I took Flucanazole for a chronic yeast infection and was prescribed one pill once a week for 3 weeks. After the 3 weeks, my periods became much lighter than usual. I was never told or asked if Flucanazole would make my birth control pills less effective and now am worried that what if I am pregnant because I didn't use protection the 3 weeks that I was on Flucanazole. My partner pulled out and I didn't use protection because didn't think the antifungal would affect my birth control pills.