Does topamax affect the birth control pill?

Estrogen, a common ingredient in Birth Control pills, increase the blood level of Thyroid Binding Globulin (TBG). Since TBG binds available thyroid hormone, a patient on birth control pills may have decreased levels of thyroid hormone. This is RARELY a problem, unless a patient has preexisting hypothyroidism. Of course, only your physician can detect this. **Medical Disclaimer: The information contained in this answer is provided for your general information only. I am, in no way, giving medical advice. I am not recommendending particular treatment for specific individuals and in all cases recommend that you consult your physician or before pursuing any course of treatment.**