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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536 CommentsLeave a comment

  • Hi I’m curious I normally take 2 fast dissolving tablets before I go to bed every night and I’m wondering if that is bad. It says on the bottle that it is 6mg per tablet I believe. Any idea on how much you’d recommend on taking? I use to only take one but it never helped and normally two helps but I also sleep in really late.

    • Hi Alyssa
      Thanks for your comment. Usually for most people 12mg would be way more than necessary to help with sleep. But if you do feel it helps, but then causes you to sleep too much, that’s another issue to think about too. If you’re not sure about dosage, I’d speak to your doctor about it to get their advice. Even if it’s available over the counter in your country, it’s still worth checking with them.

  • Hi
    I took 15 mg total (3 gummies) of melatonin last night at about 4 am because I always have trouble sleeping, although i’ve never taken this high of a dosage before. The next day, I was having nausea all day it seemed like and just felt very groggy and not myself. Was having mood swings all day as well. I was just wondering if these symptoms were normal? Or should i be worried for something else, and that these symptoms are not usual for 15mg of melatonin?

    • Hi Lauren
      Thanks for your comment. It’s very possible it was connected to the melatonin, though not certain of course. But if you continue feeling this way 2 days or more later, then it could be something else.

  • I have had trouble sleeping every night. This has only been the last 5 years. At a Drs. Appointment for chronic pain, my Dr. Told me he takes 2 Melatonin pills and magnesium. I tried this and it seemed to help for awhile, then stopped helping. I normally take a 2 mg Xanax also at night. I wake up multiple times during the night and take 5-10 mg again of melatonin. It helps about half the time. I added benedryl to my regimen, but I either feel groggy all day or there is no recognizable effect. I fall asleep during day that doesn’t seem to impact my sleep at night.

  • one dr suggested I take 5 to 10mg of melatonin.. I take only 1/2 of the 5 mg..and it does help me sleep , the only thing is i feel so exhausted the next day . for instance, last nite i did not take any melatonin and i feel much more alert today. I assume this means i am taking too much? thanks

  • I was told by a RN that our Local Hospitals give 10 mg to Patients at night so I started taking 10 each night for 4-5 years now. Prior to that I had only taken 5 msg but had done that for years also. I should note that I am an odd case as my Sleep Dr says that I not only have severe insomnia, but he also thinks I have a mild case of narcolepsy! He has tried everything on me and just grins & shakes his head and says there is really no more he knows of that can be done. Years ago he told me that what he thought was the exact medicine I was needing was not yet approved by the FDA,… and we waited through years for it to be approved. It never has been but it IS approved in England. After another year and it still not being approved of here in the States he said he figured something undesirable or ineffective had happened in England and this led to still not getting approval in USA. BUT, after checking he found out that it was still being dispensed in England! So, whatever it is (I don’t think he ever told me) it’s still a mystery why it’s not been approved of here yet. He currently prescribes all this for me to sleep: 900 mg of Gabepentin, 200 mg of Trazadone, 30 mg of Mirtazapine, & I take the 10 mg of Melatonin (Dr is aware of that),…..and 1/2 or more of my nights I STILL can fall asleep until 5:30-6:30 am,…and lots of nights I never sleep at all and don’t crash during the day! It’s so frustrating! He also has me taking 20 mg of adderall & 200 mg of Modafinil first thing in the morning to address the narcolepsy. I’m also supposed to take another Modafil after lunch but I never feel I need it and I rarely take that. I’m sure you wonder if those morning Ned’s might be causing the insomnia at night, but it’s not because Most the time I only take 1 of the Adderall, and numerous times I’ve taken none of the morning mess to see if that might allow me to sleep that night….but I STILL have the same BIG bout with the insomnia that night. Those morning Ned’s seem to be making no contribution to my insomnia. NOW, I just read an article that the Gabepentin impairs the Brain to create the new synapses it needs to be doing , SO I’ve just quit taking that because that article frightened me. Last night and the night before I slept only 2 hours each night. Any wisdom or suggestions you might could give me about the use of the 10 mg of Melatonin I’ve been taking for so long now,…. or about any of the other Ned’s,….or just any new suggestions on how to treat this insomnia. I’m 67 years old and in pretty good shape and with no major health issues other than severe Sleep Apnea (I use one of the expensive Mouth Pieces because after years of trying, I never was able to sleep in a CPAP Mask. Sleep Studies showed that even though the mouth piece really makes a huge difference for me that I still, even with it, rarely can delve into the deep REM stage of sleep. [I know. I’m a MESS! 😉]

