Medications Used to Treat Thyroid Disease

Thyroid medications differ based on their intended use. For example, hormone replacement therapy, such as Synthroid (levothyroxine), is the most widely used drug for hypothyroidism (underactive thyroid).

On the other hand, an anti-thyroid drug, Tapazole (methimazole), may be used for hyperthyroidism (overactive thyroid).

In addition, people with thyroid cancer may require radioactive-iodine therapy or chemotherapy.

This article explains various thyroid conditions and the common medication treatments.

Hypothyroidism Medications

The role of the thyroid gland is to produce the hormones thyroxine (T4) and triiodothyronine (T3). These thyroid hormones regulate everything from heart rate and body temperature to respiratory function and menstrual cycles.

When the thyroid is underactive, it is called hypothyroidism. The thyroid gland may become underactive for numerous reasons, including:

• Hashimoto's disease (an autoimmune disorder)
• Iodine deficiency
• Thyroidectomy (surgical removal of the thyroid gland)

When your thyroid is underactive, it produces insufficient thyroid hormone. This deficiency leads to various symptoms that affect one or more organ systems. Symptoms can range in severity from mild to debilitating.

Treatment Goals

To restore sufficient thyroid hormone levels in the body, people with hypothyroidism usually take thyroid hormone replacement medication. However, medication may not be necessary for some circumstances, where an underactive thyroid gland is transient (temporary).

For example, some cases of thyroiditis (thyroid inflammation) are caused by reversible situations, such as a response to a medication, infection, or following pregnancy. Therefore, they may not require medication.

There are four main goals of thyroid hormone replacement medication:

• Alleviate symptoms of hypothyroidism
• Normalize the thyroid stimulating hormone (TSH) level
• Reduce the size of an enlarged thyroid (goiter) if present
• Avoid over-treatment (becoming hyperthyroid)

Levothyroxine

Levothyroxine—also called l-thyroxine and L-T4—is a synthetic form of the T4 (thyroxine) hormone. T4 is the storage hormone, which your body must convert into T3, the active hormone, for your cells to use.

Levothyroxine is the first-line treatment drug for treating hypothyroidism. In the United States, brand names include:

• Synthroid
• Levoxyl
• Unithroid
• Tirosint

Liothyronine

Liothyronine is a synthetic form of T3 (triiodothyronine). Brand names of liothyronine in the United States are Cytomel and Triostat.

For the most part, experts recommend T4-monotherapy (treatment with only T4) and not combination T4/T3 therapy for treating hypothyroidism. Therefore, healthcare providers do not commonly prescribe this medication.

Research is ongoing about whether combination T4/T3 therapy may benefit a subgroup of people with hypothyroidism who have a specific genetic mutation.

Natural Desiccated Thyroid

Natural desiccated thyroid—also known as NDT, natural thyroid, or porcine thyroid—is a prescription drug derived from the dried thyroid glands of pigs. NDT contains both T4 and T3.

Common brands are Armour Thyroid and Nature-throid. A generic is also available.

Most endocrinologists (doctors specializing in hormones) do not support or prescribe natural desiccated thyroid drugs. That is because they are combination drugs and because the ratio of T4 to T3 in animals does not match the ratio in humans. That said, certain select people may respond well to NDT.

Hyperthyroidism Medications

Hyperthyroidism means the thyroid gland is overactive, producing too much thyroid hormone. There are multiple causes of hyperthyroidism, including:

• Grave’s disease (an autoimmune disorder)
• Noncancerous thyroid nodules
• Thyroiditis
• Malfunctioning pituitary gland (which works in tandem with the thyroid gland)

Moreover, a phase of Hashimoto’s disease can also cause hyperthyroidism in the same way it causes hypothyroidism.

The treatment of hyperthyroidism is generally more complex than hypothyroidism, requiring one or more of the following treatments:

• Anti-thyroid drug
• Radioactive iodine (RAI)
• Thyroidectomy

The only medications for hyperthyroidism are anti-thyroid drugs. There are currently two approved for treating hyperthyroidism in the United States.

