Here are basic details about each of the medicines used to treat hypothyroidism. Only common side effects are listed. Ask your doctor if you need to take any special safety steps. Use each of these medicines the way you were taught by your care team. Call your doctor if you have any questions.
Levothyroxine is taken once a day. The dose you will take will depend on your test results, age, and weight. It is also based on whether you have any heart problems or any remaining thyroid gland. It can take time to find the right dose. The dose is slowly raised every 6 to 8 weeks until blood levels of TSH are in the normal range.
Older adults or people who have a heart problem will need to start with a lower dose. This will give your body a chance to get used to the higher thyroid hormone level. After you have reached normal levels of TSH, your doctor may want to see you at least twice a year to make sure your levels stay normal. Thyroid blood levels can get higher or lower over time. Your doctor may need to raise or lower your dose.
You may start to feel better in 1 to 2 weeks after you start taking medicine. It may take some people 3 to 6 months to feel better after blood levels become normal. You must keep taking levothyroxine. It is the only way to manage this health problem. Always take this medicine on an empty stomach with a full glass of water. Calcium, iron, soy, and multivitamins in the stomach will make it harder for your body to take in the medicine.
Stay on the same brand of levothyroxine. The same dose of some other brand may work differently in your body. If you change your dose or brand, you will be asked to have your blood levels of TSH checked about 6 weeks later.
Liothyronine (T3) is a short-acting thyroid hormone. It is not used as often as levothyroxine (T4). It is often given to patients after their thyroid is removed to treat thyroid cancer. It is sometimes used along with levothyroxine.
Both synthetic hormones are forms of thyroid hormones that are natural and needed in your body. Side effects may happen when you take too much.
If you take too much, it may cause:
Follow these medicine steps:
- Take your medicine as advised. Don't change the amount or schedule.
- Ask what side effects could happen. Tell your doctor if you have any.
- Talk to your doctor before you stop taking any prescription medicine.
- Don't share your prescription medicine.
- Medicines can be harmful when mixed. Talk to your doctor or pharmacist if you are taking more than one, including over the counter products and supplements.
- Plan for refills.
Franklyn JA, Boelaert K. Thyrotoxicosis. Lancet. 2012 Mar 24;379(9821):1155-66
Jonklaas J, Bianco AC, Bauer AJ, et al. Guidelines for the treatment of hypothyroidism. Thyroid. 2014 Dec;24(12):1670-751.
Hypothyroidism (underactive thyroid). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/endocrine-diseases/hypothyroidism. Updated August 2016. Accessed May 20, 2019.
Hypothyroidism in adults. EBSCO DynaMed website. Available at:http://www.dynamed.com/topics/dmp~AN~T115914/Hypothyroidism-in-adults. Updated July 20, 2018. Accessed May 20, 2019.
Last reviewed March 2019 by EBSCO Medical Review BoardJames P. Cornell, MD Last Updated: 5/20/2019