    Any wisdom you can give me will be greatly appreciated! Thank you!

    • Hi David
      Thanks for your comment and for sharing your experience. It sounds like you’ve really had lot of sleep problems there, and have quite a complex case with various sleep disorders and a range of medication. It’s not my place to give advice about your prescribed medication, especially if it’s coming from a sleep doctor, who will know your case well. But perhaps if you feel that the medication is too much, or not working, it’s maybe worth asking them if it’s really necessary and/or the right combination of meds. If you’re taking so many meds and still not sleeping, then perhaps there’s an alternative that can be tried. And sometimes in complex situations, it’s worth getting a second opinion. Is this something you could do?

    • Hello,
      I read your comment and I’m a little concerned what your Dr. Has prescribed you. Trazadone is for anxiety, Depression, Chronic pain, and ADHD. Now why would he prescribe you Mirtazapine ? That’s for Depression. But Trazadone is an anti depressant… Adderall is for ADHD. But Trazadone helps with ADHD… So my question is this. Why is your Dr. Over prescribing you these drugs ? I’m concerned because this is what some Dr.s do. They did it to my mom, grandparents, friends. Anyways I’m just looking out for you. I can’t stand to see patients being taken over by addictive man made pills. It’s madness. Food for thought. Be careful my friend. Do a little more research and you’ll find the facts. If you don’t know what you’re taking, look it up.😊

  • My doctor recommended these.
    Right after handing me my anti depressent script… Lol.
    Thank you for posting this i wasnt informed on any side effects or warnings.

  • Hi, I’m wondering, if I were to use some DR. Fresh Melatonin Strips that I got 2 or more years ago and that I believe are expired, would there be negative effects and is it safe?

  • my mom takes 15 melatonin and they are 10mg and she sometimes sleeps and sometimes does not she takes them every two or three hours and when she does she never sleeps my stepdad takes them away from her and she sneaks and buys some more I take one with a full cup of zzz quill and I two hours later I am out like a light but she has trouble sleeping so what can I do I can not tell my stepdad because he will take them away from the both us and won’t let us have any and so what can I do

    • Hi Jackie
      Thanks for your comment. This sounds like quite a complicated situation, so I can understand you’d be worried. A key point is that your mum is using them in a way that’s not helpful, and probably not healthy. Have you spoken to her about why she feels the need to take them so often during the day? Perhaps you could suggest she speaks to her doctor about her sleep problems to get some advice and support. And is there anyone else in the family you feel you can talk to about this situation, and how it’s making you feel?

  • I’ve been taking 20 mg of melatonin the past few days and it seems to be working however I’ve been experiencing discomfort in my stomach, should I stop taking such a high dosage?

    • Hi there
      I’d definitely reduce the dose unless you’ve been prescribed that much. But it may be that you’ll still react badly to it, so it’s probably a good idea to check with your primary care doctor before continuing it.

  • what happens if a 19 month toddler takes 40mg of adult melatonin? Just got a phone call from a friend and they informed me that there grandbaby took 40mg of gummy bear melatonin. The baby is hyper, not sleepy, I informed them to call the hotline for poison control and monitor the baby q30 minutes, also give the baby some milk to coat the stomach.

    • Hi
      Sorry I wasn’t able to reply sooner – I get a lot of comments, so can’t always respond in hours. Hopefully your friend’s baby was okay. You did the right thing advising them to call for help.

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