Immediate hypersensitivity reaction to polyethylene glycol 3350

Polyethylene glycol (PEG) 3350 is the main ingredient of oral solutions for bowel preparation prior to colonoscopy. This high-molecular-weight PEG has shown a low incidence of adverse reactions because of its low absorption via the intestine. Systemic allergic reactions to PEG solution are very rare, and only 10 cases have been reported in the literature worldwide. We experienced a case of immediate hypersensitivity reaction to PEG 3350. A 35-year-old male patient was prescribed PEG 3350 solution for colonoscopy. After ingestion of 2.5 pack (55 g of PEG 3350 powder), he began to show urticaria on both arms and trunk, and swelling in the lips. Symptoms resolved over the next few hours without any treatment. Skin prick and intradermal tests with PEG 3350 showed positive responses to both test. We also performed oral provocation tests with PEG 3350. Thirty minutes after ingestion of 2.5 g of PEG 3350 powder, the patient presented with mild urticaria and angioedema. Finally he was diagnosed with immediate hypersensitivity reaction by PEG 3350. The patient underwent colonoscopy after preparation with sodium phosphate solution without any adverse reactions. We herein report the first case of PEG 3350-induced immediate hypersensitivity reaction confirmed by skin and oral provocation tests in Korea.