Melatonin Side Effects

Melatonin helps to control the natural sleep-wake cycle of the human body. The natural levels of melatonin in the blood is highest at the time before bedtime. Melatonin is a hormone which can affect other processes inside the body. Persons at high risk of getting side effects from melatonin are those with liver disease, seizures, depression, kidney disease and high blood pressure. The long term side effects of Melatonin is still unknown. Melatonin’s long term safety has also not been established. There are some concerns about melatonin use being associated with retinal damage.

If you want to take melatonin supplements, melatonin side effects may include:

  • Sleepiness during daytime
  • Feeling Dizzy
  • Headaches
  • Gastric disturbance and abdominal discomfort
  • Confusion
  • Sleepwalking
  • Vivid dreams or Vivid Nightmares
  • Mental or Mood Changes
  • Lowering of body temperature
  • Decreased libido
  • Breast enlargement in men (gynecomastia)
  • Decreased sperm count

Cardiovascular Side Effects of Melatonin

Melatonin may be able to lower blood pressure, this is should be considered for anyone taking medications to control blood pressure. The National Institute of Health also reports that melatonin may increase cholesterol levels. This means that people having high cholesterol levels, atherosclerosis and/or at risk for cardiovascular disease should be careful about taking melatonin supplements.  There are individuals that experienced abnormal heart rhythms when they are are using melatonin. Melatonin supplements may also affect the clotting of blood. People that are taking anticoagulants and/or have blood clotting disorders maybe in danger if they use melatonin supplements.

Side Effects of Melatonin on Blood Sugar

There are type-1 Diabetic patients that developed high blood sugar levels when using melatonin supplements.

Side Effects of Melatonin on Reproductive System and Pregnancy

Decreased sperm count and motility is also reported as one of the side effects of melatonin in men. There are also reports of breast enlargement in men. Melatonin may decrease the fertility in women thus melatonin should not be used by anyone who are planning to become pregnant.  Pregnant women should never take melatonin because of the risk of developmental disorders. Lactating women should not take melatonin because melatonin can be transferred to the baby via breast milk.

Hormonal Side Effects of Melatonin

Hormonal effects are also associated with the use of melatonin supplements. This includes increase or decrease in  thyroid hormone, growth hormone, prolactin, progesterone, estradiol, cortisol and others.

Melatonin can also interact with various drugs, including:

  • Blood-thinning medications or anticoagulants
  • Immunosuppressants
  • Medications used in treating diabetes
  • Birth control medications

Persons who are taking melatonin should be extra careful when doing daytime activities like driving and operating heavy machineries. If taking of melatonin supplement makes you feel drowsy, you should not drive or operate any kind of machinery when you are taking it.

If you want to take melatonin supplements, make sure that you are using the synthetic version and it is not made from animals. Melatonin that comes from animals may contain viruses and other contaminants which could be dangerous to your health.

Make sure that you stick with the recommended dosage for melatonin and always consult a doctor before taking melatonin supplements. Melatonin when used on children will also have similar side effects.

Reference: Randomized, double-blind clinical trial, controlled with placebo, of the toxicology of chronic melatonin treatment

J Pineal Res. 2000 Nov;29(4):193-200. Seabra ML, Bignotto M, Pinto LR Jr, Tufik S. Department of Psychobiology, Universidade Federal de São Paulo, Brazil

– The objective of the present study was to assess the toxicology of melatonin (10 mg), administered for 28 days to 40 volunteers randomly assigned to groups receiving either melatonin (N = 30) or placebo (N = 10) in a double-blind fashion. The following measurements were performed: polysomnography (PSG), laboratory examinations, including complete blood count, urinalysis, sodium, potassium and calcium levels, total protein levels, albumin, blood glucose, triglycerides, total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very low-density lipoprotein (VLDL), urea, creatinine, uric acid, glutamic-oxalacetic transaminase (GOT), glutamic-pyruvate transaminase (GPT), bilirubin, alkaline phosphatase, gama-glutamic transaminase (GGT), T3, T4, TSH, LH/FSH, cortisol, and melatonin serum concentrations.

– In the present study we did not observe, according to the parameters analyzed, any toxicological effect that might compromise the use of melatonin at a dose of 10 mg for the period of time utilized in this study.

Melatonin References:

Piccirillo JF. Melatonin. Prog Brain Res . 2007;166:331-3.

Pillar G, Shahar E, Peled N, Ravid S, Lavie P, Etzioni A. Melatonin improves sleep-wake patterns in psychomotor retarded children. Pediatr Neurol . 2000;23(3):225-228.

Ram PT, Yuan L, Dai J, Kiefer T, Klotz DM, Spriggs LL, et al. Differential responsiveness of MCF-7 human breast cancer cell line stocks to the pineal hormone, melatonin. J Pineal Res . 2000;28(4):210-218.

Reiter RJ. Melatonin: clinical relevance . Best Pract Res Clin Endocrinol Metab . 2003;17(2):273-85.

Sack RL, Brandes RW, Kendall AR, Lewy AJ. Entrainment of free-running circadian rhythms by melatonin in blind people. N Engl J Med . 2000;343(15):1070-1077.

Schernhammer E, Hankinson S. Urinary melatonin levels and breast cancer risk. J Nat Canc Instit 2005;97(14):1084-1087.

Shamir E, Barak Y, Shalman I, Laudon M, Zisapel N, Tarrasch R, et al. Melatonin treatment for tardive dyskinesia: a double-blind, placebo-controlled, crossover study. Arch Gen Psych . 2001;58(11):1049-1052.

Shamir E, Laudon M, Barak Y, Anis Y, Rotenberg V, Elizur A, et al. Melatonin improves sleep quality of patients with chronic schizophrenia. J Clin Psychiatry . 2000;61(5):373-377.

Simko F, Pechanova O. Potential roles of melatonin and chronotherapy among the new trends in hypertension treatment. J Pineal Res. 2009 Sep;47(2):127-33. Epub 2009 Jun 29. Review.

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