Efficacy and safety of acetaminophen and naproxen in the treatment of tension-type headache. A randomized, double-blind, placebo-controlled trial.

The objective of this study was to evaluate and compare the efficacy and safety of single doses of acetaminophen (paracetamol) 1000 mg and naproxen 375 mg vs. placebo over a six-hour period in the treatment of tension-type headache. The treatments were compared in a randomized, double-blind, multicentre, placebo-controlled study. Efficacy was evaluated using four standard analgesic summary endpoints (the sum of pain intensity differences from baseline, the maximum pain intensity from baseline, the sum of the pain relief scores, and the maximum pain relief score). Both acetaminophen 1000 mg and naproxen 375 mg were significantly superior to placebo (P<or=0.009 and P<or=0.021, respectively) but not significantly different from each other (P>or=0.498) for these four endpoints. For example, the mean sum of pain intensity differences from baseline was 9.14+/-0.34 for acetaminophen 1000 mg and 8.81+/-0.35 for naproxen 375 mg compared with 7.42+/-0.34 for placebo. Other efficacy endpoints (percentage of responders (pain reduced to none) at two hours, onset of meaningful relief, time to use of rescue medication and subject's overall impression of study medication) showed similar trends. A significantly larger mean pain intensity difference from baseline was observed for acetaminophen 1000 mg (1.13) than for naproxen 375 mg (0.95) (P=0.036) at one hour after treatment. There was no significant difference among the treatment groups in the incidence of adverse events (P=0.730). In summary, the results of this well-controlled, double-blind study demonstrate that over-the-counter acetaminophen 1000 mg and prescription naproxen 375 mg are effective and well tolerated in the treatment of tough (moderate-to-severe) tension-type headache.