Is It Safe to Take Melatonin?

Reviewed on 9/22/2020

What Is Melatonin?

Melatonin is one of the hormones that govern sleep. Melatonin supplements can treat insomnia and jet lag, and are generally safe in over-the-counter doses.
Melatonin is one of the hormones that govern sleep. Melatonin supplements can treat insomnia and jet lag, and are generally safe in over-the-counter doses.

Melatonin is a hormone produced in the pineal gland, a pea-sized gland located in the brain. Melatonin helps send signals to distant organs and plays a role in sleep and circadian rhythms.

The body naturally produces more melatonin at night which helps people fall asleep, and levels are lower in the morning when people awaken and are exposed to light. Melatonin levels decline as people age. 

What Is Melatonin Used For?

Melatonin is available as an over-the-counter (OTC) supplement used for:

Low doses (0.1 to 0.5 mg) are recommended for insomnia or jet lag because high doses can alter normal day/night melatonin rhythms.

The use of melatonin to treat other conditions is being investigated. 

  • Cancer
    • Melatonin is being investigated for slowing tumor progression
    • In one study, patients with untreatable metastatic solid tumors treated with melatonin experienced less weight loss that those treated with supportive care alone, despite similar caloric intake
    • Melatonin in combination with aloe vera may have immunomodulating properties
  • Alzheimer's disease
    • Melatonin secretion is inhibited in Alzheimer’s patients and one study reported AD patients treated with melatonin showed a decrease in sundowning (changes in behavior in the afternoon and evening)
    • Another study showed improved sleep quality 
  • Amyotrophic lateral sclerosis (ALS, also called Lou Gehrig’s disease)
    • Melatonin is being investigated as a neuroprotective compound and antioxidant in patients with sporadic ALS
  • High nighttime blood pressure
    • One study showed melatonin treatment reduced nighttime blood pressure 
  • Sleep problems in children with autism spectrum disorders (ASD)
    • Children with ASD may have lower levels of melatonin, and some research has shown supplemental melatonin to be effective and relatively safe in treating sleep problems in ASD children and adolescents

What Are the Side Effects of Melatonin?

Side effects of over-the-counter melatonin supplements include:

Side effects of ramelteon (Rozerem), a prescription melatonin agonist include:

What Are Risks of Melatonin Use?

While melatonin is generally safe for use at lower doses, always consult your doctor before taking any supplement. Possible risks of melatonin use include:

  • Drug interactions
  • Allergic reaction
  • Unknown if it is safe for use during pregnancy or while breastfeeding 
  • American Academy of Sleep Medicine recommends against melatonin use by people with dementia
  • May cause daytime drowsiness, especially in older people 
  • Because it’s classified as a dietary supplement in the U.S. and not a drug, it is less strictly regulated by the Food and Drug Administration (FDA) 
    • Melatonin products may not contain what’s listed on the label
      • One study found most supplements did not contain the amount of melatonin that was listed on the package 
      • About one-quarter of the supplements contained serotonin, a hormone that can have harmful effects even at low levels

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Reviewed on 9/22/2020
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