Can one build a tolerance to imitrex (sumatriptan)?  

In a way. There does seem to be a waxing and waning effect of many headache medications, and a drug that works well for years can become less effective with time. In addition, using Imitrex (sumatriptan) more than 2-3 times per week can lead to the development of a medication overuse headache, which is very difficult to effectively treat. You may wish to consider adding a prophylactic medication.
Yes. If used frequently Triptan medicines like imitrex (sumatriptan) can become less effective. In some cases rebound headaches can occur with analgesics like Advil as well as with Triptans. Migraines can be transformed into chronic daily headaches due to overuse of headache medicines. .
Not uncommon. This is but one reason we have so many triptans, as response is very variable, tolerance does develop and some patients do NOT even respond, making it necessary to try alternative abortives such as ergotamines or Cambia.

Related Questions

Can a person who takes Imitrex (sumatriptan) for migraines build a tolerance to the drug?  having to eventually increase dose or change medications?

Is it the right med? I have seen many, many people who do not respond to typical migraine medications (imitrex, relpax, (eletriptan) maxalt, etc) because they don't have true migraines. Often time any bad headache is diagnosed as a migraine. There are many other types of headaches that can be just as bad (tension, cluster, rebound, etc) that do not respond to those treatments. Confirm that your diagnosis is correct first! Read more...
Maybe. But a more accurate explanation is that you may be treating the wrong condition with the wrong med. Since many people have mixed headache patterns, and since most bad headaches come out of the neck, these pain patterns will not respond to triptans. Many people have secondary migraines where the triptan will help, but if more of your pain is from other comditions, then you will need different tx. Read more...