Minoxidil and pericardial effusion: an idiosyncratic reaction.

Minoxidil is a new potent antihypertensive vasodilator. Although highly effective, its use is limited by the association of the drug with pericardial effusion. We examined possible relationships in 37 patients. There was no significant effusions identified by echocardiography in 22 patients under active treatment. Retrospective review of 15 additional patients no longer under treatment identified seven who had had effusion and one who had had transient pericarditis. Resolution of effusion accompanied withdrawal in five patients; rechallenge was followed by effusion in one patient. Ninety-one episodes of pericardial disease have been reported in 1,869 experimental subjects (4.8%). Pericardial tamponade occurred in 21, with eight associated deaths. There are no specific patient characteristics that predict the likelihood of effusion. Since the reaction is both idiosyncratic and potentially fatal, it seems appropriate to continue to limit the use of minoxidil.