Liothyronine Sodium

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Nov 03, 2023

Warnings


Liothyronine Risks, Warnings, and Complications


Liothyronine can cause serious health problems in some people. Talk to your doctor about other treatment options for hypothyroidism (underactive thyroid) if you are at an increased risk of serious adverse effects from this medicine. Some of the risks of taking liothyronine include:

  • NOT FOR WEIGHT LOSS: Thyroid hormones can cause weight loss as a side effect. However, liothyronine should not be used to achieve weight loss or treat obesity. This medication does not promote weight loss in people with normal thyroid function. Thyroid hormone overtreatment can cause serious side effects in people with a normally functioning thyroid gland, especially if they are on other medications for weight loss.

  • CARDIAC ADVERSE EFFECTS: In people with underlying cardiovascular disease, overtreatment with thyroid hormone can cause worsening heart problems, especially in elderly individuals. Your doctor will start you on a lower dose of Cytomel (liothyronine) if you are at risk of heart problems. Tell your doctor without delay if you develop chest pain, a rapid or irregular heartbeat, or shortness of breath while on this medicine. If you develop cardiovascular symptoms, your provider may recommend you reduce the dose or discontinue thyroid hormone for one week and restart it at a lower dose.

  • MYXEDEMA COMA: This is a life-threatening emergency associated with slowed metabolism and poor circulation. It can cause unpredictable thyroid hormone absorption from the gastrointestinal tract. Oral thyroid hormone products such as liothyronine are therefore not recommended to treat myxedema coma. Instead, intravenous products are used to treat this condition. 

  • ADRENAL CRISIS: In people who have low thyroid hormones and low adrenal hormones (uncorrected adrenal insufficiency), replacing the thyroid hormones first can cause the adrenal hormone levels to drop even further. Before starting treatment with liothyronine, your healthcare provider will check adrenal hormone levels and prescribe glucocorticoids if they are low. Tell your doctor right away if you develop weakness, stomach pain, nausea, vomiting, loss of appetite, fever, dizziness, or confusion while on Cytomel (liothyronine). 

  • CYTOMEL DOSE ADEQUACY: Cytomel (liothyronine) has a narrow therapeutic index (a small range of an apparent adequate replacement dose). Overtreatment or undertreatment with this medicine can have negative effects. Your healthcare provider will ensure that the thyroid hormone dose is carefully titrated. They will monitor your response after you have your Cytomel dosage adjusted by ordering blood tests to measure thyroid hormone parameters. This can help prevent undertreatment (incomplete treatment of hypothyroidism) or overtreatment (hyperthyroidism). Follow your doctor’s dosing instructions carefully. Keep in mind that drug or food interactions can affect thyroid hormone metabolism. 

  • WORSENING DIABETES CONTROL: In people with diabetes, taking thyroid hormone liothyronine can result in worsening control of blood glucose levels and the need to increase the dose of antidiabetic medications, including insulin. Talk to your doctor about how often you should monitor your blood sugar levels after starting, adjusting, or discontinuing liothyronine.

  • DECREASED BONE DENSITY: Thyroid hormone over-replacement can result in increased bone resorption and decreased bone mineral density. The risk is especially high in post-menopausal women and those taking higher doses or taking liothyronine for a longer duration. The increase in bone resorption can result in increased serum calcium and phosphorus levels, increased urinary excretion of these minerals, elevation in bone alkaline phosphatase, and suppression of serum parathyroid hormone levels. To lower the risk of these complications, your doctor will prescribe Cytomel therapy at the lowest effective dose.


Precautions Before Starting Liothyronine

Tell your doctor if you have ever had an allergic reaction to liothyronine, other thyroid medications such as levothyroxine, any of the active or inactive ingredients in Cytomel tablets, or any other medications. Your pharmacy can give you a list of ingredients.

Give your doctor and pharmacist a complete list of your medications, including prescription drugs, non-prescription medicines, vitamins, nutritional supplements, and herbal products. This can help avoid possible drug interactions between liothyronine and your other medications.

Give your doctor a complete medical history. Liothyronine may not be right for people with certain medical conditions such as adrenal insufficiency, thyrotoxicosis, diabetes, high blood pressure, or cardiovascular disease, including coronary artery disease, heart attack, angina (chest pain), or an irregular heart rhythm. 

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding.

Precautions During Use of Liothyronine

Keep all your medical and lab appointments while on liothyronine. Your doctor may want to order certain medical tests and monitor you for adverse reactions.

If you are on cholesterol-lowering medications such as cholestyramine (Questran), colesevelam, or colestipol, a medication used to treat high potassium called Kayexalate, or a medication prescribed to dialysis patients called sevelamer, make sure you take these medications at least 4-5 hours away from your liothyronine dose. 

Tell your healthcare professional if you become pregnant while on liothyronine.

Tell all your healthcare providers you are on liothyronine, including before any surgical procedures or dental treatments.

Liothyronine Drug Interactions

Interactions between liothyronine and other medications can affect how they work. Possible drug interactions can increase your risk of serious adverse reactions. Your doctor may change the dose of your medications and/or monitor you carefully for side effects if there are known interactions between liothyronine and your other medicines. The following medications can have interactions with thyroid hormone therapy:

  • Oral anticoagulants or blood thinners such as warfarin (Coumadin, Jantoven)
  • Insulin and oral medications used to treat diabetes 
  • Heart medications such as digoxin (Lanoxin)
  • Estrogen-containing oral contraceptives 
  • Tricyclic antidepressants such as amitriptyline (Elavil)

Give your doctor or pharmacist a complete list of your medications, including prescription drugs, non-prescription medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription medicines.