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 of 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.



16 Responses to “Can You Overdose On Melatonin? A Look At The Side Effects And Dosage”

  1. Violeta Vega says:

    Hi Ethan,

    This is a great piece of information about the effects of Melatonin. Especially because my boyfriend and I have problems with sleeping, and we are also considering having a baby. We are not very keen to take pills, but we were considering trying Melatonin.

    Now that I read your article, I might not use it. But still it was good to know more about this hormone.

    thank you, and keep writing!

    • Thanks for your comment and compliments Violeta. Life can be definitely be complicated when you have two aims which might conflict. So I am glad you are a little more aware now of the possible side effects Melatonin can have. It’s up to you and your boyfriend to balance the risks or either taking Melatonin or continuing to suffer the effects of sleep deprivation.

      If you don’t want to take pills, there are natural ways to work on your sleep problems. I highly recommend you have a look at our extensive section regarding sleep hygiene. I know many people feel they’ve heard it all before. So that’s why we have tried to compile a much larger resource than you might normally come across on the internet.

      And on a lighter note, you may also find the following article interesting. I’m sure you can guess from the title why…

      Why Do Men Fall Asleep After Sex? – The Natural Insomnia Cure

    • Byron says:

      Is the diarrhea side effect of Melatonin due to the presence of Magnesium in the tablet?


      • Hi Byron

        To be perfectly honest, I’m not sure. After reading your comment I had a look at the research and there is nothing I can find which pinpoints it one way or the other. Magnesium, as you obviously know, is known to sometimes cause diarrhea when used as an ingredient in pills (as in all otc melatonin pills). So you may be right, but I can’t find anything to answer your question definitively.


  2. RSN says:

    can you cite your sources for the risks stated. I am having a tough time rationalizing and understanding risks for IBD listed above from taking melatonin when I read where melatonin has been researched for various IBD.

    • Hi

      I’m assuming you’re talking about some of the research in the last decade which has shown that melatonin may help people with a variety of gastrointestinal problems. I don’t discuss that above because the article was intended to be about people taking melatonin for sleep-related problems.

      I had a look after seeing your comment and from the research it seems that the current situation is still that more studies are needed to confirm whether or not Melatonin is an appropriate treatment for gastrointestinal problems. There is a good journal article about that here which you may find more helpful to read as it is specific to your topic. In addition this journal article might be useful to you.

  3. Kathy says:

    I have been taking 25mg each night. Having trouble sleeping since my husband died. I have not had any adverse side effects yet.

  4. Andrea says:

    What about melatonin for children? I have an eight year old that has been having problems falling asleep at night. Once she’s asleep she’s good but it’s just the general falling asleep she has problems with. Although last night she slept for 4 hours. Went to sleep at eight and was awake for the day at Midnite.

    • Hi Andrea

      You’re not alone in considering Melatonin as a sleep aid for kids. It is quite a controversial topic though, and one which I wrote about in this article. The idea being that I wanted to explore the reasons for and against giving Melatonin to children. You may find that useful.

  5. Joey says:

    I’ve been taking 40-60mg of melatonin nightly for the past five months after seeing a neurologist to help with my inability to sleep well on my own even though I get tired. He recommended I take around 5mg max, which did nothing to help me. I have CPAP machine, sleep in a dark room with no distractions and only the sound of a fan. It’s rather frustrating when I take as much as 60mg and still don’t even become the slightest bit drowsy.

    • Hi Joey

      Did you read the other article on Melatonin which discusses the situations/sleep disorders it’s most useful for? I assume you’ve had good medical advice, but it’s possible that melatonin just won’t help you, no matter what dosage you take. It’s not like most sleeping pills which are designed to relax you, or knock you out. It only works in certain circumstances, and even then not for everyone. So you may want to have another chat with a doctor if you still feel that you need something extra to help you sleep.

  6. Misty says:

    Melatonin made me sick! I was taking a low dose to help me sleep.. About a week after I started taking the pill, I started to get real dizzy while at work. Another week and I could barely function at work because the dizziness and constantly feeling like I was going to black out. Finally I went to my doctor only to find out he had no clue what was going on. I had to have an echocardiogram and wear a halter monitor for 24 hours. By the time they started all these tests, I had already stopped taking the melatonin. Slowly the dizziness went away on it’s own. All my tests came back fine, but I continued to suffer from lack of sleep. The doctor never confirmed that it was the melatonin, but it was the only new medication in my life. For the record, the doc never denied it was the melatonin either. Am I just a strange case?

    • Hi Misty

      Thanks for taking the time to share your story. The problem with testing sounds like something I’ve experienced – when you have tests done because of a medical problem, but you’ve already stopped doing whatever it was that you thought might be causing it. It makes it quite tricky to give you any firm answer much of the time, and probably the reason the doctor couldn’t confirm either way.
      It’s your choice whether to try it again – under medical guidance – but it sounds like you already know enough.
      I don’t think you’re necessarily a strange case, no! Dizziness etc is such a common symptom, with so many possible causes. It doesn’t mean you’re strange.
      I hope you don’t experience this again, with or without the melatonin.

  7. John says:

    I’ve taken sixty 10 milligram tablets in a span of 4 days. Hasn’t done anything for me.

    • Hi John

      That really is quite a lot. Can I ask why you decided to take so much? And if that much hasn’t done anything for you, then you can probably assume that no amount is going to work for you. Maybe have a word with your doctor to see what they recommend.

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