Can i take bactrim (sulfamethoxazole and trimethoprim) (amoxicillin generic) 24hrs after plan b pill and still have the pill be as effective?

Yes: Neither Bactrim (sulfamethoxazole and trimethoprim) nor amoxicillin (the two are different types of antibiotics) should alter the effectiveness of Plan B. Taking Plan B or other emergency contraception pills can alter the timing or quality of the current menstrual cycle bleeding and perhaps the upcoming cycle. One should check a urine pregnancy 3 weeks after taking Plan B, as Plan B works most of the time but not all of the time.