FYI,

from headaches.about.com

DHE-45 (dihydroergotamine mesylate, USP) injectable is for the acute treatment of Migraine with or without aura. Ergotamine preparations are non-triptan Migraine abortives. Injectable medications bypass the gastrointestinal tract, making it appropriate for patients who suffer from nausea and vomiting as a result of migraine, and who may therefore have difficulty with oral treatments. DHE-45 is a migraine-specific serotonin agonist. It attacks migraine at its source by selectively binding to receptors in the brain that regulate the release of serotonin, a chemical thought to play a major role in the development of migraine.

Sorry to hear you are having such a difficult time with head aches.