Can You Take Too Much Melatonin? How Much Can Kill You?

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It is possible to overdose on melatonin? Can taking too much do harm?

Chances are if you’re asking this question — you’ve probably been experimenting with supplements to help you sleep.

Lots of people take melatonin to try and help them fall asleep faster or overcome the symptoms of jet lag. If you’ve been counting sheep for hours, it may be tempting to pop a few pills to catch some zzz’s. If it still doesn’t work, you may start getting desperate and decide to take a couple more pills to knock yourself out.

Sound familiar? You may be wondering if this could lead to any potentially dangerous consequences. Keep reading to get the essential info on melatonin safety, side effects, and dosage.

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Melatonin Safety

Most people feel perfectly safe taking an over-the-counter supplement like this one for sleep. In fact, melatonin is one of the most popular sleep aids and is projected to generate 1.5 billion in revenue worldwide by 2021. Aside from insomnia and jet lag, other uses include headaches, cancer, tinnitus, Alzheimer’s, and protection from radiation.

Unlike most over-the-counter (OTC) products that come from plants, vitamins, and minerals, this one is a hormone that is produced naturally by the body and is linked to the circadian rhythm. Despite being considered a relatively safe supplement, OTC use has been banned for years in Japan, Australia, the UK, parts of the European Union, and most recently Canada. In these countries, the only way to take this hormone is as a prescription — but, why?

Investigations into OTC products have discovered that melatonin supplements may contain doses that vary anywhere from -83% up to +478% of what is labeled on the bottle. Even more alarming, some products also tested positive for serotonin, a neurotransmitter and controlled substance used to treat many neurological disorders.

A Woman who is Awake in Bed Thinks of Pill Bottle Illustration

Even though the synthetic alternative is somewhat similar to the one produced in the body, it doesn’t come without its risks. Higher doses could lead to unwanted side effects, especially for those with allergies/sensitivities, people taking medications that have known drug interactions with this hormone, pregnant women, and those with prediabetes/diabetes.

And finally, to answer the burning question, can you OD on melatonin, the answer appears to be no.

The LD50 (lethal dose for 50% of subjects) couldn’t be established in animals and a dose of up to 800mg/kg wasn’t found to be lethal in humans.

To sum it up — melatonin is not known to be a potential cause of death, but you do need to be aware of possible complications if you overdose.

Melatonin Pill Side Effects

Daytime Sleepiness

Drowsiness is undoubtedly amongst the most visible and common side effects when it comes to overdoing it with your supplementation. The idea is that if you take this supplement at the wrong time of the day, you are likely to start feeling drowsy. This could also lead to increased risks when you are operating certain heavy machinery or when you are driving, for example.

Illustration of Tired Zombie in the Market

Hormonal Changes

When you’re taking a hormone – hormonal changes are bound to happen. However, this could be far more serious than you think. For instance, pregnant women are not advised to take melatonin as not enough research has been done to know if it is safe during pregnancy.

It is also something that could potentially reduce libido in both sexes. It is capable of interfering with the sperm count of men and the ovulation cycles of women. With this said, if you are trying to have a baby, you should probably talk to your doctor before taking this supplement.

Some research suggests that it could delay puberty and cause other changes in children, so talk to your child’s pediatrician if you have concerns about their sleep.


Another widespread consequence of taking a little bit too much of this supplement is a severe headache in the morning. One the one hand, some research has found that melatonin supplements may help to prevent headaches and migraines. 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 could be another unpleasant side effect from taking too much melatonin. It could also be triggered by an allergic reaction to the supplement. Either way, dizziness is something quite unpleasant and is capable of severely disrupting your functioning.

A woman leaning on a chair showing fatigue


If you take a higher dose than what’s necessary, you could experience delusions, paranoia, confusion, or hallucinations. Because this hormone is closely tied to other neurotransmitters that regulate mood and behavior, higher doses could lead to chemical imbalances and these unpleasant symptoms.

Stomach Issues

This is undoubtedly one of the most common side effects of melatonin, regardless of whether you take it in a regular amount or you overdose it. You may easily experience stomach issues such as diarrhea, vomiting, and nausea. These are quite unpleasant, and this is something that you don’t want to deal with.

