Polyethylene glycols (PEGs) are commonly utilized as a bowel prep prior to colonoscopy. They are generally well-tolerated, and reports of allergic reactions are rare. A recent search of the literature reveals only 4 prior reported cases of allergic reactions and only 1 other case of anaphylaxis. We report a second case of anaphylaxis following the ingestion of PEG solution, making this the fifth reported case of an allergic reaction to PEG bowel prep.