Melatonin Safety: 10 Things You May Not Know About This Popular Sleep Aid

Image of melatonin pills on a blue background
Eleonora Grigorjeva/Getty Images/iStockphoto

The most important things to know before taking melatonin:

  • It can cause side effects such as headaches, dizziness, or nausea if taken at too high a dose.  
  • It is not recommended if you are pregnant or breastfeeding. 
  • It is not recommended if you have an autoimmune disease. 
  • It is not recommended for older adults with dementia. 
  • It can cause harmful interactions with certain prescription drugs, including blood thinners and blood pressure medicines. 

Recently you’ve joined the ranks of the 50-to-70 million Americans who struggle to wind down once their head hits the pillow. You need a sleep aid, at least temporarily, but you’re wary of pharmaceuticals. So you pick up a bottle of melatonin, the popular so-called natural supplement everyone seems to be either talking about or taking.

And you can buy it over the counter, so it must be safer than prescription meds. Right?

“Not so fast,” says Michael J. Breus, Ph.D., clinical psychologist and a fellow of the American Academy of Sleep Medicine. He and other experts agree: Melatonin isn’t a totally risk-free, one-size-fits-all cure for sleep problems. “Melatonin isn’t a panacea, nor is it suitable for everyone,” he says.

For starters, although melatonin isn’t a prescription drug, it nevertheless has contraindications — meaning that it shouldn’t be used in some situations or by people with certain health conditions.

For those with no contraindications, melatonin is likely not harmful, according to Luis F. Buenaver, Ph.D., director of the Behavioral Sleep Medicine Program at Johns Hopkins Medicine. But for melatonin to be safe and effective, it still needs to be taken at the right dose, in the right way, at the right time.

When you shouldn’t take melatonin

Girl pouring two tablets of melatonin into her hand
LP/Getty Images/iStockphoto

In some cases, melatonin is not recommended. In others, it should be used only on the advice of your doctor. To be on the safe side, get an OK from your physician before adding it to your supplement routine.

1. Can you take melatonin if you are taking other prescription drugs?

If you’re on prescription drugs, always talk to your doctor before starting a melatonin supplement, Breus emphasizes. This is especially critical if you’re using any of these prescription medications:

  • anti-seizure drugs: melatonin can reduce the effectiveness of anticonvulsants and interfere with medications for epilepsy 
  • blood pressure medications: melatonin can increase blood pressure in people taking drugs for hypertension 
  • blood thinners: when taken with anticoagulants and antiplatelet drugs, melatonin may increase the risk of bleeding 
  • diabetes medications: melatonin can raise blood glucose levels in diabetics 
  • immunosuppressants: melatonin can interfere with immunosuppressive therapy 
  • medication to treat obsessive-compulsive disorder: melatonin can magnify the sedative effect of central nervous system depressants 

2. Which health conditions may not benefit from melatonin?

Melatonin is also not recommended if you have an autoimmune disease or are an older adult with dementia. In some studies, melatonin has shown a tendency to stimulate inflammation in people with certain autoimmune disorders. Research looking at the efficacy of melatonin for insomnia in older adults with dementia found marginal benefits, citing supplement-free and medication-free alternatives to be less risk.

Working on sleep hygiene and incorporating meditation or body relaxation techniques, like progressive muscle relaxation, is shown to improve insomnia.

3. Can you take melatonin while pregnant?

Insomnia during pregnancy is shown to increase towards the third trimester. Still, experts stress caution when considering melatonin for pregnancy sleeplessness.

“Unfortunately, when it comes to melatonin and pregnancy, there’s currently not enough research to confirm that taking melatonin while pregnant or breastfeeding is safe,” says Breus.

Because melatonin levels naturally rise throughout pregnancy, one potential risk of supplementing is giving your body too much melatonin. Melatonin is thought to help determine an unborn baby’s circadian rhythm, and an imbalance could potentially impact a child’s sleeping patterns after birth.

4. Does melatonin affect birth control?

There’s also not much research on how melatonin supplements and oral contraceptives interact, and existing studies have yielded inconsistent results.

“It’s best to be cautious,” says Breus. “If you’re using oral contraceptives and are interested in trying melatonin, check with your doctor first. He or she might recommend trying other sleep-promoting methods to start.”

5. Does melatonin interact with alcohol?

Research has long established alcohol’s penchant for interfering with many medications and supplements. However, there’s not much research into its effects on melatonin. Most experts agree that you should avoid drinking alcohol while taking melatonin, as the potential risks and side effects aren’t fully understood.

Other must-know facts about melatonin safety

If you’ve assessed those essential precautions and are still considering melatonin, use these facts to navigate safe dosing, timing, and more.

Infographic describing suggestions for melatonin dosage and timing. Best time: About 30-60 minutes before bed. Time release melatonin for difficulty staying asleep, and always starting at the lowest dosage possible. Talk to your doctor before trying supplements.
Ashlee Wadeson

Melatonin doesn’t work like a sleeping pill

Melatonin is a hormone your body produces that’s triggered by darkness. When receptors in our retinas detect a lack of light, a signal is sent to activate the pineal gland, a pea-shaped gland in the brain, and melatonin is released into the body. This brings on physiological changes like decreased body temperature and respiration rate, as well as drowsiness.

