Toxicosis to 3 commonly available analgesics--ibuprofen, aspirin and acetaminophen--occurs in dogs and cats after acute ingestion or repetitive administration of therapeutic or excessive doses. Whereas in acute exposure, where the clinical course of an overdose to all 3 drugs is predictable in relation to the amount ingested, in chronic exposure to therapeutic doses of aspirin and ibuprofen, the development of gastric ulcers and analgesic nephropathy is unpredictable. Ibuprofen is not recommended for prolonged treatment in dogs and cats due to the likelihood of ulcer formation. Although gastric mucosal adaptation usually occurs with repeated therapeutic doses of aspirin, some individuals nevertheless develop gastric ulcers; simultaneous administration of the prostaglandin analogue misoprostol can reduce the risk. Following acute ingestion of aspirin or ibuprofen, treatment is essentially symptomatic and supportive following early decontamination procedures. Gastrointestinal protectants and i.v. fluids with sodium bicarbonate are generally recommended. Acetaminophen toxicosis is usually associated with single acute ingestion, and the primary target organs affected are the liver and the red blood cells in dogs and cats respectively. Because signs can progress rapidly with acute acetaminophen overdose, administration of N-acetylcysteine is always recommended, even when the history is unclear. This report summarizes the common clinical presentations of dogs and cats exposed to therapeutic or excessive doses of ibuprofen, aspirin or acetaminophen, and describes the treatment procedures advised by the ASPCA-National Animal Poison Control Center.