MSD Manual

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Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Reviewed/Revised Jan 2022 | Modified Sep 2022

What is melatonin?

What claims are made about melatonin?

People use melatonin mostly to treat insomnia Insomnia and Excessive Daytime Sleepiness (EDS) The most commonly reported sleep-related problems are insomnia and excessive daytime sleepiness. Insomnia is difficulty falling asleep or staying asleep, waking up early, or a disturbance in... read more and to help minimize the effects of jet lag Circadian Rhythm Sleep Disorders Circadian rhythm sleep disorders occur when people’s internal sleep-wake schedule (clock) does not align with the earth’s cycle of darkness (night) and light (day). Jet lag and shift work commonly... read more or of shift work. People who are traveling across time zones may take melatonin on the day or night of departure and for 2 to 4 nights after arrival. People who rotate work shifts may take melatonin before going to bed. Research is being conducted in using melatonin to resynchronize the sleep-wake cycle for people in the early phases of Alzheimer disease, as well as for seasonal affective disorder (feeling depressed during winter months).

Does melatonin work?

Evidence suggests that melatonin supplements can affect the sleep-wake cycle. Thus, melatonin supplements may help certain people with symptoms of jet lag or temporary insomnia and has been used for as long as 6 months. However, there is little evidence that melatonin effectively treats chronic insomnia.

What are the possible side effects of melatonin?

Headache and transient depression may occur. Melatonin may increase existing depression. Whether melatonin is safe when used long-term is unknown. Melatonin is best taken under medical supervision. If animal sources are used, infections may occur, caused by animal tissue contamination. In people with epilepsy Seizure Disorders In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction. Many people have unusual sensations just before a seizure... read more , melatonin may increase seizures. Melatonin may exacerbate autoimmune diseases Autoimmune Disorders An autoimmune disorder is a malfunction of the body's immune system that causes the body to attack its own tissues. What triggers an autoimmune disorder is not known. Symptoms vary depending... read more . Also, melatonin may decrease fertility, and whether melatonin is safe in pregnancy or while breastfeeding is unknown.

What drug interactions occur with melatonin?

Melatonin may increase effects of warfarin, increasing risk of bleeding. Melatonin may enhance the sedative effects of certain drugs such as benzodiazepines. Some drugs may affect melatonin levels. For example, fluvoxamine, estrogens, and quinolone antibiotics may increase melatonin levels. Conversely, some drugs (for example, the antiseizure drug carbamazepine and the antibiotic rifampin) may decrease melatonin levels.


People with problems sleeping or who want to treat or prevent jet lag can try melatonin, but most, particularly those considering taking melatonin repeatedly, should consult with their doctor first. Melatonin should not be taken by people with epilepsy or autoimmune diseases, women trying to become pregnant, or those taking warfarin.

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