Written by Jill Zwarensteyn, Editor
This article was expert reviewed by Sleep Psychologist Katherine Hall.
Is it possible to overdose on melatonin? Can taking too much do harm?
Chances are if you’re asking this question — you’ve probably been experimenting with supplements to help you sleep.
Many people take melatonin to try and help themselves fall asleep faster or overcome the symptoms of jet lag. If you’ve been counting sheep for hours, it may be tempting to pop a few pills to get some sleep. If it still doesn’t work, you may start getting desperate and decide to take a couple more pills to knock yourself out.
Sound familiar? You may be wondering if this could lead to any potentially dangerous consequences. Keep reading to get the essential info on melatonin safety, side effects, and dosage.
Is Melatonin Safe?
Most people feel perfectly safe taking an over-the-counter supplement like this one for sleep. In fact, melatonin is one of the most popular sleep aids. Aside from insomnia and jet lag, other uses include headaches, cancer, tinnitus, Alzheimer’s, and protection from radiation.
Unlike most over-the-counter (OTC) products that come from plants, vitamins, and minerals, this one is a hormone that is produced naturally by the body and is linked to the circadian rhythm. Despite being considered a relatively safe supplement, OTC use has been banned for years in Japan, Australia, the U.K., and parts of the European Union. In these countries, the only way to take this hormone is as a prescription — but, why?
Investigations1 into OTC products have discovered that melatonin supplements may contain doses that vary anywhere from -83 percent up to +478 percent of what is labeled on the bottle. Even more alarming, some products also tested positive for serotonin, a neurotransmitter and controlled substance used to treat many neurological disorders.
Need help? Check out our guide on top-rated melatonin supplements here.
Even though the synthetic alternative is somewhat similar to the one produced in the body, it doesn’t come without risks. Higher doses could lead to unwanted side effects, especially for those with allergies/sensitivities, people taking medications that have known drug interactions with this hormone, pregnant individuals, and those with prediabetes/diabetes.
To answer the burning question, though, as to whether you can overdose on melatonin, the answer appears to be no.
Research2 in which humans were given varying doses of melatonin in order to determine any toxicity did not find any conclusive evidence that melatonin was lethal.
To sum it up — melatonin is not known to be a potential cause of death, but you should be aware of recommended dosages and possible complications so you avoid taking too much.
Melatonin Dosage
How Much Should You Take?
The majority of studies on melatonin have researched doses ranging from 0.3 milligrams to 10 milligrams as the safest and most effective dose. However, the ideal dose also depends on age, weight, the problem you’re trying to address, along with any current medications that you’re taking. Generally speaking, the ideal dose is the lowest possible dose that provides the desired effects. According to the Cleveland Clinic3, you can start with 1 milligram of melatonin and increase that amount by an additional milligram every week until you get the desired effect.
However, we also advise talking with your doctor first, especially if you take other medications or have certain health conditions.
10mg Dosage
This is the highest dose that is typically used for treating sleep-related conditions and hasn’t been associated with toxicity. 10 milligrams was the dose used in one study4 to handle circadian rhythm disorders in people who are blind. The authors of the study concluded that this dose should always be supervised by a physician.
20mg Dosage
This higher amount should only be used for specific purposes under the supervision of a doctor. For example, some research5 has looked at the use of 20 milligrams of melatonin combined with cancer treatments like radiation and chemotherapy. They found that melatonin could help lower the toxicity of certain substances in chemotherapy. They also found a decrease in adverse effects resulting from this treatment.
30mg Dosage
A 30-milligram dosage is substantial. Some studies6 have used doses of 20-40 mg to prevent and treat clot-forming cells (thrombocytopenia) associated with cancer chemotherapy.
40mg Dosage
As mentioned above, doses in the range of 20-40 milligrams could help with clot-form cells linked to chemotherapy treatments. That being said, this amount is far too high to take on your own, and we would advise against this. If you or someone you know is a cancer patient experiencing clotting issues, you might consider bringing this up with the doctor though.
