Patient: If i have an underactive thyroid & i start taking tablets to treat it will it stop my combined pill working?
Doctor: Hello,Welcome to ATD. Thank you for the query.Thyroxine does not affect the combination pill action but the comb ined pills do affect thyroxine action.Estrogens tend to increase serum thyroxine-binding globulin (TBg). In a patient with a nonfunctioning thyroid gland who is receiving thyroid replacement therapy, free levothyroxine may be decreased when estrogens are started thus increasing thyroid requirements. Therefore, patients without a functioning thyroid gland who are on thyroid replacement therapy may need to increase their thyroid dose if estrogens or estrogen-containing oral contraceptives are given.So just let your doctor know that you are taking combination pills, so that he may adjust the thyroxine dose accordingly.Hope this helps. Take care