In large amounts, melatonin supplements can disrupt your circadian rhythms, which includes your sleep patterns. They may also react with body chemicals to cause other symptoms. However, there is no standard dose as people react differently. This makes it hard to define an overdose.

While melatonin is a hormone naturally produced in the body, taking too much supplementary melatonin can disrupt your circadian rhythm (also called your sleep-wake cycle). It may also cause other unwanted side effects.

So, yes, you can technically overdose on melatonin.

However, a melatonin overdose can be hard to define since there isn’t an official standard safe dosage for everyone.

Some people are more sensitive than others to the effects of melatonin. A dose that might trigger side effects in one person may have little effect on someone else.

Healthy children under three should avoid melatonin unless otherwise directed by a doctor. Possible melatonin side effects in children include headaches, drowsiness, dizziness, agitation, and bedwetting.

In adults, the standard dose used in studies ranges between 1 and 10 mg, although there isn’t currently a definitive “best” dosage. It’s believed doses in the range of 30 mg may be harmful.

In general, starting low and moving up slowly and carefully is better if you see encouraging results. Speak with a doctor if your sleep problems persist.

A safe dose of melatonin is the lowest dose that’s effective in helping you fall asleep without causing side effects. Generally, a dose between 0.2 and 5 mg is considered a safe starting dose.

A safe dose will depend on your body weight, age, and sensitivity to the supplement.

Too much melatonin can have the opposite effect of its intended purpose. It can make it harder to sleep because your circadian rhythms will be disrupted.

An overdose can also leave you groggy and sleepy during the day and give you nightmares or vivid dreams at night. You can also experience:

For some people, too much melatonin can affect their blood pressure. Medications that lower blood pressure, such as calcium channel blockers and beta-blockers, may reduce your body’s natural production of melatonin.

However, taking a supplement to make up for lower melatonin levels may not always be advisable. Be sure to talk with your doctor about melatonin and other supplements you take if you’ve been prescribed medications to help control your blood pressure.

Because melatonin can affect your sleep-wake cycle, avoid taking it with alcohol or caffeine. These can interfere with your circadian rhythm and your natural melatonin production.

Before starting melatonin or any over-the-counter medication or supplement, talk with your doctor. This is especially true if you take other medications.

For example, birth control pills may cause your body to produce more melatonin, so taking a supplement could push your levels into an unhealthy range.

Taking melatonin with anticoagulant drugs, such as warfarin (Coumadin), could increase your risk of bleeding.

You should also avoid taking melatonin if you take corticosteroids to suppress your immune response in conditions such as rheumatoid arthritis or lupus.

If you think you may have overdosed on melatonin, call Poison Control at 800-222-1222.

You should call 911 and seek emergency help if you have symptoms such as:

These signs may not be related to melatonin or an interaction between melatonin and other medications. However, they shouldn’t be ignored, as they can indicate a medical emergency.

Though melatonin can be very helpful for some people needing a little extra help falling and staying asleep, it’s not for everyone. You may not tolerate it well, even at low doses. You may find that it doesn’t help you sleep, regardless of the dose.

If insomnia is a problem, talk with a sleep specialist. There may be other lifestyle changes you can make that can help, such as cutting back on caffeine and alcohol or changing your bedtime routine.

You’re not likely to have any serious medical problems due to taking melatonin but you should treat it carefully.

The Food and Drug Administration doesn’t regulate this supplement, so there are no official dosing guidelines to follow. For further questions, talk with a doctor, a healthcare professional specializing in sleep health, or a pharmacist.

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