100mg Dosage
This is a serious dosage, and it shouldn’t be used at all. With this in mind, it’s important to note that this would result in a lot of unwanted effects which could be potentially very harmful.
Melatonin Side Effects
Daytime Sleepiness
Drowsiness is one of the most visible and common side effects of taking too much melatonin, and this is particularly harmful if you take it at the wrong time of the day. For example, it could lead to increased risks when you are operating certain heavy machinery or driving.
Hormonal Changes
When you’re taking a hormone, hormonal changes are bound to happen. However, this could be far more serious than you think. For instance, pregnant women are not advised to take melatonin as not enough research7 has been done to know if it is safe during pregnancy.
Melatonin may also reduce libido in both sexes because it is capable8 of interfering with men’s sperm count and the ovulation cycles of women. With this said, if you are trying to have a baby, you should probably talk to your doctor before taking this supplement.
Some research9 suggests that it could delay puberty and cause other changes in children, so talk to your child’s pediatrician if you have concerns about their sleep.
Headaches
Another possible consequence of taking too much melatonin is a severe headache in the morning. On the one hand, some research10 has found that melatonin supplements may help prevent headaches and migraines. However, keep in mind that this hormone is produced in your brain and as such, taking more than what’s needed could lead to chemical imbalances and quickly spiral into the very thing you’re looking to prevent — headaches.
Dizziness
Dizziness could be another unpleasant side effect of taking too much melatonin. This symptom could also be triggered by an allergic reaction to the supplement. Either way, dizziness is unpleasant and is capable of severely disrupting your ability to function properly.
Paranoia
If you take a higher dose than what’s necessary, you could experience11 delusions, paranoia, confusion, or hallucinations. This hormone is closely tied to other neurotransmitters that regulate mood and behavior, and therefore, higher doses could lead to chemical imbalances and these unpleasant symptoms.
Stomach Issues
This is another common side effect of melatonin, regardless of whether you take it in a regular amount or you overdose it. You may experience stomach issues such as diarrhea, vomiting, and nausea. Any of these symptoms could disrupt your day and make it harder to function normally.
Anxiety & Depression
Anxiety and depression are commonly associated with hormonal imbalances and could be induced12 by taking higher doses of this supplement. If you start experiencing any mental health changes after taking melatonin, speak to your doctor immediately.
Frequently Asked Questions
What is the Lethal Dose of Melatonin?
Every single medicine has its own LD 50. This is the lethal dose when 50 percent of the experimental subjects would die of exposure. Melatonin is known to be relatively safe and an LD50 couldn’t be established13.
How Long Does Melatonin Last?
The plasma half-life is short and ranges between 20 and 50 minutes. This means that approximately only half of the dose remains in your system after this amount of time. This means that while it may help you fall asleep faster, it likely won’t help you to stay asleep or increase the quality of your sleep.
Why Do People Take Melatonin?
Melatonin is the hormone released by our brains to foster sleep, and it is actively used to handle a range of different conditions. As mentioned earlier, melatonin could be useful in various cancer treatments as an additional ingredient to use through chemotherapy, for instance.
Is Melatonin Habit-Forming?
Melatonin is not considered to be habit-forming or cause dependencies, and it is generally safe for short-term use. If you find yourself using it every day for longer than two weeks, it’s important to talk to your doctor about your symptoms to rule out underlying conditions causing problems with your sleep.
Is Melatonin Safe for Kids?
Melatonin has been studied for children with certain conditions, such as autism. There are limited studies about its effectiveness and safety in other children. If you’re considering using melatonin with your child, talk to their pediatrician first.
Can Kids Overdose on Melatonin?
Yes, kids can overdose on melatonin14 just as adults can, and the signs a child has taken too much can include an upset stomach, vomiting, diarrhea, and tiredness. The Centers for Disease Control and Prevention (CDC) reported that from 2012-2021, the number of children ages 5 and up taking melatonin increased by as much as 530 percent15. They go on to say that hospitalizations and more severe symptoms also increased during this time.
