Photoallergic skin reaction to ribavirin

A 65-yr-old woman with chronic hepatitis C was treated with three million units interferon-alpha t.i.w. and 1000 mg ribavirin daily. At wk 16 of combination therapy the patient developed an itchy eczematous erythema, partly of urticarial character, which was almost confined to ultraviolet (UV)-exposed sites. Histopathological examination of the skin lesions was consistent with a photoallergic reaction. The minimal erythematous dose for UVA and UVB was assessed on healthy skin. After 24 h, a distinct erythema at the UVB irradiated site was found, whereas no reaction was seen with UVA provocation up to a dose of 10 J/cm2. Correspondingly, determination of the absorption spectrum of ribavirin revealed maximum absorption within UVB at 282.5 nm. Ribavirin was stopped, and the cutaneous lesions and pruritus completely disappeared without subsequent hyperpigmentation. This case indicates that ribavirin is a potential photosensitizer for UVB, which may become increasingly relevant in patients with chronic hepatitis C undergoing combination therapy for 6-12 months with interferon-alpha and ribavirin.