Cimetidine and ranitidine may not cross-react to cause thrombocytopenia.

We report the case of a patient with peptic ulcer disease who developed cimetidine-induced thrombocytopenia. The thrombocytopenia resolved spontaneously following discontinuation of cimetidine, and did not recur with ranitidine. We concluded that cimetidine and ranitidine do not necessarily cross-react to induce thrombocytopenia. Thus the exclusion of both H2-blockers in the event that one has caused thrombocytopenia may not be justified.