Thyroid Hormone Medicines for Hypothyroidism

Browse By All Topics


Thyroid Hormone Medicines for Hypothyroidism


Generic NameBrand Name
levothyroxine (T4)Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid
liothyronine (T3)Cytomel
liotrix (T3 and T4) Thyrolar

Thyroid hormones are taken by mouth (orally) except in unusual cases, such as myxedema coma. That condition requires intravenous (IV) medicine. Dosages vary with the person's age and the severity of the disease.

How It Works

People with hypothyroidism have lower-than-normal or no thyroid function and do not make enough thyroid hormone for the body to function properly. Taking thyroid hormone medicine replaces missing hormones.

Why It Is Used

Thyroid hormone medicines are given when blood tests show that you have hypothyroidism.

Thyroid hormone medicines also may be prescribed:

How Well It Works

People with hypothyroidism who take thyroid hormone medicine usually notice:

  • Improved energy level.
  • Gradual weight loss (in people with severe hypothyroidism at the time of diagnosis).
  • Improved mood and mental function (thinking, memory).
  • Improved pumping action of the heart and improved digestive tract function.
  • Reduction in the size of an enlarged thyroid gland (goiter), if you have one.
  • Improved growth, school performance, and behavior in children. Children whose growth has been delayed because of hypothyroidism start growing normally again when they are getting adequate doses of thyroid hormone.
  • Lower cholesterol and triglyceride levels.

In most cases, thyroid hormone medicine works quickly to correct symptoms.

Myxedema coma can respond well to thyroid hormone medicine and treatment in an intensive care unit. But a good outcome depends on how soon treatment starts.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.
  • Chest pain.

Call your doctor if you have:

  • Hives.
  • Heart palpitations.
  • Nervousness.
  • Trouble sleeping (insomnia).
  • Shaking (tremors).
  • Frequent bowel movements or diarrhea.
  • Too much weight loss.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Certain medicines can affect the way thyroid medicines work. People taking the following medicines need to see their doctor often to make sure they are getting the correct dose of thyroid hormone medicine. Some of these medicines include:

  • Calcium. Take calcium supplements at least 4 hours before or after taking thyroid hormone medicine.
  • Iron supplements.
  • Birth control pills or other hormones.
  • Cholestyramine.
  • Sucralfate and some antacids containing aluminum hydroxide.
  • Some seizure medicines.
  • Some antibiotics used to treat tuberculosis.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Specialist Medical ReviewerMatthew I. Kim, MD - Endocrinology
Last RevisedAugust 7, 2012

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use.

How this information was developed to help you make better health decisions.

© 1995-2012 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.