When you’re struggling with chronically poor sleep, taking a melatonin supplement can, in some cases, offer much-needed relief. However, if you've ever wondered what happens if you take too much melatonin, experts say that it can backfire, causing a range of side effects and even interrupting your natural circadian rhythm, resulting in worse sleep in the long-term.
HaVy Ngo-Hamilton, PharmD, a BuzzRx Clinical Consultant, notes that the U.S. Food & Drug Administration (FDA) does not regulate dietary supplements like melatonin nor does it provide dosage recommendations. However, Ngo-Hamilton says that the usual safe and effective dose range is 0.5 mg to 5 mg at bedtime. She says taking eight to 10 milligrams for up to six months can be helpful for some people with severe sleep issues, but does not recommend taking more than 10 milligrams daily.
“You should always take the lowest dose of melatonin that helps you sleep,” she tells Best Life.
The Mayo Clinic adds that melatonin should never be used as the "first or only remedy" for poor sleep: "It needs to be coupled with lifestyle choices that create a solid foundation for good health." Things like following a healthy diet and exercise routine, practicing good sleep hygiene habits, cutting out or cutting back on nicotine, caffeine, and alcohol, and managing your stress can all lead to significant improvements in sleep duration and quality.
If after that you still decide to take melatonin as a sleep aid, it’s important to do so safely, with the possible adverse effects in mind. Read on to learn what happens when you take too much melatonin, according to doctors.
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1. You may experience nausea, vomiting, or other gastrointestinal symptoms.
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When you take too much melatonin, your body will attempt to get rid of excessive amounts of the substance. In extreme cases, you may actually vomit, says Ngo-Hamilton, explaining that vomiting is your body’s emergency response to poisoning.
Even if you don’t actually vomit, you may feel nauseous after taking too much of the sleep aid.
According to the Mayo Clinic, stomach cramps, diarrhea or constipation are also considered common side effects.
2. You may experience blood pressure changes.
iStockIn some cases, too much melatonin can raise your blood pressure, says Ngo-Hamilton. This is especially true if you take blood pressure medication, the Mayo Clinic advises.
Because even safe doses of melatonin can cause dangerous spikes in blood pressure, their experts don't recommend taking it at all if you’re already on medication for hypertension. Needless to say, it’s even riskier to take high doses of melatonin if you have this condition.
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3. You might develop a headache.
ShutterstockPaul Peak, PharmD, VP of Clinical Pharmacy at Sedgwick, says it’s also common to get a headache after taking an excessive amount of melatonin. You can take an over-the-counter pain reliever to help alleviate this symptom.
If you think you’ve taken a little too much melatonin, Ngo-Hamilton says the best thing to do is wait for it to leave your system, which usually takes about five hours. However, if you start experiencing vomiting, trouble breathing, or excessive sleepiness that won’t subside, it’s best to contact poison control or call 911.
4. You might feel sleepy, groggy, or dizzy the next day.
ShutterstockWhile the right amount of melatonin may help you wake up feeling rested, taking too much may actually have the opposite effect.
According to Ngo-Hamilton, excessive amounts of melatonin can disrupt your circadian rhythms, potentially leading to poorer quality sleep in the long-term. That’ll leave you feeling extra groggy for the first few hours after you wake up. You may feel low in energy, need to press the snooze button a few times, or find it difficult to get out of bed.
However, Ngo-Hamilton notes that melatonin clears out of the body pretty quickly, so these symptoms shouldn’t last all day long. As long as you take a moderate dose of melatonin about 30 minutes to an hour before bedtime, and do not have to wake up in less than five hours, you probably won't have grogginess as a side effect, she says.
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5. It may interact with your other medications.
iStockIf you take melatonin every night as a sleep aid, you may also increase your risk of the supplement interacting with your other medications.
The Mayo Clinic notes that certain medication types are more likely than others to cause interactions. These include medicines that slow blood clotting, prevent seizures, manage blood pressure, manage diabetes, or suppress the immune system.
Their experts add that any medicine that is broken down by the liver has the potential to interact with melatonin. Speak with your doctor or pharmacist to find out if your medications are safe to take with short-term doses of melatonin.
6. It could interfere with your natural hormone production.
ShutterstockScientists are still working to understand the ways that taking melatonin regularly could impact your normal hormone production—especially in younger users.
"Because melatonin is a hormone, it's possible that melatonin supplements could affect hormonal development, including puberty, menstrual cycles, and overproduction of the hormone prolactin, but we don't know for sure," says the National Center for Complementary and Integrative Health (NCCIH), a branch of the National Institutes of Health (NIH).
If you think you’ve taken a little too much melatonin, Ngo-Hamilton says the best thing to do is just wait for it to leave your system, which usually takes about five hours. However, if you start experiencing vomiting, trouble breathing, or excessive sleepiness that won’t subside, it’s best to contact poison control or call 911.
