Paracetamol, also known as acetaminophen and APAP, is a medication used to treat pain and fever. It is typically used for mild to moderate pain relief. There is mixed evidence for its use to relieve fever in children. It is often sold in combination with other medications, such as in many cold medications. Paracetamol is also used for severe pain, such as cancer pain and pain after surgery, in combination with opioid pain medication. It is typically used either by mouth or rectally, but is also available by injection into a vein. Effects last between 2 to 4 hours.

Paracetamol is generally safe at recommended doses. The recommended maximum daily dose for an adult is 3 or 4 grams. Higher doses may lead to toxicity, including liver failure. Serious skin rashes may rarely occur. It appears to be safe during pregnancy and when breastfeeding. In those with liver disease, it may still be used, but in lower doses. It is classified as a mild analgesic. It does not have significant anti-inflammatory activity. How it works is not entirely clear.

Paracetamol was first made in 1877. It is the most commonly used medication for pain and fever in both the United States and Europe. It is on the World Health Organization's List of Essential Medicines, which lists the most effective and safe medicines needed in a health system. Paracetamol is available as a generic medication with trade names including Tylenol and Panadol, among others. The wholesale price in the developing world is less than US$ 0.01 per dose. In the United States, it costs about US$0.04 per dose. In 2016, it was the 17th most prescribed medication in the United States, with more than 29 million prescriptions.

The American College of Rheumatology recommends paracetamol as one of several treatment options for people with arthritis pain of the hip, hand, or knee that does not improve with exercise and weight loss. A 2015 review, however, found it provided only a small benefit in osteoarthritis.

Based on a systematic review, paracetamol is recommended by the American Pain Society as a first-line treatment for lower back pain. In contrast, the American College of Physicians found good evidence for NSAIDs but only fair evidence for paracetamol, while other systematic reviews have concluded that evidence for its efficacy is lacking entirely.

NSAIDs such as ibuprofen, naproxen, and diclofenac are more effective than paracetamol for controlling dental pain or pain arising from dental procedures; combinations of NSAIDs and paracetamol are more effective than either alone. Paracetamol is particularly useful when NSAIDs are contraindicated due to hypersensitivity or history of gastrointestinal ulceration or bleeding. It can also be used in combination with NSAIDs when these are ineffective in controlling dental pain alone. The Cochrane review of preoperative analgesics for additional pain relief in children and adolescents shows no evidence of benefit in taking paracetamol before dental treatment to help reduce pain after treatment for procedures under local anaesthetic, but the quality of evidence is low.

Paracetamol is used to treat patent ductus arteriosus, a condition that affects newborns when a blood vessel used in developing the lungs fails to close as it normally does, but evidence for the safety and efficacy of paracetamol for this purpose is lacking. NSAIDs, particularly indomethacin and ibuprofen, have also been used, but the evidence for them is also not strong. The condition appears to be caused in part by overactive prostaglandin E2 (PGE2), signalling primarily through its EP4 receptor, but possibly also through its EP2 receptor and EP3 receptors.

Acute overdoses of paracetamol can cause potentially fatal liver damage. In 2011, the U.S. Food and Drug Administration launched a public-education program to help consumers avoid overdose, warning: "Acetaminophen can cause serious liver damage if more than directed is used." In a 2011 Safety Warning, the FDA immediately required manufacturers to update labels of all prescription combination acetaminophen products to warn of the potential risk for severe liver injury and required that such combinations contain no more than 325 mg of acetaminophen. Overdoses are frequently related to high-dose recreational use of prescription opioids, as these opioids are most often combined with acetaminophen. The overdose risk may be heightened by frequent consumption of alcohol.

Paracetamol is metabolised by the liver and is hepatotoxic; side effects are multiplied when combined with alcoholic drinks, and are very likely in chronic alcoholics or people with liver damage. Some studies have suggested the possibility of a moderately increased risk of upper gastrointestinal complications such as stomach bleeding when high doses are taken chronically. Kidney damage is seen in rare cases, most commonly in overdose.

As of 2014, the American Academy of Pediatrics and the National Institute for Health and Care Excellence continue to recommend paracetamol for pain and discomfort in children, but some experts have recommended that paracetamol use by children with asthma or at risk for asthma should be avoided.