cluster headaches
"I note that this is US based, but thought we could make this trans-Atlantic.  I was VERY lucky in that my GP diagnosed cluster headaches very early on and referred me to a Neurologist.  I was having an average of 7-8 headaches a day.  Have been on 480mg a day (2 x 240mg a day) for a month and half now.  Major improvement in about 10 days.  Now I am having only a couple a day and they are not as intense.  Oxygen at the onset usually clears it, otherwise I have to use a sumatriptan injection (but not very often).  Would very much advise verapamil as treatment.  The side effects are annoying but better than the excruciating pain."