Adverse cutaneous drug reactions to ibandronate.

Bisphosphonates are frequently used to treat bone diseases characterized by increased osteoclastic bone resorption. Adverse skin reactions to bisphosphonates are rare and range from benign to severe. Different cutaneous skin reactions have been reported with ibandronate in clinical and pharmacovigilance studies, from macula-papular rashes to toxic epidermal necrolysis. We report two new cases of erythematous and oedematous skin lesions to oral monthly ibandronate, appearing after multiple intakes of the drug. Prick tests were positive in both cases at 48 or 96 hours, and one could be confirmed histologically. Lesions did not relapse after substituting the culprit bisphosphonate with another one. A wide range of rare-to-very-rare adverse skin reactions exist with bisphosphonates, and especially ibandronate. We review the reported cases of adverse cutaneous drug reactions to bisphosphonates and illustrate the polymorphism and variety of the skin lesions. These reactions are not well known and may be misdiagnosed as they do not always suggest drug-induced eruptions. Furthermore, delays between drug intake and the first lesions can be misleading. The absence of cross-reactions among bisphosphonates allows substitution.