Melatonin is relatively safe and well-tolerated but adverse effects can occur, especially when there is an overdose.
Melatonin is available as a dietary supplement with a wide range in quality.
It may be given for long periods of time for children with sleep disorders, often in combination with:
(1) neurodevelopmental impairments
(2) autism
(3) ADHD
Adverse effects include:
(1) lethargy
(2) agitation or hyperactivity or mood swings
(3) nightmares
(4) constipation
(5) daytime sleepiness
(6) headache
An overdose may be associated with:
(1) hypotension
(2) increased seizure activity
(3) hypothermia
(4) respiratory failure
Risk factors for overdose:
(1) age less than 2 years of age
(2) excessive melatonin in formulation (more than indicated on label)
(3) accidental ingestion in a toddler playing with medicine bottle, especially gummies
(4) interaction with benzodiazepines
(5) presence of serotonin or other substances in the formulation
(6) misuse of the product
