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

melatonin overdoseMany people view melatonin as a safe sleeping pill. And in fact a safe way to tackle a growing and surprisingly wide range of health conditions.

This is largely because melatonin is a hormone produced naturally by the body. And if it can be bought over the counter, it must be pretty safe, right?

But is that really the case, or can you overdose on melatonin? And what kind of side effects might you expect from a normal or high dose?

A difficult question

If 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 mg and feeling very unwell; others have taken hundreds of mg and been absolutely fine.

Melatonin seems to affect people differently, with no standard dosage level which causes most people problems. It could be argued then that anything over the recommended dosage would be an overdose. The problem this time though is that melatonin doesn’t have an official recommended dosage.

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

Doctors will also usually suggest that you take the lowest dosage at first, as this may give the effect you need. If not, you can take a little more the next day.

Surely there must be a recommended dosage?

There really isn’t a standard recommended dose of melatonin at the moment. And interestingly, most companies produce melatonin sleep aids in quantities far higher than the body actually produces.

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. And 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. 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 0.3mg per day.

They also suggest that a dose of 1 to 3mg 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 6mg.

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. And 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 though 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 medical damage.

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 1mg didn’t help you sleep, another 1mg 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. Even if it’s not thought to cause death, it’s possible you’ll experience some unpleasant side effects.

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.

Further reading

Does melatonin work if you have insomnia?

Melatonin for kids – right or wrong?

343 CommentsLeave a comment

  • Hi Ethan,

    I used to take Melatonin when I worked, because of stress and number of hours sleep I got (usually about 5-6 hours a night). It induced REM, and that 5-6 hours was like 7-8, woke up well rested and great. Mentioned it to other people. I told them I heard at the time to get a bottle of 1mg tablets and start with 1 and increase each night if it doesn’t work by 4, it probably wasn’t going to work. Got good comments from friends about it… well, mostly. Some said it didn’t work.

    Thanks for the informative read!

    • Hi Phil
      Thanks for your comment, and I’m glad you found the article informative. I’ve given similar advice many times in the comments here, as it’s definitely best to start with a low dose. If it doesn’t work at lower doses, then it’s unlikely to work at the very large doses people sometimes take in the hope it will do the trick.

  • Hi Ethan,
    I suffer from migraine and read about 3mg at night can help the frequency and /or intensity of them. Took for a couple weeks and it did help. I got nervous that maybe it’s too much so I stopped and bam migraine the next day. I started taking again but now I only take half a pill 1.5mg a night. Do you have any information on migraine and melatonin? Thank you, Rachel.

  • I told my son to take his chewie. He is 7 and usually listens well he says he took 4 or 5 idk if this is true the bottle didn’t have many in it and still has close to what I thought was in it. Idk if he took any as some nights he puts his chewie somewhere and doesn’t take. I hate to rush to ER if he never took them idk what to do.

    • Hi L
      Thanks for your comment. By the time you read this, you will already have decided what to do. I imagine your son is fine and I hope he is. I think perhaps it’s a good idea to have a talk with him and his doctor about why he doesn’t want to take the chewies. And perhaps find a way to help him sleep better that he feels comfortable with. And of course, keep pills safely locked away where he cant get to them.
      All the best

  • I’ve been taking small doses for a couple months now and then stopped for about a week bc it didn’t seem to work. then on a whim 3 nights ago I took 30mg (3 10mg tablets) and did so for the next two nights but it still took about 45 minutes to fall asleep, then tonight I took 50mg to try to fall asleep faster and after a half hour still not feeling the effects but I guess I should stop again because it doesn’t help much?

    • Hi Dan
      Thanks for your comment. It’s a common hope that taking more melatonin will have a better effect, but it’s usually not the case. I think if you haven’t had good results with the quantities you’ve taken, as you already worked out – it’s not going to work for you at all.

  • Hi Ethan,
    I’m a night shift worker. I have no trouble falling asleep after a shift but find I can’t get more than 5 hours sleep. Am interested in melatonin but unsure of timing. Would I take it after waking aiming to get another 3 hours sleep but not feel groggy or take it before going to sleep to help get the full 8 hours of (day) sleep? When I’m not on night shift I have no trouble sleeping.

