Liothyronine, sold under the brand name Cytomel, is a T3 medication used by people with an underactive thyroid gland or hypothyroidism, states WebMD. Liotrix, sold under the brand name Thyrolar, contains both T3 and T4. Levothyroxine, sold under the brand names Synthroid, Levoxyl and Unithroid, is a thyroid replacement medication that contains only T4.
Patients with hypothyroidism do not produce enough thyroid hormone, which the body needs to function properly, explains WebMD. By taking T3 or T4 thyroid replacement medications such as liothyronine, liotrix or levothyroxine, hypothyroid sufferers are able to achieve normal thyroid levels and lead healthy lives. Additionally, T3 and T4 medications are sometimes prescribed to treat enlarged thyroid glands or goiters.
Patients who treat their hypothyroidism with thyroid medication should notice improved energy levels, weight loss, improved mental health, improved digestive function, and reduced levels of cholesterol and triglycerides, according to WebMD.
Patients taking thyroid medication should seek emergency medical help if they experience difficulty breathing; swelling of the face, tongue, lips or throat; or chest pain, advises WebMD. Patients taking thyroid medication should talk with their doctor if they experience hives, nervousness, difficulty sleeping, shaking, frequent bowel movements or excessive weight loss.
Calcium supplements, iron supplements, birth control pills, seizure medications, cholestyramine, antacids containing aluminum hydroxide and certain antibiotics can all affect the way that T3 and T4 thyroid medications work, according to WebMD.