Melatonin side effects

Melatonin is a good natural sleeping supplement that many with sleeping problems find useful, but being a hormone, you always need to use it with caution. Ever since it was categorized as a dietary supplement in the early 90s and allowed to be sold over the counter, melatonin has never been reported to produce any serious side effects.

Obviously, nearly twenty years of widespread usage is quite long to validate that it’s fairly safe, but all the same, it should never be taken in large doses for a prolonged period. Certain people may react adversely to it more than others. So far, most studies have found melatonin in low dosages to be safe, for at least for up to 3 months of continuous use.

If you are depressed or undergoing psychological/emotional problems, melatonin may make them worse, especially if you take it at high doses. It can cause a heavy feeling of mental dullness throughout the day, even if it doesn’t translate into sleep for you. Melatonin may help with some types of insomnia, but unfortunately not all types.

melatonin phase response curveThis mental fog during daytime may have to do with the effect of the supplemental melatonin affecting physiology outside of the melatonin phase response curve (PRC). Phase response curve is the shifting of phases in a circadian rhythm affected by a stimulus or catalyst (melatonin here).

Therefore, remember to only take melatonin just before bedtime at night, and even if you still cannot sleep for hours, do not take additional doses nearer to the morning, or you could end up feeling pretty gray, the next day.

Aside from mental fog, other side effects like drowsiness, slow heartbeat, nausea, and headaches have been reported. Besides that, excess melatonin can cause nightmares during sleeping. Here is some of my advice on melatonin dosage.

Those who should not be taking melatonin include:

  • Depressed people/people with mental illness
  • Pregnant women/women trying to conceive
  • Children
  • People with cancer
  • People on steroids
  • People with severe allergies
  • People with leukemia/lymphoma

Aside from the side effects, a drawback of prolonged excess melatonin supplementation is the possibility of depressing your own pineal gland’s production and reducing its ability to secrete melatonin on its own. That is why it is best to periodically go off your melatonin supplements even if you never overdose on it. Also remember, if stopping melatonin after long term use, it is best to taper off the dosage to avoid with rebound insomnia.

41 Responses to “Melatonin side effects”

  1. This explains my prolonged (3 days) headache! And the nightmares I’ve been having. All seem to line up with the introduction of melatonin… I think I’ll stop using this stuffs, see if my symptoms go away..
    Thanks for the info.

  2. Hi Vanessa,
    You might be taking a dose that is too high for your own tolerance level. Melatonin is generally very safe though. I’ve been taking melatonin for a long time without any untoward side effects.

  3. Melatonin always gives me restless leg syndrome. This is not a well known side effect but it is caused by the changes in the brain with dopamine

  4. i still cannot sleep w/ melatonin even i already doubled the dose.
    it just gave me headache

  5. @ Brooke,
    Headaches are one of the most common melatonin side effects reported, and that is usually due to taking too much of it. Melatonin is not really effective if your sleeping problems are not caused by a lack of melatonin (normally older people have low levels of it). It can help in a small way by increasing your drowsiness, but not much more.

  6. Following up with what Crystal mentioned, I took triple strength the other night and didn’t sleep because of RLS. Is this side effect documented at all?

  7. Hi Jess,
    RLS does not seem to be a common side effect of melatonin overdose, and it’s certainly rare. I’ve never read of this anywhere. Just to relate my own experience, I’ve taken fairly large doses before (about 10 mg), and the most I’ve had was a headache, but I suppose this does vary from person to person. It’s not advisable to be taking such large doses though, because more is oftentimes not really better.

  8. Has anyone experiencing headaches either taken their blood pressure or had it checked for them during the onset (or as close as possible to the onset) if r their headaches? If so, was the blood pressure found to be elevated?

  9. Has anyone suffered night sweats from melatonin? I’ve been getting them pretty bad, and wondering if it’s a side effect from it…

  10. I have been seeing dots and having what seem to be pretty serious migraine symptoms and sometimes get dizzy and cross eyed , all started after taking melatonin.

