For half or more of people, one tablet never halves the pain
In pooled trials after surgery, 2.5 people had to take 400 mg of ibuprofen for one more to get half their pain gone over four to six hours. Diclofenac and naproxen sat at 2.7.
What the study found
Even the best single dose leaves half or more people short
In pooled single-dose trials after surgery, 2.5 people had to take 400 mg of ibuprofen for one more to get at least half their pain gone over four to six hours; diclofenac at 50 mg and naproxen at 500 mg both sat at 2.7. Across drugs and doses, half or more often never reached that.
The caveat · Mostly wisdom-tooth extraction pain
Most of the underlying data come from wisdom-tooth extraction in otherwise healthy adults, a standardised research model rather than everyday pain. These are single doses measured over four to six hours and say nothing about taking something repeatedly. The overview ran no statistical test between the drugs, so these numbers sit side by side and were never compared. Some drug and dose combinations were judged unreliable because of susceptibility to publication bias.