acetaminophen

Acetaminophen, also known as paracetamol, is a widely used analgesic and antipyretic. It is available in many over‑the‑counter and prescription forms and is included in numerous combination products. Unlike nonsteroidal anti-inflammatory drugs, acetaminophen provides pain relief and fever reduction but has limited anti-inflammatory effects at therapeutic doses.

Acetaminophen is used to treat mild to moderate pain such as headaches, muscle aches, and dental pain, and to reduce fever. It is generally well tolerated when used as directed. It does not relieve inflammation, so it is not considered an NSAID. It is commonly used in adults and children, including during pregnancy when used according to labeling.

Pharmacology and metabolism are such that acetaminophen is rapidly absorbed after oral administration and reaches peak blood levels within an hour. It is mainly eliminated by the liver through conjugation to glucuronide and sulfate forms; a small portion is metabolized by the cytochrome P450 system to a reactive intermediate (NAPQI) that is normally detoxified by glutathione. In overdose or when glutathione stores are depleted, NAPQI can cause liver injury. Chronic alcohol use or liver disease can increase risk. Acetaminophen can interact with other drugs, such as increasing warfarin’s anticoagulant effect with long-term use.

Dosing guidelines vary by age and weight. Adults commonly take 500–1000 mg every 4–6 hours, with a general maximum of 4000 mg per day (lower limits may apply for liver disease or alcohol use). Pediatric dosing is weight-based and should follow product labeling. In cases of suspected overdose, seek urgent medical care; the antidote is N-acetylcysteine. Safety profiles are favorable when used as directed.