Red man syndrome is most commonly associated with which antibiotic, particularly with rapid intravenous infusion?

• A. Amoxicillin
• B. Linezolid
• C. Vancomycin
• D. Ceftriaxone

Answer: (C)

Red man syndrome is a histamine-mediated reaction that occurs with rapid IV infusion of vancomycin. When the infusion is too fast, mast cells release histamine, leading to flushing of the face and upper body, sometimes with itching, rash, and occasionally low blood pressure or tachycardia. It’s not a true drug allergy, but a rate-related infusion reaction. Slowing the vancomycin infusion dramatically reduces the risk, and pretreatment with an antihistamine can help in certain cases. To prevent it, vancomycin should be infused over at least 60 minutes (often longer, such as 90–120 minutes for larger doses). The other antibiotics listed do not typically cause red man syndrome as a primary infusion reaction.