I recently used monistat 1 (tioconazole) ( last 2 1/2hrs) for a yeast infection and feel a slight burning sensation . is this normal and how long will it last?

Monistat is: OTC because it does not work up to current standards. some people are allergic to it and develop burning. i advise a cool tap water douche twice to rinse it out. then get an RX for diflucan or terazol (terconazole) to treat the infection.

Soon: You should be fine, but if not seeing your doctor for some tests might clarify the situation and suggest another treatment. A urine test might also be helpful. You might want to be see before the Labor Day weekend