Overactive Thyroid Medication

After an overactive thyroid diagnosis, your doctor will prescribe a treatment plan. You may need to take medication to alleviate your symptoms and put your thyroid hormones back at normal levels. 

What does your thyroid do?

Your thyroid is a butterfly-shaped gland located in the front of your neck. This gland produces two vital hormones, thyroxine (T4) and triiodothyronine (T3). These hormones help control how your body uses energy. 

What is an overactive thyroid?

You have an overactive thyroid — also called hyperthyroidism — if your body produces too much T4 and T3. This hormone imbalance affects almost every organ in your body. Someone with an overactive thyroid can experience unexplained weight loss, heat intolerance, increased sweating, irregular or rapid heartbeat, and menstrual cycle changes.

Graves' disease causes about 80% of all hyperthyroidism cases in the US.¹ This autoimmune disorder causes your immune system to mistakenly attack your thyroid gland.

An overactive thyroid is not contagious. You can't catch the condition from anyone or give it to someone else. You have an increased risk for hyperthyroidism if you have a close blood relative with a thyroid condition. 

What are common thyroid medication treatment options? 

Anti-thyroid drugs and beta-blockers are used to treat hyperthyroidism and its associated symptoms. All of these drugs require a prescription from your healthcare provider.

Antithyroid medications

Propylthiouracil and methimazole are two antithyroid drugs commonly prescribed to treat an overactive thyroid. These medications cause the thyroid to produce fewer T4 and T3 hormones.

Beta-blockers

Beta-blockers don't directly treat an overactive thyroid, but these drugs can reduce certain symptoms. Some people experience almost immediate relief from tremors and a rapid heartbeat.

Do overactive thyroid medications have side effects?

All medications have the potential to cause side effects. If your doctor prescribes a hyperthyroidism drug, they feel the benefits outweigh your risks. Call your healthcare provider right away if you experience any unusual symptoms while taking medication for an overactive thyroid.

Propylthiouracil side effects

Propylthiouracil can cause severe liver damage. If you cannot tolerate methimazole or other hyperthyroidism treatments like surgery or radioactive iodine, your doctor may prescribe this drug. If you're pregnant, your doctor may also prescribe propylthiouracil during your first trimester, as methimazole may cause congenital disorders when taken during early pregnancy.

You should call your doctor right away if you experience itching, dark or foamy urine, stools that are lighter than normal, your eyes or skin appear yellow, or you develop pain in the upper right side of your stomach while taking propylthiouracil.

Other side effects of propylthiouracil include hair loss, a diminished sense of taste, unusual sensations in your hands or feet like numbness or tingling, unexplained pain in your joints or muscles, dizziness, and swelling in your neck.

Methimazole side effects

Methimazole can cause an upset stomach, vomiting, and a decreased sense of taste. You may experience skin changes such as a rash, itching, or tingling sensations. Taking methimazole can also make you feel dizzy or tired, cause swelling or muscle and joint pain, and decrease your white blood cells and platelets.

Agranulocytosis

Overactive thyroid medications can cause an extremely rare but serious condition called agranulocytosis. The most common symptoms of agranulocytosis are a high fever and sore throat. The condition can also cause mouth sores, a cough, and chills.

Approximately 0.2–0.5% of patients with Graves' disease² who take hyperthyroid medication will develop the condition. If you experience these symptoms while taking an anti-thyroid medication, see a doctor right away.

This is not a comprehensive list of medication side effects. Please talk to your doctor if you have any questions about your overactive thyroid medication. 

How effective are overactive thyroid medications long-term? 

You may have to take antithyroid medication for several weeks or months before your levels of T3 and T4 become normal. During that time, your healthcare provider may ask you to come in for periodic lab work to check your hormone levels.

The long-term effectiveness of antithyroid medications depends on your age, the underlying cause of your hyperthyroidism, and other factors. Your doctor may recommend taking propylthiouracil or methimazole in conjunction with another overactive thyroid treatment.

How long does hyperthyroidism treatment last? 

The average hyperthyroidism treatment time³ is one to two years. However, your doctor will tailor a treatment plan specific to you and the cause of your hyperthyroidism. 

What other interventions are available for an overactive thyroid? 

In addition to overactive thyroid medications, your doctor may recommend radioactive iodine treatment or thyroid surgery.

Radioactive iodine 

Radioactive iodine is the most common treatment for Graves' disease in the US.⁴ Taken orally as a capsule or liquid, it targets the thyroid gland and destroys the hormone-producing cells without harming other body parts.

Surgery

For some patients with hyperthyroidism, surgery to remove all or part of the thyroid is the best option.

Many patients who have radioactive iodine treatment or thyroid surgery will develop hypothyroidism. If you have this condition, your body doesn't produce enough T3 and T4 hormones. Hypothyroidism is easier to treat than hyperthyroidism, as it can be controlled with a daily medication like Armour Thyroid and levothyroxine.

When to speak to a healthcare professional/endocrinologist

You should see a healthcare provider if you experience any symptoms of liver damage or agranulocytosis. You should also let your doctor know if your hyperthyroid symptoms don't go away or get better and return.

Some hyperthyroid medications and treatments are unsafe for pregnant women and pose a risk to the fetus. If you become pregnant while taking thyroid medication, let your doctor know right away. You may need to switch treatments or medication during your pregnancy. If you plan to become pregnant, talk with your doctor about what hyperthyroid treatments are an option for you.

The lowdown

Propylthiouracil and methimazole are the two most commonly prescribed medications for overactive thyroid. In rare cases, antithyroid drugs can cause a condition called agranulocytosis. Know the symptoms of agranulocytosis and when to call your doctor. Your doctor may also prescribe a beta-blocker to reduce your hyperthyroid symptoms. Some medications are unsafe for pregnant women. Let your healthcare provider know if you are pregnant or plan to become pregnant.