6 Melatonin Side Effects You Should Know About
Key takeaways:
Melatonin is a hormone that regulates your sleep-wake cycle. It’s commonly available as a dietary supplement in the form of pills, gummies, liquids, and more.
Daytime sleepiness is the most common side effect people experience while taking melatonin. Other potential melatonin side effects include sleep changes, headache, and dizziness.
Melatonin side effects are typically mild and temporary. Contact a healthcare professional if your side effects become severe or don’t go away.
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Table of contents
Getting a full night's sleep can be challenging for many people. Life’s stressors, poor sleep habits, and several medical conditions can all contribute to a late night tossing and turning.
If you have trouble sleeping, you’ve likely looked at over-the-counter (OTC) products to help you drift off — such as melatonin. Melatonin itself is a hormone that your brain naturally makes in response to darkness; it tells your body when it’s time to sleep. As a supplement, it can ease sleeplessness related to jet lag, sleep disorders, and anxiety around surgery.
Yet, many people wonder: Is melatonin bad for you? And what are the side effects? Thankfully, melatonin is well tolerated by most people. But, like with any dietary supplement, side effects are possible.
Melatonin side effects at a glance
Melatonin is a natural hormone that your body makes on its own. But taking it as a supplement can have some side effects. Side effects may come from melatonin itself or inactive ingredients that are also found in the product.
Current research suggests that short-term side effects of melatonin are mild. Information on long-term safety is limited, but at this time, there are no reports of any serious, long-term risks in adults. However, if you experience any side effects that feel intense or severe, contact a healthcare professional as soon as possible.
Mild melatonin side effects include:
Headache
Sleepiness
Dizziness
Nausea
Rare but serious melatonin risks include:
Changes to your eyesight, such as blurred vision
Unexplained bruising or bleeding
Feeling depressed or sad
Allergic reactions
Below, we’ll discuss six melatonin adverse effects you may experience while taking this supplement.
Good to know: Side effects are similar between most melatonin dosage forms. This is good news if you’re concerned about side effects from specific formulations, such as melatonin gummies or quick-dissolve tablets. The sleep aid is also available as a pill, liquid, and more.
1. Daytime sleepiness or grogginess
The popular use of melatonin is to make you sleep. However, this sleepiness can carry on into the following day. Daytime sleepiness is when you feel the need to fall asleep despite wanting to be awake. This is the most common side effect people experience while taking melatonin.
Because you still want to sleep, you may feel irritable or agitated. To prevent daytime sleepiness or feeling groggy, make sure you only take melatonin in the evening or in the hours before bed. What’s more, try to avoid taking too much melatonin. This further raises the risk of side effects.
2. Sleep changes
Since you’re supplementing your body’s natural melatonin levels, you may experience changes in your sleeping patterns.
According to the CDC, your brain typically begins producing more melatonin up to 2 hours before your typical bedtime, with peak levels between 2AM and 4AM. By taking additional melatonin at the wrong time, you could shift the timing of your current sleep-wake cycle. This could be helpful if your cycle has been disrupted by travel. But it’s also possible that taking melatonin at the wrong time could cause the supplement not to work.
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3. Headache
Some people experience headaches after taking melatonin. High doses are more likely to trigger these headaches, so try to avoid taking excess melatonin when you can. Sensitivity to melatonin and changes to your sleep cycle can play a role too. Headaches are also a possible symptom of insomnia itself.
Keep in mind that headaches could also be triggered by the inactive ingredients in your melatonin supplement. Be sure to read the medicine label in case you have any sensitivities, such as to color additives.
4. Dizziness
Dizziness is another possible side effect of melatonin. The exact reason why isn’t fully known, but one possibility is related to blood pressure changes. Some studies suggest that melatonin may lower your blood pressure at night.
People who take melatonin, especially those already taking high blood pressure medication, may feel light-headed if their blood pressure gets too low.
5. Upset stomach
You may feel some stomach discomfort after you take melatonin. Melatonin can cause symptoms such as nausea, vomiting, or stomach cramps. Taking too much melatonin can also lead to stomach irritation. Some people may also be more sensitive to oral melatonin regardless of how much they take.
What’s more, some research suggests very low doses of melatonin may lead to diarrhea and higher doses can make you constipated. This is related to how different doses can impact your gut motility.
6. Vivid dreams or nightmares
Studies have shown that taking melatonin can enhance the amount of rapid eye movement (REM) sleep you get at night. This increases the likelihood of experiencing vivid dreams or nightmares. Vivid dreams can be disruptive and can cause you to wake up still feeling tired.
It’s important to note that the severity and frequency of these dreams can vary from person to person. If you’re having vivid dreams frequently as a result of taking melatonin, speak with a healthcare professional. They may suggest you take a lower dosage to see if the vivid dreams calm down.
What can you do to manage melatonin side effects?
Experiencing side effects can be frustrating — especially when they’re from a dietary supplement like melatonin. Thankfully, melatonin’s most common side effects are usually mild and manageable.
Here are some ways to manage melatonin side effects:
Start at a low dose. The chances of experiencing melatonin side effects can depend on the dose you take — so use it with caution. It may be a good idea to start at a low dose of melatonin and then go up if needed. Melatonin supplements are available in doses ranging from 1 mg to 12 mg.
Adjust your dosage, if needed. If you’re experiencing side effects after taking melatonin, consider adjusting your dose. Melatonin doses of 10 mg or higher can cause more side effects. There is no official recommended dosage of melatonin, so finding the right dose for you may take some trial and error.
Try another dosage form. Stomach discomfort is common in the first few days after starting an oral melatonin supplement. But this normally goes away with time, so you may be able to wait it out. You could also try another form of melatonin that’s less likely to cause stomach upset, such as sublingual (under-the-tongue) melatonin.
Turn to other OTC medications, if needed. If you develop a headache while taking melatonin, OTC pain relievers, such as ibuprofen (Advil, Motrin) or acetaminophen (Tylenol), may help. But these products are only meant for occasional use.
If your side effects become severe or don’t go away, contact a healthcare professional for guidance. They may ask you to stop taking melatonin if the side effects are outweighing its potential benefits.
Keep in mind: Melatonin dietary supplements aren’t officially regulated by the FDA for safety and effectiveness. It’s possible for doses to be slightly different than what’s labeled on their packaging. One study found that more than 70% of the time the labeled doses of melatonin products were significantly different than what they actually contained.
Frequently asked questions
No, in fact, it’s possible that melatonin may help with anxiety symptoms. This is likely because sleep problems themselves can contribute to anxiety symptoms. But research on this is relatively limited.
It’s probably safe to take melatonin every night. However, long-term use could mean you have a chronic or unaddressed sleep issue. In this case, it's best to talk to a healthcare professional. They can evaluate your symptoms and help you decide if a different treatment would be more appropriate.
Not necessarily. Melatonin is a hormone that your body naturally makes. While melatonin supplements can have mild side effects and taking too much isn't ideal, they aren’t known to be dangerous or life-threatening when you’re taking a reputable product.
A single dose of melatonin lasts about 5 to 10 hours. But taking extra doses in a short amount of time means your body has to do more work to clear the melatonin. Ultimately, this can make the effects last longer.
The bottom line
Melatonin supplements are generally considered safe to take, and they don’t typically cause many side effects. The most common melatonin side effects are daytime sleepiness and sleep changes. Other side effects include headache, dizziness, and stomach upset. While these side effects are usually mild, you should contact a healthcare professional if they become serious or unmanageable.
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References
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