How the interaction occurs:
The cause of this interaction is not known. When these two medicines are taken together, dextrothyroxine may decrease the ability of your blood to form clots.
What might happen:
You may experience an increased chance for bleeding including bleeding from your gums, nosebleeds, unusual bruising, or dark stools.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) as soon as possible about taking these two medicines together. They may already be aware of this drug interaction and may be monitoring you for it. If your doctor prescribes these medicines together, you may need to check your bleeding times more often. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Walters MB. The relationship between thyroid function and anticoagulant therapy. Am J Cardiol 1963 Jan;11:112-4.
2.Schrogie JJ, Solomon HM. The anticoagulant response to bishydroxycoumarin. II. The effect of D- thyroxine, clofibrate, and norethandrolone. Clin Pharmacol Ther 1967 Jan-Feb;8(1):70-7.
3.Kimberg DV. The liver. In: Werner SC, Ingbar SH, ed. Werner and Ingbar's The thyroid. New York: Harper & Row; 1971: 569..
4.Feely J, Stevenson IH, Crooks J. Altered plasma protein binding of drugs in thyroid disease. Clin Pharmacokinet 1981 Jul-Aug;6(4):298-305.
5.Weintraub M, Breckenridge RT, Griner PF. The effects of dextrothyroxine on the kinetics of prothrombin activity: proposed mechanism of the potentiation of warfarin by D-thyroxine. J Lab Clin Med 1973 Feb; 81(2):273-9.
6.Owens JC, Neely WB, Owen WR. Effect of sodium dextrothyroxine in patients receiving anticoagulants. N Engl J Med 1962 Jan 11;266(2):76-9.
7.Self T, Weisburst M, Wooten E, Straughn A, Oliver J. Warfarin-induced hypoprothrombinemia. Potentiation by hyperthyroidism. JAMA 1975 Mar 17; 231(11):1165-6.
8.Rice AJ, McIntosh TJ, Fouts JR, Brunk SF, Wilson WR. Decreased sensitivity to warfarin in patients with myxedema. Am J Med Sci 1971 Oct;262(4):211-5.
9.Vagenakis AG, Cote R, Miller ME, Braverman LE, Stohlman F Jr. Enhancement of warfarin-induced hypoprothrombinemia by thyrotoxicosis. Johns Hopkins Med J 1972 Jul;131(1):69-73.
10.Gotta AW, Sullivan CA, Seaman J, Jean-Gilles B. Prolonged intraoperative bleeding caused by propylthiouracil-induced hypoprothrombinemia. Anesthesiology 1972 Nov;37(5):562-3.
11.Piziak VK, Hahn HB Jr. Isolated menarche in juvenile hypothyroidism. Clin Pediatr (Phila) 1984 Mar;23(3):177-9.