Which of these antibiotics for cold interfere with yaz (drospirenone and ethinyl estradiol) (birth control pills) - cefalexin, ospen, amoxicillin, or any other in that category?

Penicillins mostly: Antibiotics may interfere with the effectiveness of birth control pills. Have they ever lead to failure of birth control? Not conclusively although it is theoretically possible. Mid cycle spotting could be a sign they are adversely affecting efficacy. Rifampin, Penicillins like Ospen and amoxicillin can do it. Cephalexin probably not. Stop them as soon as you can.