Ranitidine is generally safe in pregnancy. Anaphylaxis is rarely observed with ranitidine. Anaphylaxis is triggering maternal hypotension leading to intrapartum hypoxic-ischemic encephalopathy in the infant. Furthermore, cesarean sections are performed at a high rate of anaphylactic pregnant woman. A 43-year-old primigravida was hospitalized for a cesarean section at 38+3 weeks of gestation. She didn’t have any underlying disease. She had histories of drug allergy for common cold medication. But she didn’t know exactly what drugs were causing allergies. Following admission, before the cesarean section, ranitidine was injected to her. At the beginning of the injection, the patient complained of dizziness, and within seconds she experienced shortness of breath and chest tightness. Several minutes later she experienced dyspnea, sweating, and severe cramping pain in the abdomen. Further, the fetal heart revealed bradycardia (70-80 beats per minute). She has received an emergency cesarean section under general anesthesia. A male infant weighing 3220 g was delivered with Apgar scores of 2 and 3 and 4 at 1, 5 and 10 minutes. The infant was transferred to the neonatal intensive care unit. After the surgery, the mother was received routine post-operation care and discharged home. We report a case who developed severe anaphylaxis following a single dose of intravenous ranitidine in the rare case.