Adverse reactions of PDE5 inhibitors: An analysis of the World Health Organization pharmacovigilance database.

Phosphodiesterase type 5 inhibitors show significant signals correlating with priapism among a large international cohort. Further clinical study is needed to elucidate whether this is from proper or inappropriate use or other confounding conditions, as analysis of pharmacovigilance data does not allow for quantifying the clinical risk. Also, there appears to be a relationship between phosphodiesterase type 5 inhibitor use and malignant melanoma, which warrants additional study to better understand causation.