Melatonin exposures reported to Texas poison centers in 1998-2003.

Melatonin regulates circadian rhythms, and although widely used in the US, information on the public use of melatonin and patterns of reported adverse effects associated with the substance is limited. To describe the patterns of melatonin calls to poison centers in Texas during 1998-2003, data on all melatonin calls reported to the Texas Poison Center Network were analyzed. During 1998-2003, there were 779 identified human exposures to melatonin identified. Of those patients with a known age, 59.1% were < 6 y. Males accounted for 54.1% of preschool-age patients while more of the older patients were female. Melatonin exposures were unintentional in 99.3% of the cases among children less than 6y and unintentional in < 41% among the older age groups. While 92.4% of exposures involving theyoungest age group were managed outside of a health care facility, 42% or less of the exposures occurring to patients > age 6 years were managed outside of a health care facility. Of those cases with a known outcome, the proportion of cases with at least minor effects rose with increasing age. The majority of melatonin exposures reported to Texas poison centers involved children < 6 y. Younger patients were more likely to be male, have unintentional exposures, have no clinical effect, and to not require management at health care facilities. The observed clinical effects and treatment methods were consistent with the literature.