Four RCTs were included for review (n=241 participants), of which one was double-blind, double-dummy (n=51 participants) and one was double dummy (n=83 participants). There was a discrepancy between the number of participants reported for the trials and the number included for analysis, which was unexplained by the authors.
There was no significant difference between oral and rectal acetaminophen in temperature reduction at one (WMD -0.14 degrees centigrade, 95% CI: 0.36 to 0.08; four RCTs, n=124 participants) or three hours (WMD -0.10 degrees centigrade, 95% CI: -0.41 to 0.21; four RCTs, n=124 participants) after administration, in the maximum temperature reduction achieved (WMD -0.10 degrees centigrade, 95% CI: -0.24 to 0.04; two RCTs, n=81 participants) or in the time taken to a temperature reduction of one degree centigrade (WMD -0.06 degrees centigrade, 95% CI: -1.34 to 1.23; two RCTs, n=71 participants). There was evidence of significant statistical heterogeneity for time taken to temperature reduction (p<0.001, I2=94.8%) but no evidence of significant statistical heterogeneity was found for the other outcomes.
Only one trial was found measuring pain, so a meta-analysis of pain reduction was not performed.