1例46岁女性类风湿性关节炎患者因营养性巨幼细胞性贫血给予叶酸10 mg口服、3次/d。首次服药后约8 min，患者出现全身皮肤瘙痒，随即头面部、四肢、躯干部出现弥漫性斑丘疹。考虑为叶酸引起的速发型过敏反应，停用叶酸，给予氯苯那敏4 mg口服。但患者皮肤症状加重，继而出现气促、胸闷、恶心等症状。立即给予地塞米松、10%葡萄糖酸钙、异丙嗪和吸氧等对症治疗。40 min后，患者皮肤瘙痒缓解；5 h后，皮疹消退；7 h后，过敏症状消失。给予氯苯那敏治疗3 d后，行叶酸脱敏治疗，未再出现不良反应，患者贫血逐渐改善。继续口服氯雷他定和叶酸。随访1个月，患者无不适，血红蛋白113.5 g/L，停药，嘱患者于风湿科就诊治疗类风湿性关节炎。“,”A 46-year-old female patient with rheumatoid arthritis received oral folic acid 10 mg thrice daily for nutritional megaloblastic anemia. About 8 minutes after the first administration, the patient developed itchy skin all over the body, followed by diffuse macular papules on the head, face, limbs, and trunk. Considering the immediate anaphylaxis caused by folic acid, folic acid was discontinued and chlorphenamine 4 mg was given orally. However, her skin symptoms were aggravated, followed by shortness of breath, chest tightness, nausea, and etc. Symptomatic treatments with dexamethasone, 10% calcium gluconate, promethazine, and oxygen inhalation were given immediately. Forty minutes later, her itchy skin was relieved; 5 hours later, the rashes subsided; and 7 hours later, the allergic symptoms disappeared. After 3 days of treatment with chlorphenamine, folic acid desensitization treatment was performed. Then no adverse reactions recurred and the patient′s anemia was gradually improved. The patient continued to took oral loratadine and folic acid. At 1 month of follow-up, she had no discomfort, and the laboratory tests showed hemoglobin 113.5 g/L. Drugs were stopped and the patient was instructed to visit the department of rheumatology for the treatment of rheumatoid arthritis.