cluster headaches
"I'm on my 3rd recurrence of cluster headaches, and this time I managed to get to the doctor and renew my verapamil prescription right away, after my first attack, and it's worked immediately, I'm a solid week in now and have not gotten another attack, I'm on 80mg 3x per day.  It's worked well for me during past episodes, but I was really surprised that it controlled this recurrence so immediately."