Because caffeine is a vasodilator your body can become dependent on it so when you don’t have it your vessels constrict and can cause painful migraines. If caffeine dependency is what’s causing your migraines then weaning off it should stop them. I initially thought mine were caffeine dependent so I cut it out of my diet but that unfortunately wasn’t the cause for me. I still have to be careful not to develop a dependency but a little bit can help during some migraines but it’s a very fine balance to use it medicinally and not create an addiction.