Several studies have reported general symptoms, including dizziness, headache, nausea, and agitation. However, these were equally common in the treatment and placebo groups and couldn’t be attributed to melatonin. It also doesn’t seem to cause any dependence or withdrawal symptoms.
It is generally considered safe to take melatonin gummies supplements even in high doses in the short term. More research into its long-term safety, however, is required, particularly in children.