What are the negative effects of melatonin

Melatonin is a hormone produced in the brain by the pineal gland and plays a role in sleep and circadian rhythm regulation . It is produced as a response of the brain to darkness, for this reason being exposed to light at night can block the production of melatonin.

Melatonin is also available as a supplement and its use is rapidly growing in popularity, usually available as an oral tablet or capsule.

What are the negative effects of melatonin

Scientific research shows that melatonin supplements may help people with insomnia fall asleep a little faster (just 7 or 8 minutes on average) and may have greater benefits for people with delayed sleep phase syndrome (falling asleep very late and waking up late the next day).

Is it safe to take melatonin supplements?

Melatonin taken orally in appropriate amounts is generally safe, but melatonin supplements are not suitable for some people and for those taking some medications.

To make sure melatonin is safe for you, tell your doctor if you:

  • Have you had an allergic reaction to melatonin or any other medication in the past?
  • You have liver or kidney problems
  • You have rheumatoid arthritis, multiple sclerosis or lupus, or any other autoimmune condition

If you are pregnant or breastfeeding a child, it is especially important to consult your doctor before taking any medications or supplements, including melatonin.

Interactions with other medications

Possible drug interactions include:

Anticoagulants and antiplatelet drugs . Combining melatonin with these medications may increase the risk of bleeding.

Nifedipine (Procardia XL). Nifedipine is used to lower blood pressure. Taking melatonin might decrease the blood pressure-lowering effects of nifedipine.


Anticonvulsants . Melatonin may inhibit the effects of anticonvulsants and increase seizure frequency, especially in children with neurological disabilities.

Caffeine . Caffeine can increase or decrease melatonin levels in the body. When taken with melatonin supplements, caffeine appears to increase melatonin levels.

Blood pressure medications . Melatonin may worsen blood pressure in people taking blood pressure medications.

Central nervous system depressants . Using melatonin with these medications may cause a greater sedative effect.

Diabetes medications . Melatonin could affect sugar levels. If you take medications for diabetes, talk to your doctor before using melatonin.

Methamphetamine . Taking melatonin with methamphetamine could increase the effects and side effects of methamphetamine.

Contraceptives. The use of birth control medications with melatonin could cause an additive sedative effect and increase the possible side effects of melatonin.

Cytochrome and Cytochrome Substrates : Use melatonin with caution if you are taking medications such as diazepam and others that are affected by these enzymes.

Fluvoxamine . This medication used to treat obsessive-compulsive disorder can increase melatonin levels, causing unwanted excessive sleepiness.

Immunosuppressants. Melatonin may stimulate immune function and interfere with immunosuppressive therapy.

Medications that reduce the seizure threshold. Taking melatonin with these medications could increase the risk of seizures.

Side effects of melatonin

Some of the mild side effects that have been reported in recent scientific studies include:

  • Headache
  • Dizziness
  • Nausea
  • Drowsiness

Less common side effects of melatonin supplements may include: short-term depression, mild tremors, mild anxiety, abdominal cramps, irritability, decreased alertness, confusion or disorientation.

The possible long-term side effects of melatonin use are unclear.



Experts recommend starting with the smallest dose available (0.5 milligrams to 1 milligram, 30 minutes to an hour before bedtime) and seeing what effect it produces from there. If that has no effect, the dose can be increased gradually.

If melatonin doesn’t help you sleep after a week or two, stop using it and consult your doctor.

Abbas Jahangir

I am a researcher and writer with a background in food and nutritional science. I am the founder of Foodstrend.com, our reputable online platform offering scientifically-backed articles on health, food, nutrition, kitchen tips, recipes, diet, and fitness. With a commitment to providing accurate and reliable information, we strive to empower our readers to make informed decisions about their health and lifestyle choices. Join us on Foodstrend.com's journey toward a healthier and happier lifestyle.

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