  11. I used it one time and woke up with a dark spot half an inch by half an inch) on my hand. It has been four days and it’s still there! My mom took it the day after me and also woke up with a dark spot on the SAME hand! Anyone else get dark spots from taking Melatonin??

  12. My boyfriend takes it and lately he’s been getting night sweats and uncontrollable shaking as well. Like out of nowhere his head will shake back and forth. He takes it every night. Is this a side effect of it as well?

  13. I am using stresnil 0.5 from 2 years for Insomnia (contents- alprazolam 0.5 and melatonin 3 mg). I dont have any side effects. can i continue this??

  14. If you’ve read the info above, you’ll realize that Melatonin has various possible side affects, including headache. Melatonin is a hormone created by your body. If your body lacks this hormone, it will affect your sleeping patterns. If you have problems sleeping and a lack of melatonin is not the issue, than you want to look into another solution. Taking melatonin without reason can possibly lead to worse side affects as stated above.

  15. You are saying that melatonin should not be used for people with cancer whilst the are articles where it is shown to help in certain cancers…what s your say

  16. @ Pr
    Melatonin may also affect other hormone levels, so it should be used with caution. It helps to prevent cancers, but when certain cancers are in the advanced stage, you should be careful with things like hormones, and melatonin is a hormone after all. If you read deeper, these certain cancers referred to are immune system cancers like leukemia.

  17. I absolutely love Melatonin and swear by it. I was completely addicted to benzodiazepines to the point where they simply stopped working. No sleep medication would work either after that and the withdrawal was a complete nightmare. I was awake and looking at the clock trying to calculate how much sleep I would get if I could fall asleep by a certain time. Then someone suggested that I try Melatonin. At first I dismissed the idea because it was “natural” and I did not think that it could be nearly as effective as a prescription drug but I was desperate and I tried it. I took 60mg the first 2 or 3 nights and I was surprised when I woke up and realized that I had actually slept through the night! I have been using it every since; it’s been about a year and a half… It saved my life because broken sleep was like having no sleep and I did not want to go back to prescription medication for fear of withdrawal. Melatonin works for me in higher doses.

  18. I have been taking melatonin for almost ten years to help me sleep during my long midnight shift. Before that, nothing seemed to help. The only drawback is I must have built up a tolerance as I must take 3 tablets to get the same effects I used to get with one.

  19. @ M. Fluker

    Yes, melatonin resistance can develop quite easily, which is why it’s always advisable to skip melatonin periodically, and only stay with the lowest possible dose.

  20. I have been diagnosed with depression. when I told my doctor and therapist about having insomia problems, they both recomended Melatonin. I went from taking 2 sleeping pills every night to taking 1 3mg melatonin pill maybe 2 times a week. It makes me feel so much better. No drozy side effect and actually have nights where i dont need anything to help me fall asleep. I would have never thought about my body not having enough melatonin in it. But I seriously would recommend talking to health care provider before taking it incase it is something else causeing the sleeping problems.

  21. I was taking this stuff and had no idea it was causing severe migraines I have epilepsy severe insomnia anxiety and take celexa. The headaches were severe and nothing helped.my insomnia did not improve and I was unable to even focus I would forget everything I mean would literally forget what I was talking about in mid sentence had severe panic attacks was seeing things like my mind was playing tricks on me I recently suffered a grandmal seizure and have not gotten any better with the inability to focus I thought something was going on with my brain something worse than before I am so happy I read you guys side effects I had no clue melatonin could do this I had only recently started taking it since prescription sleep meds absolutely do not work for me omg I am soooo relieved to find this website you guys just gave me a huge weight lifted off my shoulders and now hopefully no more migraines…..Thank you!!

  22. Many here say to be careful not to take too much. I just bought a bottle yesterday of 3mg pills. Is 3mg ok?

  23. @ Don
    3 mg is pretty much the standard dose sold by most brands these days. I think it should be ok, or else, you can break the pill into two parts. Some brands actually suggest doing that on the label.

