The side effects of melatonin are infrequent and typically minimal, based on available anecdotal and clinical evidence. There are many important questions that still need to be answered regarding the safety, benefits, and risks of melatonin use. Is melatonin bad for you, especially when it’s taken for a long period? Can too much melatonin hurt you? How much melatonin is too much? Can taking melatonin every night be bad? Does melatonin offer other health benefits?
Information from early studies is still insufficient, but initial findings do indicate that melatonin is generally safe for short-term use. But as with any supplement or medication, you must be fully aware of the potential melatonin side effects.
Article at a Glance
- Available evidence indicates that short-term melatonin use may only produce mild and temporary side effects.
- The health effects of long-term melatonin use is still unknown and caution must be taken when using melatonin for a prolonged period.
- Proper dosage can help minimize side effects and ensure the effectiveness of melatonin.
Does Melatonin Have Any Side Effects?
Melatonin is typically recommended to provide relief from circadian rhythm sleeping disorders, such as jet lag, delayed sleep-wake cycles, irregular sleep-wake cycles, and shift work disorder; it may also be prescribed by doctors to help children with developmental disorders, such as autism spectrum disorder or ADHD, enjoy normalized sleep patterns and improved sleep quality.
The many unknowns about the potential long-term side effects of melatonin are, of course, more concerning when the supplement is given to children. Short-term melatonin use appears to be generally safe for most children; however, this finding is based on meager research involving children. Given that melatonin is a hormone, the foremost concern of scientists is how melatonin might impact the hormonal development of children and adolescents.
Below are common melatonin side effects in children. Based on reports, these side effects are usually mild.
- Drowsiness
- More frequent urination at night
- Increased bedwetting
- Dizziness
- Headache
- Agitation
Among adults, the known side effects of short-term melatonin use include:
- Sleepiness
- Dizziness
- Nausea
- Headache
It’s important to note that the desired effect of melatonin — inducing sleep/sleepiness — may also become an unwanted side effect when it occurs during the daytime, usually as a result of too much or improper timing of melatonin intake.
Other Concerns
There isn’t a lot of information about the overall safety of melatonin, but short-term use following recommended dosages appear to offer benefits that outweigh any potential mild and temporary side effects. However, experts recommend taking extra precaution concerning the following.
- Melatonin may interact with certain medications. Always consult your doctor before using melatonin if you’re already taking other medications. If you have epilepsy or are taking blood thinners, melatonin use should only be done under a doctor’s supervision.
- Melatonin should not be taken with fluvoxamine, ramelteon, or tasimelteon.
Melatonin may adversely interact with:
- alcohol
- caffeine
- carbamazepine
- certain antibiotics like ciprofloxacin
- certain medicines for depression, anxiety, or psychotic disturbances
- cimetidine
- female hormones, like estrogens and birth control pills, patches, rings, or injections
- methoxsalen
- nifedipine
- other medications for sleep
- other herbal or dietary supplements
- phenobarbital
- rifampin
- smoking tobacco
- tamoxifen
- Melatonin may cause an allergic reaction in some individuals. Although rare, allergic reactions may include skin rash, itching or hives, or swelling of the face, lips, or tongue.
- Melatonin may not be safe for pregnant and breastfeeding women. Melatonin is transferred into breast milk and can cause excessive sleepiness in nursing infants.
- Melatonin may not be safe for people with dementia.
- Melatonin may have a prolonged effect on older people and pose an increased risk for daytime drowsiness.
- Melatonin, like other dietary supplements, are not strictly regulated by the FDA, so quality control for safety and effectiveness is not guaranteed.
- Some brands may not contain what’s indicated on their label. The ingredients list may not be accurate, particularly the actual melatonin content.
What’s the Right Dosage?
The correct melatonin dosage is not only key to getting the desired effect, but also to minimizing the potential side effects of melatonin. The appropriate dosage is typically based on an individual’s body weight; but keep in mind that every individual also metabolizes melatonin at different rates.
There is no established optimal dose for melatonin, but general dosage recommendations range from 1 mg to 5 mg. Experts advise starting with the lowest dose possible, and then slowly increasing intake until you determine the best dose that helps you fall asleep without causing any unwanted side effects. Currently, data regarding melatonin effects on dreams, melatonin effects on weight gain, and melatonin and disrupted circadian rhythms are largely conflicting and insufficient.
If you’re not sure about how much melatonin you should take, always consult your doctor.
Most melatonin tablets are immediate-release melatonin, which means the melatonin is immediately released into the bloodstream so the effect happens right away. You can take this supplement a few minutes or up to 30 minutes before bedtime.
Other melatonin products, such as melatonin gummies, are extended-release or slow-release melatonin. The release of melatonin into the bloodstream is delayed; it may take 1 to 2 hours before you experience its effects. You can take this kind of supplement 1 to 2 hours before bedtime.
Melatonin generally stays in the body for about 5 hours, before it is completely cleared from the body. Driving, using heavy machinery, and other similar activities should be avoided within 5 hours of taking melatonin. But the clearance time of melatonin may differ for every individual depending on the following factors:
- Age
- Overall health condition
- Body composition
- Whether the melatonin is extended-release or immediate-release
- Frequency of melatonin use
- Caffeine intake
- Tobacco use
- Other medications
Final Thoughts
Remember that as a dietary supplement, melatonin is not strictly regulated by the FDA. What is known regarding the side effects of melatonin, particularly when used over a long period, is still preliminary and inconclusive. Short-term melatonin use is generally safe for most individuals, but making sure that you choose a good quality product is important to ensure quality, safety, and effectiveness.
The side effects of melatonin may also depend on dosage. Whenever possible, consult your doctor to determine the appropriate dosage for your age and body weight; otherwise, carefully follow the dosage recommendations printed on the product label. And it’s highly recommended to start with the lowest recommended dose so you can better gauge how your body responds to the supplement.
