Can You Overdose On Melatonin? A Look At The Side Effects And Dosage

image of different bottles of melatonin pillsDo you take melatonin pills to help you deal with frustrating periods of bad sleep? Have you taken more than the recommended amount and are worried about what might happen to you?

In this article you’ll find out about the known side effects that can arise from taking melatonin.

I’ll also explain why there’s still some debate about what the recommended dose should be, and what would be considered an overdose.

Did you know?

Melatonin works differently from most sleeping pills, and isn’t always effective for insomnia. If you’re not sure if it’s right for you or your family, you might like to read these articles:

Is melatonin safe?

Many people view melatonin as a safe sleep aid, and in fact a safe way to tackle a surprisingly wide range of health conditions.

This is mainly because melatonin is a hormone produced naturally by the body, and also because it isn’t as powerful as many prescription sleep aids.

Even though synthetic melatonin is similar to that produced in your body, it doesn’t come without risks though. And like many medications, you still need to be careful even if it’s available over the counter in your country.

The bottom line is that taking more than the recommended amount isn’t known to cause death. However, it can cause health problems in some cases, so it’s worth being aware of what to look out for.

How much is an overdose?

a bottle of melatonin pillsIf we define ‘overdose’ as an amount which is too much and usually dangerous, it’s not an easy question to answer.

There are reports of people taking just a few milligrams and feeling unwell; others have taken hundreds of milligrams and been absolutely fine.

Melatonin seems to affect people differently, with no standard dosage level which causes most people problems. A second issue is that melatonin doesn’t have an official recommended dosage in most countries.

That said, most doctors and researchers say you should take no more than 5 mg a day in most cases. And preferably much less if it’s taken for sleep problems. This was also a common maximum dosage level I found in my review of over the counter sleep aids.

Despite often seeing doses between 3 mg and 5 mg on labels, doctors often suggest that you take the lowest dosage at first, as this may well give the effect you need.

And in fact, it’s thought that even 3 mg is considerably more than necessary in most cases.

Why isn’t there a standard recommended dosage?

Melatonin is marketed and sold as a dietary supplement or natural remedy. So it hasn’t undergone the rigorous testing of organizations such as the Food and Drugs Administration in the United States.

Therefore, there’s no central body to say exactly how many milligrams you should take. So you’re left to trust the advice of anyone else who speaks up on the matter.

What do doctors recommend?

Some good advice from the University of Maryland Medical Center recommends taking a dose as close as possible to that which the body produces. And the body usually produces less than 0.3 mg per day.

They also suggest that a dose of 1 to 3 mg an hour before bed works fine for most adults. But even as little as 0.1 to 0.3 mg might work. If that dosage doesn’t work after a few days, you can increase it to 5 or 6 mg.

Even though melatonin is available over the counter in many countries, you should discuss it with your doctor first. They can tell you if it will be safe for you, and recommend the right dosage based on your medical history.

Is melatonin safe at these low doses?

Research in 2005 concluded that taking melatonin at low doses is safe for periods of 3 months or less.

More recently, the Mayoclinic also stated that it’s safe at doses between 1 and 20mg for up to 3 months. They also suggest that it’s safe for children to take long-term in recommended doses.

Even at these low doses, however, you may still experience side effects. Safe doesn’t necessarily mean no side effects – it just means that it probably won’t cause most people any serious problems.

What might happen if you take a melatonin overdose?

seek help if you take a melatonin overdoseSo what happens if you have a bottle of 3mg melatonin pills with instructions to take one before bed, but you take two or three times that amount, or even more?

According to most research, you shouldn’t be in any great danger if you take a small melatonin overdose.

And in fact, it’s common for people to take a pill too soon before bed, decide it isn’t working fast enough and take another one. Then in the night to wake up and take yet another.

Whilst this may not cause you too much trouble, it’s not the right way or safest way to use melatonin.

The more you take, the more likely it is that you’ll experience unpleasant side effects. And importantly, if 1 milligram didn’t help you sleep, 1 more milligram an hour later is unlikely to make a difference.

There’s no medical advice or research stating what would happen if you took a very high dose of melatonin. However, it’s not advisable to experiment with higher doses to try and achieve a stronger effect.

Whatever dose you take, if you experience side effects, you should seek medical attention. And if you do take a large melatonin overdose, intentionally or by accident, it’s advisable to seek emergency medical attention immediately.

Possible melatonin side effects

So what are the side effects of melatonin that you might experience at any dosage level? Let’s take a closer look.

1. Daytime drowsiness

It might sound obvious, but one side effect is of course drowsiness. The point is though, if you take melatonin at the wrong time you can end up being drowsy during the day. This could increase the risk of accidents if driving or operating heavy machinery.

