Thyroid medications are drugs used to control symptoms of thyroid diseases. Several types are available, including:

• Antithyroid medications. Drugs that prevent the thyroid gland from producing excess hormones, used to treat hyperthyroidism and some thyroid nodules and tumors.
  
  
• Thyroid hormone. Synthetic or natural thyroid hormones, used mainly to treat hypothyroidism.
  
  
• Beta blockers. Antihypertensives prescribed primarily for high blood pressure and heart conditions. They also are effective in treating symptoms of hyperthyroidism.
  
  
• Radioactive iodine therapy. A treatment that destroys the thyroid gland, used to treat some cases of hyperthyroidism, thyroid nodules and thyroid cancer.

Side effects vary depending on the type of drug. Certain drugs may interact poorly when taken with thyroid medications. Patients are urged to take their medication as directed and consult their physician before taking any additional drugs or supplements.

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.

Antithyroid medications are prescribed to treat symptoms associated with a variety of thyroid conditions, including:

• Hyperthyroidism. Results from overactivity of the thyroid gland, which secretes hormones that regulate a person’s metabolism (the physical and chemical processes necessary for the maintenance of life). Patients experience the release of too much thyroid hormone into the bloodstream, causing processes in the body to speed up. Symptoms can include thyroid enlargement (goiter), rapid heart rate and sudden, unexplained weight loss.
  
  The most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder. Some people with Graves’ disease may experience variations that affect the eyes (Graves’ ophthalmopathy) or the skin on the shins and the top of the feet (Graves’ dermopathy).
  
  
• Thyroid nodules and tumors. Growth of tissue in the thyroid that is usually benign (noncancerous). Rarely are malignant (cancerous) nodules associated with hyperthyroidism.
  
  
• Thyroiditis. Inflammation of the thyroid gland. There are several types that may cause either hyperthyroidism or hypothyroidism. Although “subacute” thyroiditis can cause hyperthyroidism, in general neither propylthiouracil or methimazole is used to treat this type of condition. On the other hand, Hashimoto’s thyroiditis is a common cause of hypothyroidism.

Thyroid hormone medications are used primarily to treat hypothyroidism.

Radioactive iodine therapy may be used to treat hyperthyroidism, thyroid cancer, goiter and thyroid nodules.

The many uses of beta blockers include relieving symptoms of hyperthyroidism such as rapid heartbeat, tremors and anxiety.

Patients are urged to report any allergies to their physician. It is especially important that patients report allergies to pork if they are considering taking desiccated pig thyroid (natural thyroid hormone).

Other conditions that may affect a patient’s ability to take thyroid medications include:

• Arrhythmias (abnormal heart rhythms), atherosclerosis or other cardiovascular disease
  
  
• Diabetes
  
  
• Certain other endocrine diseases, such as unresolved Addison’s disease (adrenal insufficiency) or an underactive pituitary gland (hypopituitarism)
  
  
• Kidney disease, such as proteinuria, diabetic nephropathy or end-stage renal disease
  

  

• Liver disease
  
  
• Malabsorption diseases (e.g., celiac disease, lactose intolerance, cystic fibrosis, Whipple disease)
  
  
• Osteoporosis

Side effects associated with thyroid medications vary depending on the type of drug the patient is taking.

About 5 percent of patients may have an allergic reaction to antithyroid medications, according to the American Association of Clinical Endocrinologists. Symptoms include yellow skin (jaundice), skin rash, hives, fever and joint pain. This is most likely to occur within the first six weeks of treatment and usually subsides within a couple of weeks after a patient stops using the medication.

Uncommonly, antithyroid medications can damage neutrophils, a type of white blood cell that helps eradicate bacteria. Patients who use these drugs and develop a sore throat, fever or other signs of infection are urged to seek immediate medical attention so they can have a blood test performed. This should be done before the patient takes the next dose of antithyroid medication.

Thyroid drugs are among the medications that can in rare cases cause drug-induced lupus. Symptoms can include muscle and joint pain and swelling, fatigue, fever and painful inflammation around the lungs or heart. Drug-induced lupus typically resolves when the medication is discontinued. It is far less serious than systemic lupus erythematosus, a chronic autoimmune disorder.

