A Migraine that lasts 72 hours or longer with less than a solid four-hour pain-free period, while awake, is termed status Migrainous. You should see your doctor or go to the emergency room if a Migraine lasts that long. See Status Migrainous - The Basics for more information.   If you're asking about an injection to use when you know a Migraine is coming but hasn't started yet, no, there is not.   There are two Migraine abortives in injection form that can be taken as soon as a Migraine starts. Imitrex and DHE-45 are injections that you can give yourself at home. You can read more about the Imitrex injections HERE.   Good luck, Teri