up and away from curious children. Don’t leave it around to act as a temptation to your teens to experiment.
Frequently Asked Questions
Short-term use of melatonin may be appropriate for some children when recommended by a healthcare provider, particularly for sleep difficulties related to neurodevelopmental conditions or temporary schedule disruptions. However, children’s brains are still developing, and melatonin may affect hormones involved in growth and puberty. Try behavioral sleep strategies first. Don’t use melatonin as a nightly, long-term solution without medical guidance.
There is not enough high-quality research to confirm that melatonin supplements are safe during pregnancy. Although the body naturally produces melatonin, and it plays a role in fetal development, supplement doses are often much higher than natural levels. Because supplements do not have strict regulations, pregnant individuals should avoid melatonin unless a healthcare provider specifically recommends it.
Melatonin is absorbed quickly and typically reaches peak levels within about an hour of ingestion. It is eliminated from the body within several hours. Extended-release formulations, higher doses, older age, and certain medications can cause melatonin to remain in your system longer and increase next-day drowsiness.
Yes, melatonin may increase vivid dreams or nightmares in some people. It can intensify REM sleep, the stage of sleep most associated with dreaming. This may make dreams feel more realistic or emotionally charged. Lowering the dose or taking melatonin earlier in the evening may reduce this effect. Discuss persistent, disturbing dreams with a healthcare professional.
When used as directed, melatonin is not considered poisonous. However, excessive doses, accidental ingestions, or use in young children can cause symptoms. Read our more in-depth article on melatonin toxicity here.
Referencing content from this page? Please attribute the Missouri Poison Center with either of these links:
https://missouripoisoncenter.org/ or https://missouripoisoncenter.org/melatonin-mother-natures-sleep-aid/
Suggested APA citation:
Missouri Poison Center Trending Topics Blog. (2016, December 21). Melatonin: Mother Nature’s Sleep Aid?. https://missouripoisoncenter.org/melatonin-mother-natures-sleep-aid/