Patients who take too much thyroid hormone may develop hyperthyroidism or other side effects, such as strain on the heart or osteoporosis. Patients who take too little are likely to experience continued hypothyroidism. In addition, patients who take thyroid hormone to try to suppress the growth of thyroid nodules or enlarged thyroid gland (goiter) may experience several side effects. These include irregular or fast heartbeat, chest pain and decreased bone density.

Radioactive iodine therapy initially causes a release of thyroid hormone into the bloodstream that may cause symptoms to worsen for a time after treatments begin. These symptoms may include neck tenderness, sore throat and signs of hyperthyroidism. However, over time they begin to reverse as the treatment takes effect.

Beta blockers can cause mild hyperglycemia in diabetic patients, and studies have found them to be a minor risk factor for diabetes. Depending on the type of beta blocker prescribed, patients may experience various side effects, such as slow heart rate (bradycardia), shortness of breath (dyspnea) or wheezing, dizziness or fainting.

Other side effects associated with thyroid medications can include:

• Anxiety
• Burning, tingling or other abnormal sensations
• Diarrhea, stomach cramps or other gastrointestinal upset
• Drowsiness
• Fever
• Flushing
• Hair loss
• Headache
• Hyperactivity
• Increased appetite (polyphagia)
• Loss of taste or salty taste
• Menstrual cycle changes
• Mouth sores or throat infection
• Muscle/joint pain or weakness
• Nausea or vomiting
• Rapid changes in mood (e.g., irritability)
• Skin rash, itchiness or eruptions
• Sleeping difficulties
• Swelling (edema)
• Tremor or shakiness
• Weight changes

Certain drugs may interact poorly when taken with thyroid medications. Patients are urged to consult their physician before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

Certain medications can alter the amount of thyroid hormone that a patient requires for the hormone to be effective. Such medications include birth control pills, estrogen, testosterone or other androgens, anticonvulsants (seizure medications), antidepressants and cholesterol drugs.

Other drugs that may interact with thyroid medications include:

• Anticoagulants (drugs that hinder blood clotting)
• Antihypertensives
• Antidiabetic agents
• Aspirin and other salicylates
• Oral corticosteroids
• Some heart drugs (e.g., digoxin)
• Some HIV drugs (e.g., efavirenz)
• Human growth hormone
• Insulin

Symptoms of overdose can be similar to the medication’s side effects but are usually more severe. Patients exhibiting any of these symptoms should contact their physician immediately:

• Breathing difficulties
  
• Changes in menstrual periods
  
• Coldness
  
• Constipation
  
• Dry, puffy skin
  
• Headache
  
• Listlessness or sleepiness
  
• Muscle aches
  
• Rapid or irregular heartbeat
  
• Seizures
  
• Swelling in the front of the neck
  
• Unusual fatigue or weakness
  
• Weight changes

Women who are pregnant or breastfeeding should talk to their physician about whether or not to continue taking thyroid medications. Generally, it is important for women with certain thyroid conditions to continue to take thyroid hormone throughout their pregnancy. In many cases, a physician will recommend boosting dosage levels of thyroid hormone at this time, as normal thyroid function in the mother is important to a fetus’ good health.

However, pregnant women are not treated with radioactive iodine therapy. If other medications cannot be used, thyroid surgery may be recommended for pregnant patients with some forms of hyperthyroidism.

Use of beta blockers during pregnancy may cause low blood sugar (hypoglycemia), breathing problems, a slow heart rate and low blood pressure in the newborn. However, if the mother’s condition warrants the use of beta blockers during pregnancy, they can be used under her physician’s guidance.

Some thyroid medications may pose potential dangers to the offspring of women who are pregnant or breastfeeding. For this reason, women are urged to consult their physician about the risks and benefits of using these medications.

Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about thyroid medications:

1. Which thyroid medication do you suggest for my condition? Why?
   
   
2. What are the alternative treatments available to me?
   
   
3. What are the side effects and risks associated with this drug?
   
   
4. What are the risks if I do not begin treatment?
   
   
5. Will I have to stop taking other medications while I am on this drug?
   
   
6. How soon after I start taking this drug should I begin to notice improvement?
   
   
7. For how long will I be required to take this medication?
   
   
8. What should I do if I miss a dose of my drug or take too much?
   
   
9. If the drug is not effective for me, is there another thyroid medication I should try?
   
   
10. Is this drug safe for me if I’m pregnant or breastfeeding?
    
    
11. Is this drug safe for my child or elderly parent?