Hi Hallie... You didn't say what kind of medicine you were taking that you believe is causing your yeast infections. The most common ones are: antibiotics, high estrogen contraceptives, immunosuppressant drugs, and steroids. I couldn't find anything in the literature that antihistamines, the most common allergy medicine, cause yeast infections. I would encourage you to talk with your doctor about the best approaches. However, you can also try a nasal rinse, which flushes out mucus and allergens from your nasal passages. You can buy one at your local drugstore or even make your own, with the recipe here: http://altmedicine.about.com/cs/allergiesasthma/a/SinusIrrigation.htm