Acetaminophen (paracetamol) is a widely prescribed analgesic-antipyretic drug. Adverse allergic reactions to this drug are rare. We report a case of anaphylactic shock due to acetaminophen. Results of skin prick tests and intradermal tests were negative. Oral rechallenge resulted in generalized urticaria associated with an increased plasma level of histamine. Acetaminophen should be added to the list of causes of anaphylaxis.