2. Hormonal changes

Again this sounds obvious – you’re taking a hormone after all, right? But the effects can be serious in some cases. For example, pregnant women are advised not to take melatonin as it can have negative effects on fetus growth.

It can also reduce the libido of both men and women, as well as interfere with women’s ovulation and men’s sperm count. So if you’re trying to get pregnant, melatonin is probably something to avoid.

3. Mood changes

This is especially likely if you take too much melatonin. You may experience a range of mood changes such as sadness, worsening depression or even feeling over-excitable. If you suffer from any kind of depressive illness, you should avoid melatonin unless your doctor recommends it.

4. Hallucinations, paranoia and disorientation

If you take a large overdose you may experience hallucinations, delusions, disorientation, confusion or paranoia.

5. Increase in vivid dreams and unusual sleep behavior

People often report that they have very vivid dreams when taking larger amounts of melatonin. It can also increase the frequency of sleep disorders such as sleep walking and nightmares.

6. Physiological effects

Melatonin has been found to have various effects on the body. This includes lowering blood pressure, or conversely raising it if you’re taking drugs to control it. It may have effects on blood sugar levels and cholesterol.

It can also bring about further problems for type 1 diabetics. This is due to a reduction in tolerance to insulin as well as increasing blood sugar levels.

7. Risk of seizures

This is a particular risk if you overdose on melatonin or have any existing kind of seizure disorder. Again this can be potentially serious and another good reason to be careful with how much you take.

8. Nausea and other stomach problems

This is one of the more common side effects of melatonin, even at low doses. You may experience nausea, vomiting, stomach pains or diarrhea.

9. Risks to infants through breast feeding

Melatonin is possibly not safe for infants, even though some sources argue that it’s safe for children. Breast feeding mothers should avoid melatonin as not enough is known about its safety at this time.

10. Allergic reaction

In some rare cases you may experience a severe allergic reaction. This could result in a rash, swelling of any parts of the face, tongue or throat, itching, dizziness and trouble breathing. You should seek immediate emergency medical help if these symptoms occur.

11. Increased risk of contracting immune system disorders

Melatonin may increase the risk of contracting autoimmune disorders such as Hepatitis or Crohn’s disease. For this reason, people who already have an autoimmune disorder should consult a doctor before taking melatonin.

12. Risk of liver damage

There’s thought to be an increased risk of liver damage. This is another reason people who have problems with alcohol misuse need to consult a doctor before taking it.

Interactions with other drugs

Melatonin can interact with other drugs, so you should consult a doctor if you’re taking, or planning on taking any of the following:

  • Blood thinners, such as Warfarin or Heparin.
  • Blood pressure medicine, such as Nifedipine.
  • Drugs to prevent seizures.
  • Drugs which affect your immune system.
  • Psychiatric medications, especially anti-psychotics or anti-anxiety drugs such as Benzodiazepines.
  • Anything containing caffeine or alcohol. Caffeine reduces the quantity of melatonin so makes it less effective. And therefore more likely you’ll decide to take more and risk having an overdose.
  • Anything which can make you drowsy, such as sedatives, some cough medicines and anti-histamines, muscle relaxants, other sleeping pills and some pain killers – especially narcotics.
  • Medication for diabetes.
  • Fluvoxamine (Luvox), which can decrease the amount of melatonin your body can absorb and increase the risk of side effects.
  • Medication that slows blood clotting (anti-coagulants).

For an extensive list of medications which can interact with melatonin, have a look at the article.


So can you overdose on Melatonin? It would appear that the answer is yes, if by overdose you mean feel unwell. But what might happen, if anything at all, is impossible to predict.

As with most substances, the symptoms may vary greatly from one person to the next. Melatonin isn’t known to cause death, but can make some people feel sick.

You can see that there’s a long list of potentially harmful effects of taking melatonin. But there are also additional risks for certain groups of people. So I recommend you stick to the recommended doses that major organizations such as the Mayoclinic offer.

If you’re thinking of trying it, for any medical condition, it’s a good idea to talk it over with your doctor first.

Even though it’s available over the counter in some countries, it’s a good idea to get the approval of a medical professional who knows your medical history. They can also advise you on the best dosage to take in  your case.

And once again, if you do take a melatonin overdose, please seek emergency medical help straight away.

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407 CommentsLeave a comment

  • I take 15 mg of melatonin…have for years. I am a “true” insomniac and it helps my mind slow down. I have never seen anyone who had a bad reaction to it although it certainly is possible. Even with it there are many nights I am awake all night. Too bad there is nothing safe on the market that actually works. We all need good quality sleep.

