Conjugated estrogens and Propylthiouracil interaction
Conjugated estrogens and Propylthiouracil: the Conjugated estrogens prescribing label describes an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Conjugated estrogens (Premarin) label · effective 2025-05-30
Hypothyroidism Estrogen administration leads to increased thyroid-binding globulin (TBG) levels.
Women with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T 4 and T 3 serum concentrations in the normal range.
Women dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy.
These women should have their thyroid function monitored in order to maintain their free thyroid hormone levels in an acceptable range.
Increased thyroid-binding globulin (TBG) leading to increased circulating total thyroid hormone, as measured by protein-bound iodine (PBI), T 4 levels (by column or by radioimmunoassay) or T 3 levels by radioimmunoassay.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.