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

melatonin overdoseMelatonin tablets are generally seen as ‘safe’ sleeping pills by most consumers, doctors and scientists. This is largely because Melatonin is a natural hormone which your own body produces.

But is it completely fool-proof safe, or can you overdose on Melatonin? And what kind of side effects can you expect with a normal or high dose?

Technically anything over the recommended dosage can be considered an overdose. The problem is though, Melatonin doesn’t really have an official recommended dosage.

That said, most doctors and researchers say you should take no more than 5mg a day. And preferably less for most sleep problems.

This was also the standard dose we found in most brands during our review of over the counter sleep aids.

So we will look at what might happen if you take more than that dosage. And what symptoms you might expect from a Melatonin overdose.

And if you are interested in more background information, have a read of our article examining how well Melatonin works.

Surely there must be a recommended dosage of Melatonin?

There really isn’t a standard recommended dose of Melatonin at the moment. And interestingly most brands sell it in quantities far higher than the body actually produces.

Melatonin is marketed and sold as a dietary supplement or natural remedy. So it has not undergone the rigorous testing of organizations such as the Food and Drugs Administration in the United States. And therefore there is no central body to say exactly how many milligrams you should take.

So you are left to trust the advice of anyone else who speaks up on the matter. Some good advice from the University of Maryland Medical Center for example 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 go on to 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. And if that dosage of Melatonin 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 if so, how much to take.

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 is safe at a dose of 5mg for up to 2 years. Although on another section of their website they say it’s best not to take it for more than 2 months.

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 is considered a Melatonin overdose and what might happen?seek help if you take a melatonin overdose

So what happens if you have a bottle of Melatonin 3mg pills which tell you to take one before bed. But you decide to take two or three times that amount, or even more?

Well according to most research, you shouldn’t be in any great danger if you take a small Melatonin overdose.

And in fact it is 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 is 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 the more likely it is that you will experience a ‘Melatonin hangover’ the next day. This is because the Melatonin effectively tells your body ‘more melatonin means it’s time for sleep’.

So when you take it in the middle of the night, your body clock is being pushed forwards. If you are very drowsy the next day then you run a higher risk of having an accident which could harm you or others.

There is no medical advice or research stating what would happen if you took a very high dose of Melatonin. It is highly recommended that you do not consider doing this. At the very least you are likely to experience some unpleasant side effects.

Whatever dose you take, if you start experiencing side effects, then you should seek medical attention.

And if you do take a large Melatonin overdose, intentionally or by accident, it is advisable to seek emergency medical attention immediately. In the US this could be an emergency room or poison control center.

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

Possible Melatonin side effects

1. Daytime drowsiness

Ok you might laugh, but one side effect is of course drowsiness. Yes, it’s like saying on a bottle of milk ‘warning contains dairy products’. But the point is, if you take Melatonin at the wrong time you can end up being drowsy during the day. You are then a risk if driving or operating heavy machinery for example.

2. Hormonal changes

Again this sounds obvious. You are 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.

But it can also reduce the sex drives of both men and women. As well as interfere with women’s ovulation and men’s sperm count. So if you are trying to get pregnant, Melatonin probably won’t help.

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. People who suffer from any kind of depressive illness should not take Melatonin.

4. Hallucinations, paranoia and disorientation

More likely if you take a Melatonin overdose, you may experience hallucinations, delusions, disorientation, confusion and paranoia. These are side effects not to be taken lightly as they can be very disturbing.

5. Increase in vivid dreams and unusual sleep behavior

You may find you have very vivid dreams. It can also increase the possibility of other events such as sleep walking and nightmares.

6. Physiological effects

Melatonin has been found to have several effects on the body. This includes lowering blood pressure, or even raising it if you are 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 cramps and pains, and 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 therefore not use Melatonin as not enough is known about its safety at this time.

10. Serious allergic reaction including rashes and swelling

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 definitely 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 is 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 also interact with other drugs. So you should consult a doctor if you are taking, or planning on taking any of the following:

  • Blood thinners, such as Warfarin or Heparin.
  • Blood pressure medicine, like 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 a  extensive list of exact medications which can interact with Melatonin, have a look at the Webmd article here.


