Intravenous Methylcobalamin-Induced Anaphylactic Shock: A Case Report

BACKGROUND: Methylcobalamin is a naturally occurring, active form of Vitamin B12. Vitamin B12 is essential for the growth and development of healthy nerves and red blood cell production. Usually, the requirement of vitamin B12 is increased in thyrotoxicosis due to increased utilization and accelerated turnover imposed by increased metabolism. Vitamin B12 is generally well-tolerated and widely used in clinical settings. Parenteral vitamin B12 treatment in hospitalized patients is considered an effective therapy regardless of its etiology. CASE PRESENTATION: Herein, we report the case of a 26-year-old female patient admitted to the Obstetrics and Gynaecology department. She received a slow intravenous methylcobalamin injection on the 4th day of admission for his complaints. Then, she was administered with 2nd dose of intravenous methylcobalamin, after which she developed anaphylactic shock immediately. To address these serious adverse effects, the patient was administered Critical care with cardiopulmonary resuscitation without further delay. The patient had a spontaneous return of circulation within a few minutes of high-quality cardiopulmonary resuscitation. After treatment, the patient recovered and was discharged from the hospital. CONCLUSION: Anaphylactic shock, after slow intravenous methylcobalamin injection, is an uncommon but potentially serious adverse effect. The purpose of this case report is to highlight the importance of this rare but serious life-threatening adverse effect. To our knowledge, this is the first reported case of intravenous methylcobalamin-induced anaphylactic shock. Physicians and healthcare teams should be cautious while administering methylcobalamin to patients, especially via the intravenous route.