Paracetamol is used for reducing fever in people of all ages. The World Health Organization recommends that paracetamol be used to treat fever in children only if their temperature is higher than 38.5 °C (101.3 °F). The efficacy of paracetamol by itself in children with fevers has been questioned and a meta-analysis showed that it is less effective than ibuprofen. Paracetamol does not have significant anti-inflammatory effects.
Paracetamol is used for the relief of mild to moderate pain. The use of the intravenous form for short-term pain in people in the emergency department is supported by limited evidence.
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.
Paracetamol has relatively little anti-inflammatory activity, unlike other common analgesics such as the nonsteroidal anti-inflammatory drugs (NSAIDs) aspirin, and ibuprofen, but ibuprofen and paracetamol have similar effects in the treatment of headache. Paracetamol can relieve pain in mild arthritis, but has no effect on the underlying inflammation, redness, and swelling of the joint. It has analgesic properties comparable to those of aspirin, while its anti-inflammatory effects are weaker. It is better tolerated than aspirin due to concerns about bleeding with aspirin.
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.
A joint statement of the German, Austrian, and Swiss headache societies and the German Society of Neurology recommends the use of paracetamol in combination with caffeine as one of several first-line therapies for treatment of tension and migraine headaches. In the treatment of acute migraine, it is superior to placebo, with 39% of people experiencing pain relief at 1 hour compared with 20% in the control group.
Paracetamol combined with NSAIDs may be more effective for treating postoperative pain than either paracetamol or NSAIDs alone.
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.
The efficacy of paracetamol when used in combination with weak opioids (such as codeine) improved for about 50% of people, but with increases in the number experiencing side effects. Combination drugs of paracetamol and strong opioids such as morphine improve analgesic effect.
The combination of paracetamol with caffeine is superior to paracetamol alone for the treatment of common pain conditions, including dental pain, post partum pain, and headache.
Patent ductus arteriosus
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.