I am having troble with repeat migraines lasting 3-4 days,
Headache goes away after taking imitrex but then returns next day.
Doctor is changing from Imitrex to Relpax??
Triptans such as Imitrex and Relpax work by binding to serotonin receptors. Each of the seven triptans binds to different combinations of serotonin receptors. That's why one may be more effective for a Migraineur than another.
The intended results are the same -- stopping the Migrainous process in the brain, which also stops the symptoms.
I am not sure how they differ on a chemical level.
I used to have a perscription for both imitrex and relpax. You can never mix them (so they are obviously different in some way) but I alternated so I didn't get as bad of rebound headaches or build up a tolerance.
I have always thought that imitrex was stronger. I took the relpax for minor migraines and imitrex for really bad ones. You might be getting a higer dose of the relpax...and everyone is different anyway.
Physically I found no difference between the way the two medications made me feel. They are both pretty effective. I think you'll like it. Hope it stops them from coming back the next day :)