Allergic contact dermatitis caused by gum rosin and wood rosin in Tako-no-Suidashi ointment.

Tako-no-Suidashi ointment (TSO) is an old Japanese over-the-counter drug, used for the drainage of infectious pustular disease, such as furuncles, carbuncles and infectious atheroma, although whether it works well or not is unknown. The ingredients of the TSO compound commonly include rapeseed oil, gum rosin, wood rosin, Japanese wax, paraffin, petrolatum, copper sulfate, Peru balsam, acetic acid, salicylic acid and trace amounts of Guinea green B. We report a case of contact dermatitis in a 38-year-old Japanese woman caused by TSO. The patient presented to our hospital with pruritic erythema on her left cheek. In order to remove a subcutaneous tumor, she had applied TSO 4 days prior to presentation. Clinical examination showed a well-demarcated exudative erythematous macule with yellowish crusts and scales on her left cheek. Patch testing showed a positive reaction to TSO (++), gum rosin (++) and wood rosin (++) at 72 h. As TSO includes highly allergenic material, caution should be made in applying this topical therapy.