  24. I am a long term insomniac who was on prescription sleep aids for over a year. I started taking melatonin about six months ago, and it is every bit as effective as a heavy duty prescription sleeping pill for me. Started at 3 mg, but have cut pills in half to 1.5 for most of the time and it WORKS. 20 minutes to a half hour after taking, I MUST hit the sack. I have a sneaking suspicion that although I’m an old fart, I have been melatonin deficient for many years. If it works on anyone else like it works on me – it’s no pill to fool with.. do NOT take this stuff if you aren’t absolutely sure you have 8 hours of zero responsibility.. I wouldn’t dream of driving or operating machinery or even walking anywhere after taking this stuff, even the 1.5 mg. Unisom used to help a little, the other OTC sleep aid not at all, but this stuff is lights out for me. Might even consider finding 1mg pills for lower dose still.

  25. @ John,
    Thanks for sharing your experiences :)

  26. this is not good for kids do not give it to kids

  27. I have a child who is 12 has ADD and our pediatrician recommended melatonin for him at bedtime. He has a terrible time slowing down to go to sleep, his mind races and he cannot fall asleep. He takes 3 mg of melatonin and it helps him to fall asleep. I am concerned about long term use though but can’t find much information on it for children.

  28. So, say one were to take like 9 mg in a single dose… How long would it take to clear from the system. The first 15 hours was fine, but I was sleeping 2 hours at a time, but here I am at about 30 hours after taking it and I feel like I drank too much (without drinking). What is a good way to balance out melatonin without sleeping?

  29. I have taken Melatonin in times past because people said it was good for insomnia, but in the tiny doses it says to take, it would only maybe make me mildly drowsy and have weird thoughts. Or I would even be in a trance-like state and have weird waking dreams.
    But a friend of mine whom I trust for info on herbs and nutrition said she has to use more than the suggested dose (sometimes up to 10 pills) to get past that stage and then, it helps her really sleep.
    I tried that, and was amazed at how well it worked. When I used it, though, I was most of the time combining it with benadryl. The first night I didn’t use benadryl with it, it still worked great.
    I was even gradually reducing dosage hoping my body would kick in a little of its own. That worked great on benadryl too, but without the benadryl, it took only 2 nights for it not to do much at all. And here I had it knocked down all the way to 5 pills a night, too. I took four, and was wide awake with weird trains of thought. So I popped another one, and nothing. No benadryl then. That was last night. So I finally gave in, got up and took some benadryl and fell asleep just as it was starting to get light.
    Now, if it worked for awhile at a high dose, and as I reduce, it doesn’t work, doesn’t that mean my insomnia must be because my body must make next to nothing in the way of its own melatonin, so I should keep up with the insane high dosages? My melatonin is 3 mg per pill. And what do you do in the times when you are giving your body that rest between supplements to the tune of a month or so? Go without sleep? Nothing else works for me on a regular basis except for Amitryptiline which is overkill at any dosage for me. Benadryl for two or three nights in a row might work, but only for 4 hours. Then what? It takes up to 2 hours for it to kick in when I take it so I need ten- to twelve-hour nights for that.
    I notice someone up a ways in these comments wrote in that she takes it in 60 mg amounts. I think I might be a bit like her. i envy those who can really benefit from 3-5 mg a night.

  30. I have severe alcoholism. Benzos are just a swap that makes me towards the end of the day….want to drink more. They only help with the anxiety about drinking. I take melatonin and it works rather well. I can manage to pick up the bottle only twice a week(still working on that). I was taking 3-6 mg a night. A buddy of mine was shocked because he takes 1 mg. I recently was at the drug store and found a 10 mg time released. Being the addict that I am I purchased it. (figured it was better than filling my lorazepam). I would really suggest trying melatonin to anyone suffering from alochol/benzo dependance after and during withdrawal. But my question is: Being OTC if I can’t sleep which bottle do I pick up? Vodka or Melatonin? Now that I have found the 10 mg pills, and let’s say i take 3– That is 30x what my buddy takes. If i take 20 mg I feel hungover the next morning which for the alcholic means not working and drinking. So where from 3mg-20mg do i find the proper dosage. If I took 20mg of lorazepam….. I also saw no comments about time released melatonin.

