Læknablaðið 2004; 90: 545-51

The knowledge of drug side-effects is an important part of modern medicine and it is thought that about 25% of all side effects are based on activation of the immune system. Unlike most other side effects, immune responses to drugs are usually unforeseen and minimally or not at all related to their dosage. Such activation is not only based on the pharmacological character of the drug but also various environmental factors and the individual?s genetic makeup.

Allergy is traditionally categorized into the four groups of Gell and Coombs. Such allergy is usually based upon specific activation of certain cells through antibody receptors on the cell-surface but the immune system can also be activated unspecifically, irrespective of antibody receptors, through pharmacological actions or by unknown mechanisms. Non-steroidal anti inflammatory drugs (NSAIDs) can cause allergic reactions either directly or indirectly. Because of the extensive usage and usefulness of NSAIDs in medicine, these allergic side effects cause a large and difficult problem within the health system.

This article discusses in depth the causes and pathology of the different disease forms caused by immune reactions to NSAIDs, with emphasis on describing why some people with asthma may feel a serious, temporary worsening of the disease after ingestion of NSAIDs. Finally, diagnostic approaches to NSAID allergies are discussed.