In an umbrella review of melatonin supplementation, reported adverse effects appeared uncommon, and were predominantly mild effects such as dizziness, nausea, headaches, and fatigue.[1] In some studies, doses as high as 75 mg have been used without any serious adverse effects reported.[2]
It’s worth noting that there are some concerns regarding the safety of melatonin in young children and infants. In a report by the CDC, melatonin ingestion by children resulted in a number of hospitalizations between 2012 and 2021, including at least two infants who ultimately died.[3]