Famotidine 為廣為使用之H2 接受器阻斷劑，主要治療與預防消化道潰瘍，治療濃度範圍大，副作用小，交互作用也咸少發生。顆粒性白血球減少症發生之機率小於1%。本案例為53 歲男性，有第2 型糖尿病合併腎病變等病史，每週三次規則洗腎。2015 年9 月2 日至本院就醫時，血液檢查顯示白血球 (white blood cell, WBC) 計數為1,220 cell/μL、嗜中性白血球 (neutrophil) 僅占4.9%。住院期間血液檢查報告發現病人有嚴重顆粒性白血球減少症 (granulocytopenia)，懷疑與famotidine 相關，降低famotidine 劑量，次日停藥。於給與白血球生成素 (filgrastim 300 μg/0.7 ml) 11 個劑量後，白血球計數上升至13,940 cell/μL，絕對嗜中性白血球為9,700 cell/μL。


Famotidine, a frequently prescribed H2-receptor antagonist, is generally well tolerated with low incidence of adverse effects. Famotidine-induced neutropenia and granulocytopenia are rare, and only a few cases have been reported. A 53-year-old man had been regularly receiving dialysis three times a week. On September 2, 2015, the patient was admitted to the nephrology department with the white blood cell (WBC) count of 1,220 cell/μL and the percentage of neutrophil of only 4.9%. During hospitalization, granulocytopenia was reported. After reviewing medication profile, famotidine was suspected and its dose was immediately tapered, followed by discontinuing the drug the next day. After receiving filgrastim 300 µg/0.7 ml, the patient’s WBC count returned to 13,940 cell/μL on September 9, 2015.