I started taking my pill day 1 (the start of my period), but I had been on Trimethoprim Sulfamethoxazole since day 1 of the month and I got my period on day 3 of this month. I took my dose for7 days, so I ended on the 7th. On the 9th (just ending my period) I had unprotected sex (never missed a pill, always on time). I know now that I should have waited 7 days off of medication to have unprotected sex. I want to know the reaction that microgestin has with Trimethoprim-Sulfamethoxazole and if they're commonly used together, haven't doctors minimized the reaction?