Is Long-term Use of Melatonin Safe?

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Is Long-term Use of Melatonin Safe?

Written by Tegan Smedley, PharmD, BCPS, APh | Reviewed by Aunna Pourang, MD Published on December 22, 2021print_outlinedemail_outlined

Key takeaways:

  • Melatonin is a dietary supplement. Dietary supplements don’t need to perform the same safety and effectiveness studies as prescription medications before being sold. 
  • Short-term melatonin use appears to be safe for most adults and has mild side effects at low doses.
  • There’s not enough information available to fully judge the safety of long-term melatonin use. But so far, studies suggest that long-term side effects are generally mild.
Black and white photo of a melatonin bottle with pills laid out on a plain background. There is also a silk eye mask in the top corner of the frame.

Up to 50% of U.S. adults have trouble sleeping from time to time. For 1 in 3 people, insomnia (trouble sleeping) is a long-term problem. According to the Centers for Disease Control and Prevention (CDC), adolescents are even more sleep-deprived. In 2015, it was estimated that 6 out of 10 middle schoolers and 7 out of 10 high schoolers got less than the recommended amount of sleep.

So it’s no wonder that many people reach for an over-the-counter (OTC) product to help them sleep. A popular choice is melatonin, an OTC dietary supplement used to promote healthy sleep patterns. In fact, it’s so popular that people in the U.S. spent about $378 million in 2014 just on melatonin supplements. But how safe is it to take melatonin on a daily basis?

Below, we’ll discuss what we know about the short- and long-term effects of taking melatonin supplements.

What is melatonin? 

Melatonin is a hormone, or chemical messenger, that your brain naturally makes when it becomes dark at night. It sends the message to the rest of your body that it’s bedtime and helps regulate your sleep cycle. Melatonin is also made synthetically in a lab and can be taken by mouth as an OTC dietary supplement. 

People commonly take melatonin supplements for jet lag, sleep disorders, and anxiety before or after surgical procedures. But many health experts, including the American Academy of Sleep Medicine (AASM), don’t recommend using it for insomnia due to a lack of supporting evidence for its use.

Things to consider before taking melatonin

Be sure to check with your healthcare provider or pharmacist before taking any dietary supplement, including melatonin. Even though melatonin is a natural product, that doesn’t mean it’s safer for you than other OTC sleep aids, like Unisom (doxylamine). There may still be interactions with medications, health conditions, or food items, like alcohol. 

The difficulty with dietary supplements

The FDA hasn’t approved melatonin for use with any medical condition. And since melatonin is a dietary supplement, it’s not regulated as rigorously as prescription medications are by the FDA. This means that companies that sell melatonin aren’t required to undergo the same research to demonstrate how safe and effective their product is before it’s sold on the market. 

Unfortunately, less regulation could also mean that your melatonin product may not be as strong as or be stronger than the bottle claims. One study found that over 70% of melatonin supplements contained a significantly different amount of melatonin than what was listed on the bottle. For example, one product had almost five times more melatonin in each dose than what the bottle claimed.

If you’re interested in taking melatonin, talk with your healthcare provider and pharmacist about how to safely choose OTC dietary supplements.

How much melatonin is safe to take?

Melatonin supplements come in a range of strengths, most commonly from 1 mg to 12 mg. A common dose for adults trying melatonin for the first time is 3 mg. A review of multiple studies reported no side effects at this dose. But short-term side effects are possible with melatonin. 

Melatonin side effects are typically mild and may include:

  • Drowsiness 
  • Headache
  • Nausea
  • Dizziness

Is short-term melatonin use safe?

Current research suggests short-term melatonin use should be safe for most people. Unfortunately, there’s not enough research to define what lengths of time are considered short term and long term. If your sleep problems last for more than a few weeks, it’s time to check in with your healthcare provider. This is to make sure there isn’t another medical condition causing your insomnia and to get you the best treatment. 

Is long-term melatonin use safe?

There aren’t enough studies to say whether long-term melatonin use in adults or children is safe. A few clinical trials suggest that long-term melatonin use may cause mild side effects compared to placebo (a pill with no medication in it). But more research is needed to confirm the long-term safety of melatonin supplements.

Can you take melatonin every night?

Some people do, but it’s best to ask your healthcare provider if this is OK for you. Melatonin can also be taken just when needed. With any sleep aid, it’s best to use the lowest dose that’s effective for you. And unless directed by a healthcare provider, you should stop taking sleep aids if your sleep problems resolve. 

The good news is that studies suggest people don’t become addicted to melatonin, even with continuous use. So melatonin could be a possible option if you’re concerned about the habit-forming nature of some prescription sleep medications. However, some people find that melatonin stops working for them after they take it for a while.

Does long-term melatonin use lead to health risks?

The health risks of long-term melatonin use are still unknown due to a lack of high quality studies. But from what has been studied so far, melatonin doesn’t seem to cause any serious problems.

Some experts have raised concerns about whether melatonin supplements could negatively affect puberty and male reproductive health. More research is needed to determine if either concern is an issue.

There’s also not enough research to determine if melatonin is safe during pregnancy or while nursing. Pregnant or nursing women should speak with their healthcare provider before taking melatonin.

Is melatonin safe for kids?

Possibly, but experts are still unclear. Based on the research currently available, short-term melatonin use seems to be safe for most children. But clinical studies about melatonin in kids are limited. Because of this, there are no clear recommendations on how much melatonin to give children, for how long, or if it’s safe long term.

Some studies suggest low doses may help children sleep. But the dose should be individualized for your child by a healthcare provider. Talk to your child’s healthcare provider before giving melatonin supplements to your children or teens.

The bottom line

Melatonin is a popular OTC sleep aid. However, there’s limited information available about its long-term safety. There are even fewer studies on whether melatonin is effective or safe for children. Because of this it’s best to speak with a healthcare provider before taking melatonin. If you’re already taking melatonin and still not getting good quality sleep, speak to your provider to discuss other options.

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