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.