Dipyrone for acute primary headaches: a Systematic Review

Introduction: Headaches commonly affect working-age people. Dipyrone is largely used in many countries. Objectives: To determine effectiveness/safety of dipyrone for adults with acute primary headaches. Method: Double blind randomized controlled trials systematic review. Dichotomous data were expressed as relative risks and risk differences, and continuous data as weighted mean differences. If possible, numbers-needed-to-treat were calculated. Results: Four studies were included (636 subjects). Meta-analysis was possible for one outcome, favouring dipyrone. Regarding episodic tension-type headache and migraine, individual studies data showed dipyrone statistically significant beneficial effect. No severe adverse events were reported. There was no statistically significant difference between dipyrone and placebo regarding mild to moderate adverse events. Conclusion: Dipyrone is effective in migraine and episodic tension-type headache. Conclusions about its safety and agranulocytosis can not be drawn probably due to the relatively small sample. If the results of a recent study, which is related to the incidence of agranulocytosis in Latin America, do not clarify the question, data from observational studies on dipyrone side effects should be searched to determine its safety.