Levoxyl is primarily prescribed to treat an underactive thyroid and a variety of thyroid problems (such as certain types of thyroid cancer). This synthetic drug is identical to the naturally occurring hormone levothyroxine (T4). Although most people tolerate the drug well, side effects are possible and may include insomnia, hair loss, and heart palpitations. Levoxyl comes in the form of a tablet and is taken once a day in the morning.
The thyroid gland makes two different thyroid hormones -- triiodothyronine (T3) and levothyroxine (T4). Usually, the thyroid gland produces much more T4 than T3 (however, T3 is much more active than T4). The body can convert the T4 hormone into T3 as necessary. If your thyroid does not make enough thyroid hormones, there are a few different ways to increase your levels.
Some forms of thyroid replacement combine both T3 and T4 (such as natural thyroid replacement made from pig thyroids). However, because the body converts T4 into T3 as needed, most people can successfully take just T4 (such as with Levoxyl). Alternatively, just T3 can be taken (with products such as Cytomel®). Currently, most people take just T4 products (such as Levoxyl).
Although it is synthetic, Levoxyl is identical to the naturally occurring hormone levothyroxine (also known as T4).
Written by/reviewed by: Kristi Monson, PharmD;Arthur Schoenstadt, MD
Last reviewed by: KristiMonson, PharmD;
List of references (click here):
Levoxyl [package insert]. Bristol, TN: King Pharmaceuticals, Inc.;2007 October.
Food and Drug Administration, Center for Drug Evaluation and Research. Electronic orange book: approved drug products with therapeutic equivalence evaluations. FDA Web site. Available at: http://www.fda.gov/cder/ob/. Accessed December 4, 2007.
Briggs GG, Freeman RK, Yaffe SJ. Drugs in Pregnancy and Lactation. 7th ed. Philadelphia (PA): Lippincott Williams & Wilkins;2005.
National Library of Medicine (US). Drugs and Lactation Database (LactMED). NLM Web site. Available at: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT. Accessed December 4, 2007.
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