• Tapazole (methimazole, or MMI)
• Propylthiouracil (PTU)

Tapazole (methimazole)

The antithyroid drug Tapazole inhibits the thyroid from using iodine—usually from the diet—to produce thyroid hormone. You generally take this medication once a day.

Tapazole has fewer side effects and reverses hyperthyroidism more quickly than PTU. Its effectiveness makes it the preferred antithyroid drug choice.

Propylthiouracil (PTU)

Like Tapazole, PTU inhibits the thyroid gland from using iodine. Thus, it slows the overproduction of thyroid hormone. It also inhibits the conversion of the thyroid hormone T4 into T3.

PTU has a short-acting timespan. That means people taking this medication usually need to take the drug two to three times per day to effectively lower thyroid hormone levels.

PTU has more side effects than the other antithyroid drugs. Therefore, it is the preferred drug for hyperthyroidism only in a few situations, including:

• Early pregnancy
• Severe thyroid storm (when the body releases exceptionally high levels of thyroid hormones)
• Someone experiences serious side effects from Tapazole

Beta-Blockers

Beta-blockers, like Inderal (propranolol), block beta receptors that bind epinephrine (adrenaline). They are most commonly used for heart conditions and to prevent heart attacks.

With thyroid conditions, beta-blockers do not "treat" hyperthyroidism but rather reduce the body's symptoms of excess thyroid hormone like a fast heart rate, tremor, and anxiety.

Thyroid Cancer Medications

The primary treatment for most thyroid cancers is surgical thyroid removal. Sometimes removal involves the entire thyroid gland (total thyroidectomy) or just a lobe of the thyroid gland (lobectomy).

After surgery, you will require thyroid hormone replacement medication (levothyroxine) to replace thyroid hormone production and suppress tumor regrowth.

Levothyroxine

Levothyroxine for thyroid removal is used just as it is for other cases of underactive thyroid. Depending on the extent of the disease and your risk for recurrent thyroid cancer, a healthcare provider will determine what range TSH should be suppressed and adjust the levothyroxine accordingly.

Radioactive-Iodine Therapy

Sometimes radioactive-iodine therapy may be given after surgery. Circumstances in which it may be indicated include:

• Large thyroid cancers
• Thyroid cancer that has spread to the lymph nodes
• High risk for recurrent cancer

Radioactive iodine is given in a hospital setting in either liquid form or as a capsule. Its main goal is to kill off cancer cells after surgery and destroy any remaining thyroid tissue.

Chemotherapy

Chemotherapy, which works by killing rapidly dividing cancer cells, is not often used to treat thyroid cancer unless a person has recurrent or metastatic cancer (cancer that has spread).

Chemotherapy is also combined with external beam radiation for treating a rare type of thyroid cancer called anaplastic thyroid cancer.

Targeted Therapies

Scientists have developed several "targeted therapies"—drugs that target specific markers on cancer cells. Some of these drugs treat advanced or resistant thyroid cancer.

Nexavar (sorafenib) and Lenvima (lenvatinib) are two targeted therapies called kinase inhibitors. These medications partially block thyroid cancers from growing and making new blood vessels.

Summary

Which medication will treat your thyroid condition depends on your thyroid disease. Hypothyroidism is primarily treated with thyroid hormone replacement therapy, while hyperthyroidism is treated with antithyroid medicine. Thyroid cancers usually require surgical thyroid removal. Afterward, treatment may involve levothyroxine, radioactive iodine therapy, or chemotherapy.

A Word From Verywell

No doubt, being diagnosed with a thyroid condition can be overwhelming. But by gaining knowledge about the medications used to treat your disease, you are already taking the first step in your care.

Keep in mind, as you continue on your thyroid journey, you are not alone—and most of the time, thyroid conditions are managed well. Don't hesitate to update your healthcare provider on how you are feeling. There are many cases in which a person might benefit from an adjusted dose or even a drug change.

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