Often, the blame for contraceptive failure is placed on a short stint of antibiotic use. Anecdotal reports abound regarding the reduction in pill effectiveness caused by antibiotics such as ampicillin and tetracycline, and some studies find lower levels of estradiol (a form of estrogen) in the blood of women taking these antibiotics, but no studies have been able to prove these claims. Studies are clear, however, regarding drug interactions between birth control pills and some other medications, such as anti-seizure medications and drugs used to treat tuberculosis. Ask your health care professional or pharmacist about possible drug interactions that may alter the effectiveness of either your birth control pills or another medication you are taking or are prescribed.