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?
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
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 webmd.com 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.