Vancomycin administration may cause which syndrome?

• A. Red Man Syndrome
• B. Stevens-Johnson Syndrome
• C. Serum Sickness
• D. Anaphylaxis

Answer: (A)

Vancomycin given by IV can trigger a histamine-release–mediated reaction if infused rapidly, known as Red Man Syndrome. It shows up as flushing and redness on the face, neck, and upper torso, sometimes with itching, and may be accompanied by low blood pressure or a fast heart rate during or right after the infusion. This occurs because the drug causes mast cells to release histamine when given too quickly, not because of an IgE allergy. Slowing the infusion rate (and sometimes giving an antihistamine) typically prevents or mitigates it. This distinguishes it from other reactions: Stevens-Johnson Syndrome is a severe, immune‑mediated mucocutaneous eruption; serum sickness is an immune complex–mediated reaction with fever, rash, and joint pains that appears later after exposure; anaphylaxis is an immediate, IgE‑mediated reaction with life-threatening airway and circulatory symptoms.