What is levothyroxine? Levothyroxine is a thyroid medicine that replaces a hormone normally produced by your thyroid gland to regulate the body's energy and metabolism. Levothyroxine is used to treat hypothyroidism (low thyroid hormone). This medicine is given when your thyroid does not produce enough of this hormone on its own. Levothyroxine is also used to treat or prevent goiter (enlarged thyroid gland), which can be caused by hormone imbalances, radiation treatment, surgery, or cancer. Warnings You may not be able to take levothyroxine if you have certain medical conditions. Tell your doctor if you have an untreated or uncontrolled adrenal gland disorder, a thyroid disorder called thyrotoxicosis, or if you have any recent or current symptoms of a heart attack. Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of this medicine, especially if you are taking any other weight-loss medications or appetite suppressants. Before taking this medicine Levothyroxine should not be used to treat obesity or weight problems. Dangerous side effects or death can occur from the misuse of levothyroxine, especially if you are taking any other weight-loss medications or appetite suppressants. Since thyroid hormone occurs naturally in the body, almost anyone can take levothyroxine. However, you may not be able to take this medicine if you have certain medical conditions. Tell your doctor if you have: an untreated or uncontrolled adrenal gland disorder; a thyroid disorder called thyrotoxicosis; or symptoms of a heart attack (chest pain or heavy feeling, pain spreading to the jaw or shoulder, nausea, sweating, general ill feeling). To make sure levothyroxine is safe for you, tell your doctor if you have ever had: a thyroid nodule; heart disease, a blood clot, or a blood-clotting disorder; diabetes (insulin or oral diabetes medication doses may need to be changed when you start taking this medicine); kidney disease; anemia (lack of red blood cells); osteoporosis, or low bone mineral density; problems with your pituitary gland; or any food or drug allergies. Tell your doctor if you have recently received radiation therapy with iodine (such as I-131). If you become pregnant while taking levothyroxine, do not stop taking the medicine without your doctor's advice. Having low thyroid hormone levels during pregnancy could harm both mother and baby. Your dose needs may be different during pregnancy. Tell your doctor if you are breastfeeding. Your dose needs may be different while you are nursing. Do not give this medicine to a child without medical advice. Tirosint is not approved for use by anyone younger than 6 years old. How should I take levothyroxine? Take levothyroxine exactly as it was prescribed for you. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Levothyroxine oral is taken by mouth. The injection is given as an infusion into a vein. Levothyroxine is usually given by injection only if you are unable to take the medicine by mouth. Levothyroxine oral works best if you take it on an empty stomach, 30 to 60 minutes before breakfast. Follow your doctor's dosing instructions and try to take the medicine at the same time each day. Swallow the tablet or capsule whole, with a full glass (8 ounces) of water. The tablet may dissolve very quickly and could swell in your throat. Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon). Levothyroxine doses are based on weight in children. Your child's dose needs may change if the child gains or loses weight. It may take several weeks before your body starts to respond to levothyroxine. Keep using this medicine even if you feel well. You may need to use this medicine for the rest of your life. You may need frequent medical tests. Tell any doctor, dentist, or surgeon who treats you that you are using this medicine. Store at room temperature away from moisture and heat. Do not share this medicine with another person, even if they have the same symptoms you have.   What happens if I miss a dose? Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. What happens if I overdose? Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Overdose symptoms may include headache, leg cramps, tremors, feeling nervous or irritable, chest pain, shortness of breath, and fast or pounding heartbeats. What to avoid Avoid the following food products, which can make your body absorb less levothyroxine: grapefruit juice, infant soy formula, soybean flour, cotton seed meal, walnuts, and high-fiber foods. Levothyroxine side effects Get emergency medical help if you have signs of an allergic reaction to levothyroxine: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have: fast or irregular heartbeats; chest pain, pain spreading to your jaw or shoulder; shortness of breath; fever, hot flashes, sweating; tremors, or if you feel unusually cold; weakness, tiredness, sleep problems (insomnia); memory problems, feeling depressed or irritable; headache, leg cramps, muscle aches; feeling nervous or irritable; dryness of your skin or hair, hair loss; irregular menstrual periods; or vomiting, diarrhea, appetite changes, weight changes. Certain side effects may be more likely in older adults. Common levothyroxine side effects may include: chest pain, irregular heartbeats; shortness of breath; headache, leg cramps, muscle pain or weakness; tremors, feeling nervous or irritable, trouble sleeping; increased appetite; feeling hot; weight loss; changes in your menstrual periods; diarrhea; or skin rash, partial hair loss. This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.   What other drugs will affect levothyroxine? Many other medicines can be affected by your thyroid hormone levels. Certain other medicines may also increase or decrease the effects of levothyroxine. Certain medicines can make this medicine less effective if taken at the same time. If you use any of the following drugs, avoid taking them within 4 hours before or 4 hours after you take levothyroxine: calcium carbonate (Alka-Mints, Caltrate, Os-Cal, Oyster Shell Calcium, Rolaids Soft Chew, Tums, and others); cholestyramine, colesevelam, colestipol; ferrous sulfate iron supplement; sucralfate; sodium polystyrene sulfonate (Kalexate, Kayexalate, Kionex); stomach acid reducers - esomeprazole, lansoprazole, omeprazole, rabeprazole, Nexium, Prilosec, Prevacid, Protonix, Zegerid, and others; or antacids that contain aluminum or magnesium - Gaviscon, Maalox, Milk of Magnesia, Mintox, Mylanta, Pepcid Complete, and others. Many drugs can interact with levothyroxine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

