A melatonin overdose is unlikely. However, some people have experienced lethargy, low blood pressure, and disorientation after taking high doses. Side effects and interactions with other drugs can also occur.

Melatonin is a naturally occurring hormone in the body, though people may take it as a supplement.

There have only been two recorded cases of melatonin overdose since 1997. Excessive consumption can cause lethargy, disorientation, and low blood pressure.

It is important for people using melatonin to be mindful of side effects and always begin with the lowest dose possible.

This article covers what melatonin is, its uses, and possible side effects.

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Melatonin is a naturally occurring hormone in the body that helps regulate the sleep cycle. The pineal gland in the brain produces melatonin.

Melatonin levels increase and decrease throughout the day. Typically, melatonin levels rise through the evening and remain high overnight, allowing a person to sleep.

In the morning, due to sunlight hitting the eye, the levels drop again, allowing a person to wake up.

Some vegetables and fruit contain small amounts of melatonin, and it is also available as an over-the-counter supplement.

In the short term, taking supplemental melatonin will increase melatonin, signaling the body to fall asleep. It works best for jet lag, though it may also help in insomnia or other sleep-related problems.

Learn more about melatonin here.

The symptoms of melatonin consumption will vary from person to person. Some may find that taking too much melatonin causes them to feel extremely sleepy during unintended times or cause intense dreams or nightmares.

Other symptoms of a melatonin consumption may include:

Melatonin overdose symptoms

Melatonin overdose is rare. In the limited cases of melatonin overdose, people experienced the following symptoms:

  • lethargy
  • low blood pressure
  • disorientation

A typical dose of melatonin is between 1 mg and 5 mg. Doctors may advise that people only take melatonin two-three times a week rather than every night.

Doctors typically prescribe a lower dose at first. If it is well-tolerated though not effective, they may slowly increase the dose.

Age, weight, and overall sensitivity to the supplement affect how much melatonin a person should take.

Melatonin in adults and children

Doctors may recommend melatonin for children with neurodevelopmental disorders that make it difficult for them to sleep.

Conditions that may impact a child’s sleep include:

If a doctor prescribes melatonin for a child, a parent or caregiver needs to ensure they follow the exact prescribed dosage.

A 2021 review found insufficient evidence to recommend melatonin use in children without diagnosed neurodevelopmental disorders.

Learn more about melatonin use for children here.

Melatonin can have a direct effect on a person’s sleep cycle. A person should avoid taking melatonin alongside products containing caffeine or alcohol, as both of these can affect a person’s ability to fall asleep.

Anyone who is taking other medications should discuss possible side effects with their prescribing doctor. Prescription and over-the-counter drugs can interact with melatonin supplements.

People with high blood pressure or taking medications that lower blood pressure should speak with a doctor before using melatonin.

Blood pressure medications may decrease a person’s natural production of melatonin, which may prompt them to take melatonin to help offset the imbalance. However, melatonin can cause changes in blood pressure, including unsafe and unexpected spikes.

Some medications, such as birth control, can cause the body to produce more melatonin. Taking a supplement may cause melatonin levels to increase too much, producing unwanted side effects.

Immune suppressors and some blood thinners may also react with melatonin. For example, melatonin may intensify the effects of some blood thinners, causing a risk of excessive bleeding.

A person should speak with a doctor if they are considering taking melatonin for trouble sleeping. A doctor can recommend the correct dose and tell a person whether their medication is likely to cause unsafe side effects.

People should also report any unwanted side effects from melatonin to a doctor as soon as possible.

A person using melatonin should contact their local emergency number if they experience any of the following side effects:

  • extremely high blood pressure
  • shortness of breath
  • sudden chest pain

Serious side effects resulting from a melatonin overdose are rare. Treatment for a melatonin overdose will depend on the severity of the symptoms.

In an emergency, a doctor will focus on stabilizing the person’s condition. A person experiencing chest pain or trouble breathing may require additional medical interventions.

In most cases, the best treatment is to reduce or eliminate melatonin use. If a person has to stop using melatonin because of side effects, a doctor or sleep specialist may be able to recommend other methods to help the person fall asleep.

Melatonin is a naturally-occurring hormone that is also available in supplement form. People often take melatonin supplements to help them with sleep difficulties.

All people should start with the smallest dose of melatonin possible to avoid potential overdose and consult a doctor before they begin.

For some people living with insomnia or having trouble sleeping, a sleep specialist may be able to give additional suggestions. A sleep specialist may recommend cutting out caffeine or reducing alcohol consumption.