Seven Cases of Anaphylaxis to Paracetamol

Background: Paracetamol (acetaminophen, N-acetyl-para-aminophenol) is a well-known antipyretic and analgesic drug. Hypersensitivity reactions to paracetamol are rare. However, we report seven cases of anaphylaxis to paracetamol and a review of the literature. Procedure: Between January 1999 and May 2012, we diagnosed seven cases of anaphylaxis to paracetamol in our Allergy Department of Hospital Central de la Cruz Roja (Madrid, Spain). During these years, we reviewed our database for all cases identified as anaphylaxis due to paracetamol. We diagnosed anaphylaxis to paracetamol in seven patients: six women (85.71%) and one man (14.28%). Diagnosis was based on a detailed anamnesis history, skin prick tests (SPT), intradermal tests (IDT), and oral-challenge test (OCT). We also examined whether patients tolerated aspirin in order to confirm or rule out intolerance to NSAIDs. Results and Conclusions: We report seven cases of anaphylaxis to paracetamol. Although the results of skin testing were inconclusive, the reactions to paracetamol in our patients seem to be due to an immunological mechanism-IgE mediated. As all of our patients tolerated aspirin, the reactions were not related to cyclooxygenase inhibition. Although paracetamol is usually considered a safe drug, hypersensitivity reactions are possible and should not be overlooked when performing a full allergy study.