Thirteen studies were included in the review: ten cross-over RCTs (299 patients), two parallel RCTs (194 patients) and one cohort study (5,692 participants). All included trials were considered to have a high overall risk of bias.
Paracetamol versus placebo (three trials): All three trials demonstrated statistically significant effects in favour of paracetamol for mean pain relief over a six hour period.
Paracetamol versus NSAID (four trials): All four trials indicated a benefit of NSAID over paracetamol for pain relief, but the results were not clearly reported by the trial authors.
Paracetamol versus weak opioids (three trials): None of the trials showed a difference between paracetamol and weak opioids for pain relief.
Paracetamol plus NSAID versus placebo plus NSAID (two trials): One trial that evaluated different dosages of indomethacin (NSAID) and found no difference in mean pain or tolerability between the two different treatment groups. Another trial compared paracetamol plus naproxen versus placebo plus naproxen, and found significantly less pain with the combined treatment, but no difference in tolerability.
There were no significant differences in total adverse events or withdrawals due to adverse events between the treatment arms in eight out of ten of the trials that reported safety data. Among the two remaining trials, findings were mixed (reported fully in paper). The cohort trial found no differences in the incidence of serious gastrointestinal events between patients taking different single analgesics (paracetamol, acetylsalicylic acid or ibuprofen). There was an increased rate of serious gastrointestinal events with paracetamol over acetylsalicylic acid or ibuprofen (when used concurrently with corticosteroids and one of the other analgesics).