Acetylsalicylic acid and acetaminophen.

Aspirin is the most extensively prescribed analgesic, antipyretic, and anti-inflammatory agent. It is effective against the mild-to-moderate pain of inflammation. The best single dose of aspirin is that which is adequate to relieve pain; the proper dosage interval is that which sustains relief without causing toxicity. It would be unfortunate to withhold aspirin from a patient who desperately requires the relief provided by this most useful analgesic because there have been some adverse effects when it is used improperly. Acetaminophen is a suitable substitute for aspirin for its analgesic or antipyretic uses in patients in whom aspirin is contraindicated (e.g., prepartum patients, children with febrile conditions, patients with asthma, peptic ulcer, gouty arthritis, hyperuricemia, hemophilia or other bleeding disorders, and those taking anticoagulants). However, the general substitution of acetaminophen for aspirin as an analgesic is not recommended.