    • Hi Avi
      I would say probably not! If 5mg doesn’t work for you, an increase probably won’t either. But if you’re not sure, ask your doctor for their opinion.

  • I recently switched to Melatonin, as I have been taking Benadryl to sleep for 4 years and heard it can cause infertility. I thought Melatonin might be a safer option, so I got the 10mg dissolvable wafers. The first night I took one and things were fine; I fell right to sleep and woke up the next day with no problems. The second night it seemed 1 didn’t work, so I took two which did the trick. However, the next day I felt groggy and began to feel severely depressed throughout the day, which is extremely unusual for me. I couldn’t figure out what was wrong with me until I realized that the Melatonin was the only thing out of the ordinary in my routine that could cause such a change. I was so depressed I could hardly even stand to go grocery shopping, and actually sat in my car in the parking lot and cried for no apparent reason. Then in the evening I started getting severe stomach pains and had to lay down, I couldn’t even put my groceries away. I very rarely if ever experience side effects to medications and have been on various sleep aids since 2005, so in my opinion Melatonin is actually dangerous to well-being and I will not take it again! Some might say I just need to lower the dosage back to 1 tablet and that 20mg was too much, but I’m too scared to take it again! It’s nearly 24 hours later now after day 2 of taking it and I’m still feeling the effects. I’m not sure what to take now though! :/ just wanted to share my experience for anyone considering taking it; I’m 33 and otherwise have no physical or mental issues so I have no idea why it affected me this way.

    • Hi Jan
      Thanks for your comment. By the time you read this, hopefully things will be back to normal. Some people do just find that melatonin isn’t for them, though it does seem you had a particularly strong reaction.

    • Hi Christina
      I don’t know of any serious interactions, but since they can both cause symptoms such as drowsiness, it’s probably a good idea to ask your prescribing doctor before taking them together.

  • I recently started taking 15 mg. I’ve been taking it for a while now and I feel as if my body adapts to the dosage and then won’t work!! I go off and on for long periods of time. But I recently started taking 15mg ( I was taking 10) and I feel fine. I feel like if I don’t get 8-10 hours of sleep I will be very tired and end up crashing out around 1-2pm. I try not to keep taking it because I don’t want to depend on it.

    • Hi Sue
      Hopefully she will be, yes. But I would still contact emergency services and ask their advice if it happens again or she is feeling unwell since then. I know you wrote this comment 2 days ago, and I’m sorry I couldn’t reply sooner. I hope she was fine!

  • I take 30 MG. My sister takes 60mg. I like it. I fall asleep and have no memory of dreams. I wake up rested and feel like a million dollars!!! I have sleep apenea , some nights are rough . Last night I slept only 4 hours, but usually 8-9 hours is good for me. I know many people that use this medication to sleep and I have never heard of anything negative!!

  • For me, I have found that 100mg is my max dose. I can take any dose between 1mg to 100mg with no problem. I started taking melatonin when I was maybe 11 years old. I periodically need something to help me sleep. I do not believe that taking melatonin is harmful in any way when you take it within YOUR maximum dose. There are times I will take 100mg every night for months, then take no melatonin every night for months with no problems at all. Sometimes I only need melatonin for 1 night. My body is perfectly healthy. I recently donated my kidney and get regular tests run on my body. My liver, kidney, heart, etc. are and have been perfectly fine. My blood pressure is great. My hormones and mood is normal. If a study is ever done on the effects of long term, high melatonin doses on the human body, I would definitely participate to show that there are no harmful effects to large doses used for long periods of time. And to show that everybody has a different max dose. If 10mg doesn’t help you sleep, try 20mg. When I go past my max dose, my face gets flushed (red, warm cheeks), that’s all. I’m sure everyone will react differently when they reach their max dose. Pay close attention to your body as you take any dose. Hope this helps bring comfort to those trying to find a non-addictive sleep aid.

    P.S. For those wondering why I am not just taking a prescription sleeping pill, I have tried. Prescription sleeping pills do not make me tired. Every body is made uniquely different and reacts different to EVERYTHING!!! Best thing anyone can ever do is pay attention to YOUR BODY!!

    • Hi Jenae
      Thanks for your comment. It’s always interesting to hear from someone who has experience of a higher dose. However, I don’t support the idea of experimenting to find your maximum dose by looking out for side effects. Firstly, that could be dangerous for some people. And secondly, there’s really no need to do that when it’s thought that very small doses can be just as effective as higher, if not more so.

  • I know this may sound weird but whenever I take more than 10 mg of melatonin I sometimes wake up being attacked by dark shaped figures in my room. Does anyone else experience this?

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