Drug Class

  1. Melatonin is a hormone secreted by the pineal gland in the brain.
  2. It helps regulate other hormones and maintains the body’s circadian rhythm.


  • Tablets 10 and 20 mg



  1. Melatonin may help people with disrupted circadian rhythms (such as people with jet lag or those who work the night shift) and those with low melatonin levels (such as some seniors and people with schizophrenia) to sleep better.
  2. Clinical studies suggest that when taken for short periods of time (days to weeks) melatonin is more effective than a placebo in reducing the time it takes to fall asleep, increasing the number of sleeping hours, and boosting daytime alertness.
  3. Some evidence suggests that melatonin may work best for people over 55 who have insomnia.


  1. Melatonin helps control the timing and release of female reproductive hormones. It helps determine when a woman starts to menstruate, the frequency and duration of menstrual cycles, and when a woman stops menstruating (menopause)

Benzodiazepine Withdrawal

  1. Melatonin may help elderly people with insomnia who are tapering off or stopping benzodiazepines

Breast Cancer

  1. Several studies suggest that lower melatonin levels may be associated with breast cancer risk.
  2. Laboratory experiments have found that low levels of melatonin stimulate the growth of certain types of breast cancer cells, while adding melatonin to these cells slows their growth.
  3. Preliminary evidence also suggests that melatonin may strengthen the effects of some chemotherapy drugs used to treat breast cancer.
  4. In a small study of women who were taking tamoxifen for breast cancer but seeing no improvement, adding melatonin caused tumors to modestly shrink in more 28% of the women.

Prostate Cancer

  1. Studies show that people with prostate cancer have lower melatonin levels than men without the disease.
  2. In test tube studies, melatonin blocks the growth of prostate cancer cells.

Irritable Bowel Syndrome:

  1. Some preliminary studies suggest that people with IBS who take melatonin reduce some symptoms of IBS, such as abdominal pain.


  1. Some studies suggest melatonin may reduce the frequency and duration of seizures in children with epilepsy. But other studies suggest melatonin may increase the frequency of seizures. Do not take melatonin for epilepsy or give it to a child without talking to your doctor first.



  1. 1 to 3 mg 1 hour before bedtime
  2. If 3 mg per night does not work after 3 days, try 5 – 6 mg 1 hour before bedtime
  3. The right dose should produce restful sleep with no daytime irritability or fatigue

Jet lag:

  1. 5 – 5 mg of melatonin 1 hour prior to bedtime at final destination has been used in several studies.
  2. Another approach that has been used is 1 – 5 mg 1 hour before bedtime for 2 days prior to departure and for 2 – 3 days upon arrival at final destination.

Drug Interactions

  1. Discuss with you health care provider if you are taking any of the following medications:
  2. Antidepressant medications
    1. Melatonin supplements reduced the antidepressant effects of desipramine and fluoxetine (Prozac) in animal studies
    2. Fluoxetine can cause low levels of melatonin
  3. Benzodiazepines
    1. The combination of melatonin and triazolam (Halcion) may improve sleep quality
    2. melatonin supplements may help patients stop using long-term benzodiazepine therapy
  4. Blood pressure medications
    1. Melatonin may reduce the effects of blood pressure medications like methoxamine (Vasoxyl) and clonidine (Catopres)
    2. Calcium channel blockers may lower melatonin levels.
      1. Nifedipine (Procardia)
      2. Amlodipine (Norvasc)
      3. Verapamil (Calan, Isoptin)
      4. Diltiazem (Cardizem)
      5. Felodipine (Plendil)
      6. Nisoldipine (Sular)
      7. Bepridil (Vascor)
    3. Beta-blockers
      1. Beta-blockers may lower melatonin levels in the body
        1. Acebutolol (Sectral)
        2. Atenolol (Tenormin)
        3. Bisoprolol (Zebeta)
        4. Carteolol (Cartrol)
        5. Metoprolol (Lopressor, Toprol XL)
        6. Nadolol (Corgard)
        7. Propranolol (Inderal)
      2. Anticoagulant:
        1. Melatonin may increase the effect of anticoagulant medications such as warfarin (Coumadin)
      3. Interleukin-2:
        1. In one study of 80 cancer patients, use of melatonin along with interleukin-2 led to more tumor regression and better survival rates than treatment with interleukin-2 alone.
      4. Nonsteroidal anti-inflammatory drugs (NSAIDs)
        1. NSAIDs such as ibuprofen may lower levels of melatonin in the blood.
      5. Steroids and immunosuppressant medications:
        1. Melatonin may cause these medications to lose their effectiveness.
      6. Other
        1. Caffeine, tobacco, and alcohol can all lower levels of melatonin in the body.


  1. Because of the potential for side effects and interactions with medications, people should take dietary supplements only under the supervision of a knowledgeable health care provider.
  2. Some people may have vivid dreams or nightmares when they take melatonin.
  3. Melatonin can cause drowsiness if taken during the day. If you are drowsy the morning after taking melatonin, try taking a lower dose.
  4. Additional side effects include stomach cramps, dizziness, headache, irritability, decreased libido, breast enlargement in men (called gynecomastia), and decreased sperm count.
  5. Pregnant or nursing women should not take melatonin because it could interfere with fertility.
  6. Some studies show that melatonin supplements worsened symptoms of depression. For this reason, people with depression should consult their doctor before using melatonin supplements.


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This document is prepared by the “Mental Health for All” team. This document is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Essentials of Medicine. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.

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