For those who are using caffeine to help relieve a migraine (or more generally, a vascular headache) I would suggest looking into the possibility that you might be *addicted* to *caffeine* and it is the side effects and/or withdrawal symptoms that could be part of the root cause of your headache difficulty. YMMV. I am speaking from personal experience! I was physically addicted to caffeine for at least 20 years and I managed to figure out that caffeine withdrawal was causing a very severe and fully disabling headache every Sunday afternoon. Onset of withdrawal symptoms starts around 48 hours after the last dose. Complete withdrawal recovery took me about *3 weeks* of gradual dosage reductions (weaning) while going through headache hell the whole time. Caffeine is not a solution, it is at least a part of the problem.
I have a frequent episodic migraine pattern where I have migraines for several days in a row, then relief for several days. My migraine diagnosis was by the use of Imitrex, which worked the first time I tried it in about 1995 (about 6 years after the caffeine washout and discontinuation), and has worked reliably ever since. Other medications have had intolerable side effects and a couple of the preventives caused what I claim to be longer lasting medication injury.