Which of the following is a known side effect of vancomycin?

• A. Red man syndrome
• B. Hyperglycemia
• C. Hair loss
• D. Nosebleed

Answer: (A)

Red man syndrome is the classic infusion-related adverse effect of vancomycin. It happens when the drug is given too quickly IV and triggers rapid histamine release, causing flushing and erythema of the face, neck, and upper body. It’s not a true allergy, but it can feel alarming, so the usual fix is to slow the infusion (often administering the dose over at least 60 minutes or longer) and consider an antihistamine if needed. If symptoms are more severe, pausing the infusion and addressing any low blood pressure or itching is important before restarting at a slower rate. Other options listed—hyperglycemia, hair loss, or nosebleeds—are not typical side effects of vancomycin.