  31. I know someone that take 10 pills of melatonin a night. each pill is 10mg. Im just wondering about the side effects. i realize it isnt safe. Could nausea and fainting be a side effect?

  32. @ Holly

    Yes, nausea and fainting could be side effects; individuals react differently. 100 mg per night definitely sounds very high. One drawback is you might build up resistance, and therefore have to keep on increasing your dosage.

  33. I’ve been taking melatonin for almost 4 months now. I’m just wondering how many or how much I can take. I took a 3mg and I slept for an hour and woke back up. Now its almost been 3 and a half hours and I’m wide awake. Is it okay for me to take another 3mg pill?

  34. Hi Courtney,
    In my opinion it should be ok especially if it’s still some way to go before dawn, and if so far in the past 4 months your body appears to tolerate melatonin well. Sometimes, if I wake up inadvertently in the middle of the night, I do take an additional pill and I’m soon asleep.

  35. I started taking Melatonin about 6 months ago and now swear by it. But I didn’t notice it helping immediately. I did feel foggy the next day, but. I think it was a week of taking 3-6mg (each night) before I had a full night’s sleep. I never used to dream (or remember my dreams, as they say), but now I have vivid dreams nightly. The only negative side effect I’ve noticed is the headaches. Now, I don’t have to take it every night, but, it helps if I have a lot on my mind.

  36. I’m in my late 50’s and have tken melatonin every night for years. Worked beautifully. Starting last week it stopped working as well, although I was still getting drowsy, so I upped the dosage. Today I woke up with all the side effects–nausea, foggy brain, sluggish. I am going to stop it entirely and use it only for “emergencies”.

  37. I have been having lots of RLS since I started taking this drug. I will be discontinuing after reading that other people have been having similar effects. I was positive it had to do with Melatonin, but wanted to make absolute sure.

    On a good note. It did help me go to bed. On a bad note, I have RLS very badly now and hopefully it goes away once it gets out of my system.

  38. I have been OD on it apparently as I bought 5mg instead of the 3mg. So maybe if I only take 1/5th of the pill will I feel better.

  39. Bonnie Gabriel on March 17th, 2012 at 2:29 pm

    I started taking 20 mg of melatonin – the capsules were 10 so I took 2 as I was not sleeping at all. I had looked on computer and a site said up to 20 was safe. I am only 130 pounds so this may also be affecting me as I feel a little foggy and sluggish. I should have done more research before taking it. It still did not really help me sleep that much, perhaps a little. I guess I should cut back to the 3-6 mg per day? Thanks

  40. I was addicted to sleeping pills for three years until they stopped working..now I take the dissolve under the tongue pills of 10 mg each, Swiss brand from Walmart for approx. $15.00 and I take two to total 20 mg a nite and barely get 6 hours and a bit of sleep…have always been an insomniac from childhood…thinking of taking even more….I have no side effects except perhaps the hot flashes, tho am 60 yrs. old, have been hot flashing for almost 15 yrs now anyway…!!!…yeah and when I do not take them I do not sleep at all…so what the heck…I take them every nite for approx. 4 mo.s now….kind of addicted to them…keep the bottle by my bed and pop a couple before I roll in…do not know how else to get any decent sleep and want even more but avoid starting to take more than the 20 mg……any suggestions or warnings…??? Please and thankyou kindly….regards…me…!

  41. @ Ruth,

    Just my opinion, I also pop them almost every night, for years now, and I’ve never varied the dose much. It will always be either 3 mg or sometimes 6 mg. If you find them helping you to sleep, I think it is great. I would not recommend going more than what you’re taking and try to go some nights without them, because 20 mg seems to be quite a heavy dose and the downside I can think of is that you will make yourself less sensitive to melatonin’s effects. Thus, you may find yourself needing a larger and larger dose as time goes by, and that’s not good.