This is an important distinction: Melatonin doesn’t knock you out like a sleeping pill. Rather, it causes physiological changes that put your body in a quieter state, which promotes sleep.

You shouldn’t take melatonin during the day

If you’re considering melatonin to help you sleep, you don’t want to take it during the day. “It will basically tell your brain that it’s bedtime, and you’ll feel it,” says Breus.

When should you take melatonin? About a half-hour to an hour before bed. Breus advises choosing a timed-release supplement so your melatonin level won’t peak and then drop off too soon. By doing so, you can align your supplement with your body’s natural melatonin secretion, which increases soon after it gets dark out, peaks between 2 a.m. and 4 a.m., and then gradually falls during the second half of the night.

With melatonin, less is more

How much melatonin should you take? Though there’s no official recommended dosage for adults, a range of about .05 mg to 5 mg has been shown to be safe and effective. “Your melatonin dosage depends on why you’re taking it,” says Breus. “For most people, I recommend 0.3 mg to 5 mg, at least to start, and see how your body responds.” 

Starting at a lower dose can help prevent melatonin side effects, which may include mild headaches, dizziness, nausea, and drowsiness. (Other less common side effects may include mild anxiety, stomach cramps, disorientation, and short-term depression, Breus notes.)

Infographic listing the side-effects of melatonin: headaches, nausea, dizziness, drowsiness
Ashlee Wadeson

How much melatonin is too much? Although you might find melatonin supplements in doses up to 10 mg, this is much more than your body needs, according to experts.

You may also want to talk to your doctor about magnesium supplement. “Magnesium is important because it helps regulate the body’s melatonin production, with lower levels of magnesium usually linked to lower melatonin levels,” Breus says.

Melatonin isn’t meant for long-term use

Melatonin hasn’t been studied for long-term use or safety. And although melatonin is not addictive like some prescription sleep aids, experts say that it’s not meant to be used as a long-term solution to sleep problems.

If you aren’t seeing results after a week or two, stop using melatonin and talk to your health care provider, Buenaver recommends. People who find melatonin helpful can take it nightly for a month or two, then stop and assess their sleep quality. That’s usually all it takes to get your body back on a normal sleep cycle, he says.

Melatonin isn’t regulated by the FDA

The U.S. Food and Drug Administration (FDA) doesn’t regulate melatonin — or any other dietary supplement, for that matter. This means these products aren’t tested for safety, potency, or effectiveness and could also contain harmful ingredients.

“The reliability of melatonin supplements varies widely,” says Breus. “One study found an incredibly wide range in how much melatonin supplements contained: Some had 83% less than marketed, while others had nearly 500% more. That’s a problem, of course, because you can easily end up taking an improper dose through no fault of your own.” 

The same study also found serotonin, a much more strictly-controlled substance, in 26% of the tested supplements. This could lead to serious side effects for people taking selective serotonin reuptake inhibitors (SSRIs), which are antidepressants that increase serotonin levels in the brain.

When choosing a supplement, “do your research,” Breus says. “I can’t stress this enough. Ask your doctor or pharmacist for a recommendation.”

While not official, third-party certifications from organizations like U.S. Pharmacopeia (USP) or the National Sanitation Foundation (NSF) offer some assurance about the accuracy of an ingredient list. EcoWatch, an environmental watchdog, put out a list this year of six recommended melatonin supplements it recommends, along with information about the selection process.

How to boost your body’s melatonin naturally

Infographic showing how natural melatonin rises at night and goes down in the morning, in accordance with light exposure
Ashlee Wadeson

With the right lifestyle tips and schedule, you may be able to manage melatonin production naturally. Incorporate these simple, natural strategies into your daily wellness routine. Then, consider using a sleep tracker or sleep diary to evaluate their impact on your sleep quality.

  • Get plenty of sun at the right time. Sunlight aids in the body’s production of serotonin, the precursor to melatonin. When we’re exposed to sunlight, especially in the morning, our nighttime melatonin production happens earlier in the evening. That helps us transition into sleep more easily. 
  • Lower the lights an hour before bedtime. When you’re ready to go to sleep, make your bedroom as dark as possible. This encourages melatonin release and helps promote relaxation as your body and mind prepare to sleep. 
  • Get moving. Moderate aerobic exercise may increase the production of nighttime melatonin. Logging 30 minutes of activity during the day can burn off energy, calm anxiety, and boost your mood — and should also help you sleep better that same night
  • Eat melatonin-boosting foods. Some foods contain enough melatonin to possibly make a difference in your sleep cycle. Almonds and walnutseggs, and fatty fish like wild salmon can help, as can lettuce, kiwifruit, cherries, and chamomile tea. Warm milk, a tried-and-true home remedy for sleeplessness, contains four sleep-promoting compounds: tryptophan, calcium, vitamin D, and melatonin. 
  • Meditate. Meditating in the evening can encourage relaxation and lower nervous system arousal, which encourages melatonin release.