I have confirmed migraine diagnosis and if taken in time, imitrex (sumatriptan) works. can one build a tolerance to the imitrex (sumatriptan) drug needing to up the dose?

Tolerance to the med: The best way to treat migraine is prevention, either by avoiding trigger mechanisms or medications tryptans are the only meds that can be taken even when the headache is ongoing .Read the drug insert tolerance to this type of medication is unlikely.

Yes: If you take triptan meds more than 8 days a month on average you can develop medication overuse headache aka rebound headache which is a state when abortive meds don't work as well and preventatives are less effective as well. A headache diary is a key component of managing migraine.

In some cases: There are two situations where we sometimes see a decline in effectiveness of imitrex (sumatriptan). 1. Over time, some people will note a drop in its effectiveness. 2. Rebound headaches, in which frequent consumption of Imitrex (sumatriptan) (more than 2-3 days per week) will start to cause your migraines to return more often. Fortunately, there are several other medications in the same family ("triptans") that work well.