Amitriptyline
"I don't take this on a regular basis because it knocks me out and I quickly build a tolerance.  I do take it once a regular headache passes that point of no return. While I'm quite anti-prescription medicines I would die without this (or have outrageous ER bills).  I average 6 serious (vomiting, neck cramps, loss of coherence, etc.) migraines a month. I take this as soon as I start getting my typical symptoms of a bad one and it knocks me for an hour or 2. I wake up and feel great. A little groggy for the next hour or 2, but what a fair trade.  Beats sitting in an ER for 4 hours waiting for the magic shot."