7 DRUG INTERACTIONS Trimethoprim/sulfamethoxazole (TMP/ SMX) increases the level of dapsone and its metabolites ( 7.1 ) Topical benzoyl peroxide used at the same time as dapsone may result in temporary local yellow or orange skin discoloration. 7.1 Trimethoprim – Sulfamethoxazole A drug-drug interaction study evaluated the effect of the use of Dapsone Gel, 5%, in combination with double strength (160 mg/800 mg) trimethoprim-sulfamethoxazole (TMP/SMX).
Source: FDA drug label - dapsone gel, 5%