Incompatibility of diphenhydramine hydrochloride (Benadryl) with meglumine iodipamide (Cholografin).

Diphenhydramine hydrochloride (Benadryl) and meglumine iodipamide (Cholografin) were mixed in varying proportions and found to consistently form a dense amorphous precipitate. This is not mentioned in the package insert of either agent. All physicians who administer these compounds should be aware of this phenomenon.