Abstract: We included 12 studies, all of which enrolled adult participants with frequent episodic TTH. Nine used the IHS diagnostic criteria, but two used the older classification of the Ad Hoc Committee, and one did not describe diagnostic criteria but excluded participants with migraines. While 3094 people with TTH participated in these studies, the numbers available for any form of analysis were lower than this; placebo was taken by 733, standard ibuprofen 200 mg by 127, standard ibuprofen 400 mg by 892, and fast-acting ibuprofen 400 mg by 230. Participants had moderate or severe pain at the start of treatment. Other participants were either in studies not reporting outcomes we could analyse, or were given one of several active comparators in single studies. For the IHS-preferred outcome of being pain free at 2 hours the NNT for ibuprofen 400 mg (all formulations) compared with placebo was 14 (95% confidence interval (CI), 8.4 to 47) in four studies, with no significant difference from placebo at 1 hour (moderate quality evidence). The NNT was 5.9 (4.2 to 9.5) for the global evaluation of 'very good' or 'excellent' in three studies (moderate quality evidence). No study reported the number of participants experiencing no worse than mild pain at 1 or 2 hours. The use of rescue medication was lower with ibuprofen 400 mg than with placebo, with the number needed to treat to prevent one event (NNTp) of 8.9 (5.6 to 21) in two studies (low quality evidence). Adverse events were not different between ibuprofen 400 mg and placebo; RR 1.1 (0.64 to 1.7) (high-quality evidence). No serious adverse events were reported. Ibuprofen 400 mg provides an important benefit in terms of being pain free at 2 hours for a small number of people with frequent episodic tension-type headache who have an acute headache with moderate or severe initial pain. There is no information about the lesser benefit of no worse than mild pain at 2 hours.

Plain-language summary: We searched the literature in January 2015 and found 12 studies involved 3094 participants. Of these, about 1800 were included in comparisons between ibuprofen 400 mg and placebo. Others involved lower doses of ibuprofen, or different types of ibuprofen, or were in comparisons with other active drugs. The outcome preferred by the International Headache Society (IHS) is being pain free after two hours. This outcome was reported by 23 in 100 people taking ibuprofen 400 mg, and in 16 out of 100 taking placebo. The result was statistically significant, but only 7 people (23 minus 16) in 100 benefited specifically because of ibuprofen 400 mg. The IHS also suggests a range of other outcomes, but few were reported consistently enough for them to be used. People with pain value an outcome of having no worse than mild pain, but this was not reported by any study. About 4 in 100 people taking ibuprofen 400 mg had an adverse event with ibuprofen, the same as with placebo. There were no serious adverse events. There are questions about how studies in this type of headache are conducted. These questions involve the type of people chosen for the studies, and the outcomes reported. This limits the usefulness of the results, especially for people who just have an occasional headache.