Anxiety & Depression

Sad Woman Laying in Bed Illustration

Anxiety and depression are commonly associated with hormonal imbalances and could be induced by taking higher doses of this supplement. If you start experiencing any mental health changes after taking melatonin, speak to your doctor immediately.

How Much Melatonin is Too Much?

How Much Should You Take?

The majority of studies have researched doses ranging from 0.3 mg to 10 mg as the safest and most effective dose. However, the ideal dose depends on age, weight, the problem you’re trying to address, and any current medications that you’re taking. Most experts recommended starting at the lowest dose and slowly increasing until you get the desired effect.

If you’re unsure which dose to start with, it’s best to talk to your doctor.

Different Bottles of Melatonin on the Shelf

10mg Dosage

This is the highest dose that is typically used for treating sleep-related conditions and hasn’t been associated with toxicity. 10mg was the dose used in one study to handle circadian rhythm disorders in people who are blind. The authors of the study concluded that this high dose should always be supervised by a physician.

20mg Dosage

This is a higher amount of the hormone and should only be used for specific purposes under the supervision of a doctor. For example, some research has looked at the use of 20mg of melatonin combined with cancer treatments like radiation and chemotherapy. This dose should only be prescribed by and taken under the supervision of a doctor.

30mg Dosage

The 30 mg melatonin dosage is substantial. Some studies have used doses of 20-40 mg to prevent and treat clot-forming cells (thrombocytopenia) associated with cancer chemotherapy.

100mg Dosage

This is a serious dosage, and it shouldn’t be used at all. With this in mind, it’s important to note that this would result in a lot of unwanted effects which could be potentially very harmful. Keep this in consideration.

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Frequently Asked Questions

What is a Lethal Dose of Melatonin?

Every single medicine has its own LD 50. This is the lethal dose when 50% of the experimental subjects would die of exposure. Melatonin is known to be relatively safe and an LD50 couldn’t be established. Even extremely high doses weren’t lethal in animals.

How Long Does it Last?

The plasma half-life is quite short and ranges between 20 and 50 minutes. This means that approximately only half of the dose remains in your system after this amount of time. This means that while it may help you fall asleep faster, it likely won’t help you to stay asleep or increase the quality of your sleep.

Why Do People Take Melatonin?

Melatonin is the hormone released by our brains once we fall asleep and it is actively used to handle a range of different conditions. Apart from the regular sleep-related ones, melatonin is also known for being particularly useful in various cancer treatments as an additional ingredient to use through chemotherapy, for instance.

Is Melatonin Habit Forming?

Melatonin is not considered to be habit-forming or cause dependencies. It is generally safe for short-term use. If you find yourself using it every day for longer than 2 weeks, it’s important to talk to your doctor about your symptoms to rule out underlying conditions causing problems with your sleep.

Should Children Take It?

Melatonin has been studied for children with certain conditions, such as autism. There are limited studies about its effectiveness and safety in other children. If you’re considering using melatonin with your child, talk to their pediatrician first.

Pediatrician Checking Baby in Mother's Lap

What Should You Do if Consume Too Much?

If you’re worried that you’ve taken too much, call your doctor or a poison control center. While melatonin is considered to be very safe and has a low toxicity profile, it could cause unpleasant side effects and be dangerous for people with certain conditions or taking certain medications.

What Happens If I Take Melatonin With Another Medication?

According to the Mayo Clinic, taking melatonin should be safe for most people, though in some circumstances it can interact with other medications such as blood thinners, blood pressure medications, anticonvulsants, oral contraceptives and others. However, this doesn’t mean the interaction will be dangerous, in some cases it may just inhibit melatonin’s ability to simulate drowsiness.

Before taking melatonin, be sure to discuss your current medications with your doctor to be sure it’s the right choice for you.

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Our Final Thoughts

Melatonin is a natural hormone that is made in the body. It’s important for regulating many activities, including sleep. It has many benefits and a high safety profile with few side effects.

That being said, it is possible to take too much melatonin and experience unpleasant symptoms like headaches, drowsiness, an upset stomach, and others. The best way to avoid these is to start with the lowest possible dose and slowly increase until you see the desired effect. As always, before taking any supplement, speak with your doctor.

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