Im on tetrcycline and flamazine i heard and read they affect evra patch how much do they affect it? should i be qorried about getting.pregnant?

Little concern: While theoretically tetracyclines break down birth control pills faster which can cause breakthrough bleeding and/or result in pregnancy, this likelihood is considered so low that generally it is not advised to use a back up method (condoms) while on tetracyclines and the ortho evra patch. Also, hormone levels while on the ortho evra patch are on average higher than when on birth control pills.