Can You Overdose on Melatonin? How to Use Melatonin Safely

5mg Dosage

For insomnia, most doctors recommend a dosage of melatonin somewhere between 0.3 and 5 milligrams. In one study⁸ comparing the effects of 1 milligram and 5 milligrams, participants who took 5 milligrams showed an overall improvement in subjective sleep quality but actually slept for less time than those who took 1 milligram. The study also showed that 5 milligrams was the most effective dosage for jet lag.

10mg Dosage

10 milligrams is the highest dose that is typically used for treating sleep-related conditions and hasn’t been associated with side effects. In one classic study⁹ from 2000, researchers used 10 milligrams of melatonin to regulate circadian rhythm disorders in people who are blind. 10 milligrams was effective in this case, but the authors of the study concluded that this dose should always be supervised by a physician.

20mg Dosage

A 20-milligram dosage of melatonin should only be used for specific purposes under the supervision of a doctor. For example, some research¹⁰ has looked at the use of 20 milligrams of melatonin combined with cancer treatments like radiation and chemotherapy. The researchers found that melatonin could help lower the toxicity of certain substances in chemotherapy.¹⁰ They also found a decrease in adverse effects resulting from this treatment.¹⁰

30mg Dosage

A 30-milligram dosage is substantial. Some studies¹¹ have used doses of 20-40 milligrams to prevent and treat clot-forming cells (thrombocytopenia) associated with cancer chemotherapy.

40mg Dosage

As mentioned above, doses in the range of 20-40 milligrams could help with clot-form cells linked to chemotherapy treatments.¹¹ That being said, this amount is far too high to take on your own, and we would advise against this. If you or someone you know is a cancer patient experiencing clotting issues, you might consider bringing this up with the doctor though.

100mg Dosage

100 milligrams of melatonin is a serious dosage, and it shouldn’t be used at all. It’s important to note that taking this much melatonin would likely result in a lot of unwanted — and potentially harmful — side effects.

Melatonin Side Effects

Daytime Sleepiness

Drowsiness¹² is one of the most visible and common side effects of taking too much melatonin, and this is particularly harmful if you take it at the wrong time of the day. For example, it could lead to increased risks when you are operating certain heavy machinery or driving, so always be sure to take melatonin about one or two hours before bedtime.

Hormonal Changes

When you’re taking a hormone supplement, hormonal changes are bound to happen. For example, some studies show that children who take melatonin during adolescence might experience delayed puberty¹³ since melatonin plays a vital role in triggering puberty.

Other studies have looked at melatonin’s positive impacts on fertility¹⁴ in people trying to get pregnant. Since we are still understanding how melatonin impacts other hormones in the body, there is some debate about taking melatonin while pregnant. Most agree it is safe, temporarily, at low doses, but always talk to your doctor first.

Headaches

Another possible consequence of taking too much melatonin is a severe headache in the morning.¹² On the one hand, some research has found that melatonin supplements may help prevent headaches and migraines¹⁵. However, keep in mind that this hormone is produced in your brain and as such, taking more than what’s needed could lead to chemical imbalances and quickly spiral into the very thing you’re looking to prevent — headaches.

Dizziness

Dizziness could be another unpleasant side effect of taking too much melatonin.¹² This symptom could also be triggered by an allergic reaction to the supplement. Either way, dizziness is unpleasant and is capable of severely disrupting your ability to function properly.

Paranoia

If you take a higher dose of melatonin than what’s necessary, you could experience delusions, paranoia, confusion, or hallucinations¹⁶, especially if you have major depression or a psychotic disorder. Melatonin is a hormone closely tied to other neurotransmitters that regulate mood and behavior, and therefore, higher doses could lead to chemical imbalances¹⁶. People with major depression or certain psychotic disorders are urged to speak to their doctor before adding in melatonin.

Stomach Issues

Stomach issues are another common side effect of melatonin, regardless of whether you take it in a regular amount or you overdose it.¹² You may experience stomach issues such as diarrhea, vomiting, and nausea. Any of these symptoms could disrupt your day and make it harder to function normally.

Vivid Dreams and Nightmares

Another side effect of taking melatonin is vivid dreams or nightmares.¹² This side effect occurs because supplementary melatonin seems to increase the amount of time we spend in REM sleep¹⁷– the stage of sleep when we dream. Spending more time in this sleep stage may give some people more vivid dreams or nightmares, however, this seems to be most true for those taking a high dose.¹⁷

Frequently Asked Questions

What is the lethal dose of melatonin?

Every single medicine has its own LD 50¹⁸, which is the lethal dose when 50 percent of the experimental subjects would die of exposure. Melatonin is known to be relatively safe, and in animal testing, an LD50 couldn’t be established.⁷

How long does melatonin last?

The plasma half-life for melatonin is short and ranges between 45 and 90 minutes¹⁹. This means that approximately only half of the dose remains in your system after this amount of time.¹⁹ While melatonin may help you fall asleep faster, it likely won’t help you to stay asleep or increase the quality of your sleep, unless you are taking an extended, or prolonged-release, melatonin supplement. Extended-release medications or supplements are designed to be released into the body over a longer period.

Why do people take melatonin?

Melatonin is the hormone released by our brains to foster sleep, and it is commonly used as an over-the-counter sleep aid to help with insomnia or jet lag.

Is taking melatonin habit-forming?

Taking melatonin is not considered to be habit-forming or to cause dependencies, and it is generally safe for short-term use. If you find yourself using it every day for longer than two weeks, it’s important to talk to your doctor about your symptoms to rule out underlying conditions causing problems with your sleep.

Is melatonin safe for kids?

Melatonin has been studied for children with certain conditions, such as ADHD and autism²⁰. These studies show a lot of promise in terms of melatonin reducing certain symptoms and behaviors.²⁰ There are limited studies about its effectiveness and safety in other children, though there is some concern about administering melatonin close to puberty as it may affect hormones¹². If you’re considering letting your child use melatonin, talk to their pediatrician first.

Can kids overdose on melatonin?

Yes, kids can overdose on melatonin²¹ just as adults can, and the signs a child has taken too much can include an upset stomach, vomiting, diarrhea, and tiredness.

A 10-year study found that from 2012-2021, the number of children ingesting melatonin increased by as much as 530 percent²². They went on to say that hospitalizations and more severe symptoms also increased during this time, though these primarily resulted from unintentional ingestions. Among those more severe cases, five children had to be on mechanical ventilation and two children under the age of two had died.²² However, it’s important to add that children under the age of three²³ are not recommended to take melatonin.