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.