What Should You Do if You Consume Too Much?
If you’re worried that you’ve taken too much, call your doctor or a poison control center. While melatonin is considered to be generally safe and has a low toxicity profile, it could cause unpleasant side effects and be dangerous for people with certain conditions or taking other medications.
What Happens If I Take Melatonin With Another Medication?
According to the Mayo Clinic16, taking melatonin should be safe for most people, though in some circumstances it can interact with other medications such as blood thinners, blood pressure medications, anticonvulsants, oral contraceptives, and others. However, this doesn’t mean the interaction will be dangerous, in some cases, it may just inhibit melatonin’s ability to simulate drowsiness.
Before taking melatonin, be sure to discuss your current medications with your doctor to be sure it’s the right choice for you.
Conclusion
Melatonin is a natural hormone that is made in the body, and it’s important for regulating many activities, including sleep. This hormone has many benefits and a high safety profile with few side effects.
That being said, it is possible to take too much melatonin and experience unpleasant symptoms like headaches, drowsiness, an upset stomach, and others. The best way to avoid these is to start with the lowest possible dose and slowly increase until you see the desired effect. As always, before taking any supplement, speak with your doctor.
Sources:
- Erland Lauren A.E., Saxena PhD, Praveen K. “Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content”. Journal of Clinical Sleep Medicine. 2017.
- Malhotra MD, Samir., Sawhney MD, Girish., Pandhi MD, Promila. “The Therapeutic Potential of Melatonin: A Review of the Science”. Webpage accessed October 14, 2023.
- “Melatonin: How Much Should You Take?”. Cleveland Clinic. 2023.
- Sack, RL., Brandes, RW., Kendall, AR., Lewy, AJ. “Entrainment of free-running circadian rhythms by melatonin in blind people”. National Library of Medicine. 2000.
- Rondanelli, Mariangela., Faliva, Milena Anna., Perna, Simone., Antoniello, Neldo. “Update on the role of melatonin in the prevention of cancer tumorigenesis and in the management of cancer correlates, such as sleep-wake and mood disturbances: review and remarks”. Aging Clinical and Experimental Research. 2013.
- Wang, Yi., Wang, Pengcheng., Zheng, Xiaoli., Du, Xing. “Therapeutic strategies of melatonin in cancer patients: a systematic review and meta-analysis”. Onco Targets and Therapy. 2018.
- Voiculescu, S., Zygouropoulos, N., Zahiu, C., Zagrean, A. “Role of melatonin in embryo fetal development”. Journal of Medicine and Life. 2014.
- Lampiao, Fanuel., Du Plessis, Sefan S. “New developments of the effect of melatonin on reproduction”. World Journal of Obstetrics and Gynecology. 2013.
- Holst Andersen, Lars Peter., Gögenur, Ismail., Rosenberg, Jacob., Reiter, Russel J. “The Safety of Melatonin in Humans”. 2016.
- Peres, Mario FP., Masruha, Marcelo R., Zukerman, Eliova., Moreira-Filho, Carlos Alberto., Cavalheiro, Esper A. “Potential therapeutic use of melatonin in migraine and other headache disorders”. Expert Opinion on Investigational Drugs. 2006.
- “Melatonin”. Mental Health America. Webpage accessed October 14, 2023.
- “Complementary & Alternative Medicine for Mental Health”. Mental Health America. Last modified April 8, 2016.
- Guardiola-Lemaître, B. “Toxicology of melatonin”. National Library of Medicine. 1997.
- “Melatonin Overdose in Children”. Cleveland Clinic. 2023.
- Lelak MD, Karima., Vohra, Varun., Neuman MD, Mark I., Toce, MD, Michael S., Sethuraman MD, Usha. “Pediatric Melatonin Ingestions — United States, 2012–2021”. Centers for Disease Control and Prevention. 2023.
- “Melatonin”. Mayo Clinic. Last modified March 3, 2021.
