Adverse events in long-term studies of exogenous melatonin.

Although the reported frequency of possible adverse events associated with long-term melatonin use is low and few clinically significant adverse events have been reported, the scarcity of data from double-blind randomized placebo-controlled trials should caution against complacency. Ideally, analysis of data from large well-established research databases should be conducted to provide good quality evidence on which to base a more rigorous evaluation of the safety profile.