Find patient medical information for Synthroid Oral on WebMD including its uses, side effects and safety, interactions, pictures, warnings and user ratings. Levothyroxine (Synthroid) is used for treating hypothyroidism, a condition in which the thyroid gland doesn't produce enough thyroid hormone. Uses. Levothyroxine is used to treat an underactive thyroid gland (hypothyroidism). It replaces or provides more thyroid hormone, which is normally produced by the thyroid gland. 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. Benefits of Thyroid Supplements They Help Control the Rate of Metabolism. One of the major functions of thyroid hormones is to regulate the metabolism rate. Thyroid supplements and metabolic supplements can be dangerous, but many take them for hypothyroidism. Consumer Reports explains what to watch out for. Iron supplements are used to treat iron deficiency and iron-deficiency anemia. Learn when you need the, how they are dosed, and how manage to side effects. Levothyroxine, a thyroid hormone, is used to treat hypothyroidism, a condition where the thyroid gland does not produce enough thyroid hormone.Levothyroxine is also used to treat congenital hypothyroidism (cretinism) and goiter (enlarged thyroid gland). Is taking certain supplements and hypothyroidism medications bad? Learn which supplements can interact with thyroid hormone medications like levothyroxine (Synthroid), thyroid hormone levels, and laboratory tests. Get Answers to Questions about Vitamins and Supplements.