Doxycycline and Birth Control
All tetracycline antibiotics—including medications that contain doxycycline—are known to reduce the effectiveness of hormone-based birth control methods like pills, injections, patches and rings.
It is thought that these antibiotics affect the body’s ability to correctly absorb and use the hormones that are found in these birth control methods. This means that women who are taking Doxycycline should use an alternative form of contraceptive during their treatment with the antibiotics and for at least seven days afterward.
Condoms, sponges and diaphragms are the best alternative methods since they do not require the use of hormones to be effective.