So can you overdose on Melatonin? It would appear that the answer is most definitely yes. But what might happen will depend on many different factors. As with most substances, two people might experience very different symptoms even when taking the same medication.

You can see that there a long list of potentially harmful effects of taking Melatonin. But there are also additional risks for certain people.

So we recommend you stick to the various recommended doses that major organizations such as the Mayoclinic offer.

But first and foremost speak to a doctor to check that it will be totally safe for you. You can also then get clear advice on what dose you should take and how long for.

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

320 CommentsLeave a comment

    • Hi
      Hopefully you’ll be ok. I suspect the cocaine isn’t exactly going to work well In tandem with a sleep aid. To be honest, it’s a fairly pointless cocktail you made for yourself, and I would be having a think about the point of taking these substances.

  • My husband has been taking melatonin for about a month now and he started with hallucinations, delusions, disorientation, confusion and paranoia. Will this go away now that he has stopped taking it, and how long will this last?

    • Hi Jeanne
      Thanks for your comment. Sorry to hear your husband reacted in that way. I imagine he will get better pretty quickly. If not, definitely keep in close contact with your doctor about it.

  • Hello I’m 16 and I have been taking 10mg everyday of melatonin for the past 4-5 years. I’m really curious too know if that’s kinda bad or not. 2nd is it possible to build a tolerance for it because it doesn’t work any more and I still take it anyway.

    • Hi Noah
      Thanks for your comment. I think both points you mention lead to the same course of action, which is to speak with your doctor and family about it. It is a long time to be taking melatonin, and if it doesn’t work, why continue? I think it might help you understand why you’ve continued taking it if you chat to your doctor about it. And if they are the one prescribing it, I would want to know if they really think it’s necessary any more.

  • I gave my 8 year old little sister a 5mg tablet of melatonin (the usual amount she takes because she has ADHD) without knowing that my father already gave her one. So in total she had 10 mg, should I just let her go to sleep? Do you think she will be fine?

    • Hi Nikki
      Sorry I wasn’t in time to reply to you. Unfortunately I don’t always get round to replying to comments until a few days later. I imagine your sister was fine, but if this kind of thing happens again, I would tell your dad asap, and also ask a doctor for their advice.

  • i sorta took 60 2mg pills, trying to commit suicide, and idk if i might die or not rn, like im scared cus i regret it
    whats going to happen?

    • Hi Adam
      Sorry it’s taken so long to reply to your comment. I imagine by now you know the answer to your question. I’m also sorry to hear that you were feeling so low at that time. It’s positive that you regretted it though as it says that you still do have a will to live. I hope you have someone you can talk to about what’s been going on in your life. I also recommend asking for some professional help, through your doctor would be a good starting point.

  • 4 yr old took 6 tablets of 3 mg Melatonin and was sleepy 3 hrs later.. Is it ok to let her sleep? Just found out that she had taken them

    • Hi Mel
      It’s not my place to give advice on that, I’m afraid. I would call your doctor to check and get some medical advice based on her medical history.

  • I took 45mg… 15 melatonin 3mg pills… Will I die? Lol. I’m 16. And 10pills didn’t work, so I tried 15. I’m feeling the effects, but am I in danger???

    • Hi Zach
      Thanks for your comment. By the time you read this you will probably already have the answer to your first question. Obviously I don’t know what led you to decide to take so many pills, but if it was to try to sleep better, then it’s important to understand that higher doses of melatonin don’t necessarily work better than lower doses. And in fact, if 30mg didn’t help you sleep, 45mg is unlikely to. My advice would be not to take so many again, as it just won’t do what you want it to do. If you need help with your sleep, I’d speak to your doctor about it, and also your family. As for your second question, I think you need to be careful taking large quantities of any pills. Again, I’d speak to your doctor about the amount you took, why you took it and see if they can provide some better ideas to help you.

  • I have an 8 yr old who has been put on melatonin by his pead, .75 of a ml, however, 5 hours after taking it, he is still wide awake and unable to get to sleep?

    • Hi Robyn
      Thanks for your comment. Unfortunately melatonin doesn’t work perfectly as a sleep aid for everyone. It depends on many different things, with one of the main factors being the root cause of the sleep problems. I’d have a read of this article about how melatonin works and it will give you some more information about it, which should help you understand when and how it works.

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