a lot of people that come to us for medicinal marijuana prescription use cannabis specifically for migranes.. the thing is, you have to learn which type of cannabis (indica or sativa) helps best for your migranes, and then you will find certain strains that work much better than others. for example, Haze is a great sativa, mostly used for chronic pain because it's mostly a body high, it relaxes your body without giving you a strong head high (like indicas would).

p.s.
for some people it's the opposite, you have to try different strains and compare the effects.