What is liothyronine? Liothyronine is a man-made form of a hormone that is normally produced by your thyroid gland to regulate the body's energy and metabolism. Liothyronine is given when the thyroid does not produce enough of this hormone on its own. Liothyronine treats hypothyroidism (low thyroid hormone). Liothyronine is also given as part of a medical test for thyroid disorders. Liothyronine is also used together with surgery and radioactive iodine therapy in people with thyroid cancer. Liothyronine should not be used to treat obesity or weight problems. Liothyronine may also be used for purposes not listed in this medication guide. Warnings Liothyronine should not be used to treat obesity or weight problems. You may not be able to use liothyronine if you have an adrenal gland problem that is not controlled by treatment. Stop taking liothyronine and call your doctor if you have symptoms of thyroid toxicity, such as chest pain, fast or pounding heartbeats, feeling hot or nervous, or sweating more than usual. Before taking this medicine Since thyroid hormone occurs naturally in the body, almost anyone can take liothyronine. However, you may not be able to use this medicine if you have an adrenal gland problem that is not controlled by treatment. Tell your doctor if you have ever had: problems with your pituitary or adrenal gland; heart disease, angina (chest pain); a bleeding or blood clotting disorder; diabetes; or osteoporosis or low bone mineral density. Tell your doctor if you are pregnant or breastfeeding. Follow your doctor's instructions about using this medicine if you are pregnant. Controlling your thyroid hormone levels is very important during pregnancy, and your dose needs may be different during each trimester. How should I take liothyronine? Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed. Older adults may be more sensitive to the effects of liothyronine, and doses are generally lower for people in this age group. If you are switching to liothyronine from any other thyroid medicine, stop using the other medicine before you start taking liothyronine. Liothyronine doses are based on weight (especially in children and teenagers). Your dose needs may change if you gain or lose weight. When given as part of a thyroid suppression test, you will need to take liothyronine for several days in a row in preparation for the test. Tell your doctor if you miss any doses during this time. Your thyroid function will need to be tested often. Even if you have no symptoms, tests can help your doctor determine if this medicine is effective. If you need surgery, tell your surgeon you currently use this medicine. You may need to stop for a short time. This medicine can affect the results of certain medical tests. Tell any doctor who treats you that you are using liothyronine. Keep using this medicine as directed, even if you feel well. You may need to take thyroid medication for the rest of your life. Store at room temperature away from moisture and heat.   What happens if I miss a dose? Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time. What happens if I overdose? Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Overdose symptoms may include headache, sweating, diarrhea, irregular menstrual periods, confusion, weakness, swelling in your hands or feet, fast heart rate, chest pain, feeling short of breath, fainting, or feeling nervous, restless, or irritable. What should I avoid while taking liothyronine? Do not change brands or change to a generic product without first asking your doctor. Different brands of liothyronine may not work the same. If you get a prescription refill and your new pills look different, talk with your pharmacist or doctor. Liothyronine side effects Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat. Stop using liothyronine and call your doctor if you have symptoms of thyroid toxicity, such as chest pain, fast or pounding heartbeats, feeling hot or nervous, or sweating more than usual. Also call your doctor at once if you have: weak or shallow breathing; confusion; a feeling of being cold all the time; changes in weight or appetite; chest pressure spreading to your jaw or shoulder; a light-headed feeling, like you might pass out; severe headaches, ringing in your ears, dizziness, vision problems, pain behind your eyes; a seizure; or (in a child or teenager) pain, stiffness, and trouble moving the legs. Common side effects may include: trouble breathing; headache; tremors, feeling nervous or irritable; muscle weakness; increased appetite; diarrhea; irregular menstrual periods; weight loss; feeling hot; rash; or sleep problems (insomnia). This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.   What other drugs will affect liothyronine? Some medicines can make liothyronine much less effective when taken at the same time. If you take any of the following medicines, take your liothyronine dose 4 hours before you take the other medicine. cholestyramine; colesevelam; colestipol; or sevelamer. Tell your doctor about all your current medicines. Many drugs can affect liothyronine, especially: cancer medicine; birth control pills or hormone replacement therapy; cough or cold medicine; an antidepressant; steroid medicine; seizure medicine; insulin or oral diabetes medicine; or a blood thinner (warfarin, Coumadin, Jantoven). This list is not complete and many other drugs may affect liothyronine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.