D1.382 - Vitamin K–Induced Anaphylaxis: A Case Series from a Tertiary Hospital in Manila, Philippines (2024–2025)

Vitamin K–Induced Anaphylaxis: A Case Series from a Tertiary Hospital in Manila, Philippines (2024–2025)

Malizza Abigail H. Anzures-Custodio, MD and Remedios C. Ong, MD

Background

Vitamin K₁ (phytonadione) is widely used for coagulation disorders and is commonly administered intravenously in the Philippines, where oral formulations are not readily available. Although its package insert includes a boxed warning for severe anaphylactic reactions, reports of vitamin K–induced anaphylaxis are rare, and to our knowledge, no detailed local data have been published. 

Case Description

This case series describes three Filipino patients—two pediatric and one adult—who developed anaphylaxis after receiving intravenous vitamin K in a tertiary hospital in Manila, Philippines, between 2024 and 2025. 

The three patients had different underlying diagnoses and comorbidities, but all presented with abnormal bleeding parameters that prompted treatment. Only patient 1 had a history of atopy. Patients 2 and 3 previously tolerated vitamin K without adverse reactions. Patients 1 and 3 received the same brand of vitamin K, while patient 2 received a different one. All developed flushing, difficulty of breathing, and abdominal pain within minutes of intravenous vitamin K administration (1–4 mg infused at 0.05–1 mg/min), with reactions occurring at recommended infusion doses and rates. Patient  2 initially received an erroneously rapid infusion but developed anaphylaxis again during a subsequent properly administered vitamin K infusion. The patients responded promptly to intramuscular epinephrine, with adjunctive antihistamines and corticosteroids. Patient  1 underwent successful oral desensitization to injectable vitamin K using a 10-step protocol. Patients  1 and  2 tolerated oral maintenance doses of the parenteral formulation without recurrence of symptoms, while patient 3 required no further dosing. All patients were discharged stable, with no subsequent reactions observed.

Conclusion

Vitamin K–induced anaphylaxis, though rare, can occur even with slow, diluted intravenous infusion. Clinicians should recognize symptoms, stop the infusion, and give epinephrine promptly. Oral administration of injectable vitamin K allows gradual gastrointestinal absorption, likely reducing the risk of anaphylaxis. This may be a safe and effective alternative and should be preferred when feasible, reserving intravenous use for patients with significant vitamin K deficiency–related hemorrhage.

Keywords: vitamin K, vitamin K–induced anaphylaxis, phytonadione, oral vitamin K