Vitamin K1-Induced Anaphylactic Shock

Objective: To report a case of anaphylactic shock induced by the rapid intravenous administration of vitamin K1 in a patient in the intensive care unit (ICU). Case Summary: A 9-year-old Malay girl was admitted to the ICU and was diagnosed with Guillain-Barré syndrome. She developed an allergy to atropine that was manifested by a symmetric generalized transient macular rash over the trunk; it subsided 10 minutes after the drug was stopped. About 7 hours later, vitamin K1 10 mg iv was administered over 3 minutes due to the slight prolongation of prothrombin time and activated partial thromboplastin time. Immediately after the drug was administered, the patient developed a generalized transient macular rash, cyanosis, and shock. Her blood pressure and heart rate could not be detected. She responded well, however, after resuscitation. Discussion: Anaphylactic shock in this patient was most probably caused by the intravenous administration of vitamin K1, because this event occurred immediately after its administration. There have also been a few reported cases of severe reaction and death associated with intravenous administration of vitamin K1. The likelihood that the incident was drug-related could be classified as “probable” based on Naranjo's causal relationship algorithm. Conclusions: Rapid intravenous administration of vitamin K1 may induce anaphylactic shock in a critically ill patient with hemodynamic instability. If vitamin K1 is required, oral administration is preferred because it is rarely associated with severe reactions. Intravenous administration of vitamin K1 should be considered only in an emergency situation and the rate of administration should not exceed 1 mg/min.