Schytz HW, Wienecke T, Olesen J & Ashina M. Carbachol induces headache, but not migraine-like attacks, in patients with migraine without aura. Cephalalgia 2009. London. ISSN 0333-1024Carbachol induces headache in healthy subjects, but the migraine eliciting effect of carbachol has not previously been studied. We hypothesized that the cholinomimetic agonist carbachol would induce headache and migraine-like attacks in migraineurs. Carbachol (3 microg/kg) or placebo was randomly infused into 18 patients with migraine without aura in a double-blind crossover study. Headache was scored on a verbal rating scale from 0 to 10. Velocity in the middle cerebral artery (V(MCA)) and diameter of the superficial temporal artery (STA) were recorded. Fifteen patients experienced headache after carbachol compared with eight after placebo (P = 0.039). There was no difference in incidence of migraine-like attacks after carbachol (n = 8) compared with placebo (n = 6) (P = 0.687). Carbachol caused a decrease in V(MCA) (P = 0.044), but no change in STA (P = 0.089) compared with placebo. The study demonstrated that carbachol provocation is not a good model for experimental migraine.