During rapid IV infusion of vancomycin, a patient develops flushing of the face, neck, and upper torso with pruritus but no bronchospasm or hypotension. The mechanism and correct management are:

• A Toxic accumulation of vancomycin dimers; reduce the total daily dose
• B IgE-mediated type I hypersensitivity; stop vancomycin permanently and switch to teicoplanin
• C Complement activation causing bradykinin release; administer epinephrine immediately
• D Direct histamine release from mast cells; infuse over at least sixty minutes and pretreat with an antihistamine if needed ✓

Explanation

Red man (red neck) syndrome is a rate-related, non-immunologic reaction caused by osmotic activation of mast cells releasing histamine directly, without IgE involvement. It is prevented by slowing the infusion to one hour or longer and can be treated with antihistamines such as hydroxyzine; the drug need not be stopped permanently. Absence of bronchospasm and hypotension argues against true anaphylaxis, so epinephrine is unnecessary, and the reaction is unrelated to dose size or complement activation.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.