    • Hi Sarah
      Thanks for your comment. You would take it before you went to sleep after your shift, or in the evening of your non-shift day if you had problems sleeping at normal times (which you don’t). But I wouldn’t take it after your 5 hour sleep.

  • I take anywhere from 10mg to 70mg or more every night and experience no side affect. I’m almost positive you could never take enough of the stuff to be honest

    • Hi Collin
      Thanks for your comment. I know that it’s often suggested that no amount of melatonin will do you great harm, and there are many anecdotal stories of people taking vast quantities and being fine – at least for now. My opinion though is that there’s no need at all to take anything like the amount you do. If it’s going to work, it will work in far smaller doses.

  • Hey Ethan,

    So I’ve heard mixed reviews about giving children melatonin. We talked to our pediatrician, who suggested it. I’ve got one with Autism & one with a sensory processing disorder. Nighttime is a nightmare, as you can imagine. One takes 0.5mg and the other takes 0.25 then another 0.25 if that doesn’t work. I hate medicating them both, but I figure it’s better than the prescription Clonidine (what one of my kids was taking for sleep).

    Anything you’ve heard about the affect of long term use of melatonin in children? (I have a boy & girl?) I’ve read conflicting research/theories of hormone imbalances, especially in girls. Although I feel like both are taking a fairly low dose. Our pedia also said that kids with Autism usually aren’t even producing enough melatonin anyways.

    Any thoughts?


    • Hi Ali
      Thanks for your comment. I can understand your concerns, as there is an on-going debate about the long-term effects of giving kids melatonin and the effects it can have on the onset of puberty for example. And I’ve also seen suggestions that, as you say, it can be helpful for kids with melatonin.
      I think the best thing is to keep working with your doctor, as they are the medical expert at the end of the day, but also keep yourself informed of developments in the research world around melatonin. It’s still something which isn’t completely understood in terms of the long-term effects of long-term use, so it’s likely over the coming years more will be known.
      I would also focus hard on trying to help them sleep using as many natural techniques as possible. Ideally, the melatonin wouldn’t be used long-term and their sleep patters would be stabilized through natural means. I understand this can be difficult to achieve, but I think it’s important to keep on it and keep trying.

  • I have a real sleeping problem, up all night doing nothing, but lay in bed with or without music trying to catch a nap, at least. but I’ve taken 3, 3mg of Melatonin before (at once), before bed but no drowsiness or sleepiness hit me. June 5th, 16 (tonight) I took 4 pills (at once) of the same mg. hours later, nothing but hunger has striked so i got something light to eat, which now keeps me up cuz I’m eating. If i take 5+ would it help me actually get sleep, or is it bad to be taking so many at once? I’ve taken X bars which i slept like a baby in a crib all night, seemed to help me better than this OTC doctor recommended stuff. i just want sleep, i hate life!):

    • Hi E-Z G
      Thanks for your comment. Sorry to hear you’ve been having such bad problems sleeping and are feeling upset because of it. It’s understandable that a lack of sleep can make you feel bad generally.
      If the melatonin didn’t work for you at those doses, it’s very unlikely to help if you keep taking more. It just doesn’t work that way. I would perhaps look at trying a different type of otc sleep aid. I’d also talk to a doctor to get some advice and support – perhaps they can also help you with how you’re feeling about life generally at the moment.
      I also wrote an article recently about how I personally overcame insomnia. Have a read of that as you might find it helpful.

  • I’ve been taking at least 36to54 ml. each night. I have had absolutely horrible headaches daily. Could this have anything to do with taking it?

    • Hi Sherry
      It’s possible, yes. I would stop taking it for a week and see if the headaches clear up. If not, then ask your doctor to check you out to try and find out what’s causing them.

  • I am taking 5mg of melatonin, which does not help me at all. I have started taking Ambien, 5mg. Is this safe to take every night. I have a friend who has been taking 10mg a night for years and is fine.

    • Hi Pat
      Thanks for your comment. Do you mean is it safe to take the combination of the ambien and melatonin every night? As far as I’m aware, they are generally considered safe to take together. However, you may feel the effects even more strongly, meaning you should be careful what you do after taking them. To be on the safe side, I’d consult your prescribing doctor to get their advice.