7 DRUG INTERACTIONS Avoid using clindamycin phosphate and benzoyl peroxide gel in combination with topical or oral erythromycin-containing products because of its clindamycin component. ( 7.1 ) 7.1 Erythromycin Clindamycin phosphate and benzoyl peroxide gel should not be used in combination with topical or oral erythromycin-containing products due to its clindamycin component. In vitro studies have shown antagonism between erythromycin and clindamycin.
Source: FDA drug label - clindamycin phosphate and benzoyl peroxide