Introduction. This fact sheet provides an overview of selected ingredients in dietary supplements designed or claimed to enhance exercise and athletic performance. There are no vitamins made specifically for people with hypothyroidism who take Synthroid. The best vitamin for you is the one that includes the correct amount of vitamins and minerals that you need to supplement your diet or that you may need for any other underlying health issues. Synthroid (levothyroxine) is a moderately priced drug used to treat hypothyroidism. It also treats an enlarged thyroid gland and thyroid cancer. Hypothyroidism. Synthroid is indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. Learn about Synthroid (Levothyroxine Sodium) may treat, uses, dosage, side effects, drug interactions, warnings, patient labeling, reviews, and related medications. Medical use. Levothyroxine is typically used to treat hypothyroidism, and is the treatment of choice for people with hypothyroidism, who often require lifelong thyroid hormone therapy. Doses of levothyroxine that normalize serum TSH may not normalize LDL cholesterol and total cholesterol. Synthroid (levothyroxine sodium) and Tirosint (levothyroxine sodium) are synthetic compounds identical to T4 (levothyroxine) produced by the human thyroid gland used to treat hypothyroidism due to many causes (for example: thyroid removal, thyroid atrophy, functional T4 deficiency, radiation treatment of the thyroid, and other causes). USE. SYNTHROID® (levothyroxine sodium) tablets, for oral use is a prescription, man-made thyroid hormone that is used to treat a condition called hypothyroidism. Foods containing soy and cottonseed meal can make Synthroid less effective. Walnuts, grapefruit juice, and dietary fiber can also make Synthroid less effective. Save money when safely buying Synthroid online. PlanetDrugsDirect is a safe and secure Canadian international prescription referral service.