Aspirin and NSAID sensitivity.

Aspirin and the older nonsteroidal anti-inflammatory drugs (NSAIDs) that block cyclo-oxygenase-1 (COX-1) induce asthma attacks in patients with aspirin-exacerbated respiratory disease and urticaria in patients with chronic idiopathic urticaria. Weak inhibitors of COX-1, such as acetaminophen and salsalate, crossreact also but only with high doses of the drugs. Partial inhibitors of both COX-1 and COX-2, such as nimesulide and meloxicam, also cross-react but only at high drug doses. COX-2 inhibitors do not cross-react; however, all NSAIDs, including the selective COX-2 inhibitors, can sensitize patients and induce urticaria or anaphylaxis on next exposure to the drug.