Melatonin safety: What you need to know

Melatonin is a hormone found naturally in the body. It helps control your sleep patterns.

Light affects how much melatonin the body produces. In the evening, the body releases more melatonin to prepare you for sleep. By early morning, melatonin levels drop to prepare the body for being awake. Melatonin is found in a number of foods. A synthetic (man-made) form of melatonin is also sold as a dietary supplement to help promote restful sleep.

Melatonin supplements appear to be generally safe for most people when used occasionally and for a short time. However, less is known about the long-term safety of melatonin supplements.

Some adults who take melatonin have side effects. These may include:

• Headaches
• Daytime sleepiness
• Dizziness
• Stomach cramps
• Irritability
• Short-term feelings of depression

Because melatonin can cause drowsiness, don’t drive or use machinery within five hours of taking the supplement.

In adults, typical doses of melatonin range from 0.3 mg to 5 mg at bedtime. However, your healthcare provider may recommend different doses for you based on the reason you’re using it. If you have questions about how to take melatonin, ask your pharmacist or healthcare provider.

Be sure to follow the directions on the melatonin supplement label. This will tell you how much melatonin to take and how often to take it. Don’t take more than the recommended amount unless directed by your healthcare provider. Taking more melatonin doesn’t make it work faster or better, and it may even be harmful.

Melatonin is unlikely to be habit-forming and appears to be safe for most people when used on a short-term basis.

Not enough is known about the safety of melatonin when used during pregnancy. Until more is known, it's best not to use melatonin while pregnant or trying to become pregnant.

Melatonin supplements appear to be safe for most children for short-term use, but less is known about the long-term effects. For example, because melatonin is a hormone, there are concerns about how it might impact development or puberty.

Possible melatonin supplement side effects in children include:

• Drowsiness
• Increased bedwetting or urination in the evening
• Headaches
• Dizziness
• Agitation

Melatonin should not be a substitute for healthy sleep habits. If you're considering taking a melatonin supplement to help you sleep, check with your healthcare provider first, especially if you have a health condition or take medication. Melatonin can interact with certain drugs, including those taken for birth control, blood clotting disorders, high blood pressure and diabetes. As with other dietary supplements, melatonin isn’t approved by the Food and Drug Administration (FDA) for safety or effectiveness. Be sure to discuss the potential benefits and risks of a melatonin supplement with your provider so they can help decide if it’s right for you.

Published April 2021.