Doctor told me to take 1 nitrofurantoin after & before intercourse. within how many hours afterwards should i be taking it for it to be effective?

UTI prophylaxis: Nitrofurantoin Rxd for you to take before and after intercourse is mostly likely most likely is because you had been having recurrent UTIs after intercourse and this should decrease the number that you have. Since it is a medication that would normally have to be Rxd 4 times per day for regular treatment take the second dose within 6 hours after the first dose you took before intercourse.