Thyroid medications are drugs used to control symptoms related to various forms of thyroid disease. Some of these drugs shrink the thyroid. Other medications provide hormones to the body when the thyroid is too damaged to produce these substances naturally.

Several types of thyroid medications are available. They include antithyroid medications, thyroid hormone, beta blockers and radioactive iodine therapy.

Antithyroid medications

These drugs treat Graves’ disease and other causes of hyperthyroidism by preventing the thyroid gland from producing excess levels of hormones. Patients typically begin to feel better within two to 12 weeks of beginning treatment. Treatment regimens often last up to a year or longer. Though these drugs are effective, they generally do not cure the condition, and some patients may experience a relapse of their condition when medication is discontinued.

The U.S. Food and Drug Administration (FDA) has approved two antithyroid drugs: methimazole (Tapezole) and propylthioracil (PTU). PTU is usually given in three equal doses eight hours apart. Tapezole can usually be taken at longer intervals between doses

Thyroid hormone

Usually this is a synthetic version of natural thyroid hormones thyroxine (T4) and/or triiodothyronine (T3). In most cases, thyroid hormone is given to patients whose thyroid does not function efficiently enough to provide their body with the amount of hormone it requires, a condition called hypothyroidism. However, the medication is also sometimes used in an effort to suppress further growth of thyroid tissue to treat conditions such as thyroid nodules, although there is some controversy about the effectiveness of this therapy.

Brands of synthetic thyroid hormone may include additional ingredients that differ from other versions. These medications include:

• levothyroxine (L-Thyroxin, Levolet, Levo-T, Levothroid, Levoxyl, Novothyrox, Synthroid, Thyro-Tabs, Unithroid)
• liothyronine (Cytomel)
• liotrix (Euthroid, Thyrolar)

Synthetic thyroid hormones are typically taken as daily tablets, but some are available as injections to treat conditions such as myxedema coma, a rare but life-threatening complication of severe hypothyroidism.

Concerned that thyroxine generics might not be equivalent to branded drugs, the American Association of Clinical Endocrinologists, the American Thyroid Association and The Endocrine Society recommend staying with one preparation and avoiding substitutions.

There are also natural hormonal preparations made from desiccated (dried) pig thyroid glands, such as Armour Thyroid tablets. The FDA states that synthetic thyroid hormone is identical to natural thyroid hormone, which has fallen out of favor with some physicians and is not always readily available. However, many individuals with hypothyroidism have found that the natural hormonal drug is better at reducing symptoms of thyroid hormone deficiency for them, and for this reason some physicians prefer it.

Thyroglobulin, also derived from pigs, is no longer available in the United States.

The FDA warns against using thyroid hormone in an attempt to treat obesity in people with normal thyroid function. High doses may cause serious or even life-threatening toxicity, especially if combined with amphetamine diet pills. The agency has also warned in the past against purported weight-loss supplements that actually contain strong thyroid hormones which could cause heart attack, stroke or other serious conditions.

In addition, thyroid hormone should not be used in an attempt to treat female or male infertility that is not accompanied by hypothyroidism, the FDA advises.

Beta blockers

These antihypertensives are primarily prescribed for cardiovascular conditions including high blood pressure, arrhythmias, angina, heart attack and heart failure. However, they are also prescribed for other conditions such as glaucoma and migraines, and are effective in treating symptoms associated with hyperthyroidism, including rapid heart rate, trembling, anxiety and excessive body heat.

Patients should inform the physician if they have low blood pressure, prediabetes or diabetes, or if they are already taking an antihypertensive.

Examples of beta blockers include:

• acebutolol (Sectral)
• atenolol (Tenormin)
• betaxolol (Kerlone)
• bisoprolol (Zebeta)
• carteolol (Cartrol)
• carvedilol (Coreg)
• labetalol (Normodyne, Trandate)
• metoprolol (Lopressor, Toprol-XL)
• nadolol (Corgard)
• nebivolol (Bystolic)
• penbutolol (Levatol)
• pindolol (Visken)
• propranolol (Inderal)
• sotalol (Betapace)
• timolol (Blocadren)

Radioactive iodine

Normally, the thyroid pulls the element iodine out of a person’s bloodstream so that it can be used to make hormones. When iodine that has been rendered radioactive is taken in liquid or pill form, the thyroid collects the iodine and, in treatment doses, the radioactivity destroys the gland. Typically, this treatment takes between six and 36 weeks to achieve its effect. A large percentage of people who receive this therapy will develop hypothyroidism and need to take thyroid hormone for the rest of their lives.

It is important that patients take thyroid medications exactly as prescribed by a physician. This helps ensure that treatment regimens are effective and safe. For example, patients who take one brand of thyroid hormone should not take another brand without a physician’s approval. The various brands of thyroid hormone contain different ingredients and can affect patients in different ways.

Thyroid patients may also be prescribed other medications to treat various complications. For example, people with Graves’ disease who develop Graves’ ophthalmopathy may be prescribed corticosteroids or lubricating eye drops, and those who Graves’ dermopathy may be treated with hydrocortisone skin creams.