ABSTRACT
In chemical structure idoxuridine closely approximates the configuration of thymidine, one of the four building blocks of DNA, the genetic material of the Herpes virus. Most literature on contact allergy to idoxuridine is at least 30 years old and it is doubtful whether this drug is still widely used. In Hungary, in the period 1996-2005, 133 patients with periorbital dermatitis were patch tested with 1% idoxuridine and there were 2 (1.5%) positive reactions; both were considered to be relevant. In Bari, Italy, in the period 1968-1983, 6 selected patients (selection procedure unknown) were patch tested with idoxuridine 0.5% pet. One patient had erythema multiforme/erythema multiforme-like contact dermatitis with erythematous urticarial papules, plaques and target-lesions from contact allergy to idoxuridine. One of 50 patients treated with 5% or 40% idoxuridine in DMSO became sensitized with acute allergic contact dermatitis; he later had positive patch tests to 1% and 5% idoxuridine in DMSO but not to DMSO alone.
