Anti-thyroid Drugs for Graves’ Disease

If you are one of the many people with both thyroid eye disease (TED) and Graves’ disease, you are not alone. Up to 5 in 10 people with Graves’ disease develop TED. Treatments for both diseases are different, since they are separate conditions.¹

Treatment for Graves’ disease often includes anti-thyroid drugs. These drugs help reduce the effects of an overactive thyroid. Knowing the basics of Graves’ disease and its treatments can help you better manage both conditions.²

What is Graves’ disease?

Graves' disease is an autoimmune illness that affects 1 in every 200 people in the United States. Autoimmune diseases happen when the body cannot tell when things are harmful. The body gets the wrong idea and attacks healthy cells too. This can result in the damage or death of the affected healthy cells and tissue. Graves’ disease is the most common cause of overactive thyroid (hyperthyroidism).^3,4

In Graves' disease, the immune system mistakenly attacks the thyroid gland. This causes more thyroid hormones to be made. An overactive thyroid is caused by too much thyroid hormone.^3,4

TED affects up to half of those with Graves' disease. Despite their similarities, thyroid eye disease and Graves' disease are distinct diseases with different therapies.⁵

Anti-thyroid drugs are most often used to treat Graves' disease.²

Types of anti-thyroid drugs

As of January 2022, there are 2 anti-thyroid drugs approved by the U.S. Food and Drug Administration (FDA) for treating Graves’ disease:²

• Methimazole (TapazoleⓇ)
• Propylthiouracil

Methimazole (Tapazole)

Methimazole (Tapazole) helps lower thyroxine (T4) levels in the body after about 6 weeks. Your doctor may instruct you to use methimazole 3 times daily at first. Eventually, this drug is taken once daily to manage hyperthyroidism.^2,6

Propylthiouracil

Propylthiouracil does not reverse hyperthyroidism as quickly as methimazole. Also, propylthiouracil may cause liver damage in some people. This drug is taken 2 to 3 times per day.²

Methimazole is usually a better option than propylthiouracil because it reverses hyperthyroidism faster and has fewer side effects.²

Side effects of anti-thyroid drugs

Fortunately, anti-thyroid drugs are well tolerated in most people. Minor side effects of both methimazole and propylthiouracil include:^2,6

• Itching
• Rash
• Hives
• Joint pain and swelling
• Fever
• Changes in how food tastes
• Upset stomach and throwing up (nausea and vomiting)

Propylthiouracil carries an increased risk of liver damage, which often occurs in the first 3 months of treatment. Symptoms of liver damage include:²

• Yellowing of the skin and white of the eyes
• Dark urine
• Light-colored stools
• Belly pain
• Reduced appetite

These are not all the possible side effects of anti-thyroid drugs. Talk to your doctor about what to expect when taking these drugs. You also should call your doctor if you have any changes that concern you when taking anti-thyroid drugs.

Things to know about anti-thyroid drugs

You might start feeling better within a few weeks to a few months, but you will need to take anti-thyroid drugs for at least a year, sometimes longer.²

Both drugs can cause severe liver damage, sometimes leading to death. Because propylthiouracil has caused far more liver damage cases, it should generally be used only when you cannot tolerate methimazole.^2,7

Your blood will be checked during treatment to see how you are doing. Different thyroid function and hormone levels will help your doctor see if the treatment is working.²

About 1 in 3 people who take anti-thyroid drugs for 1 to 2 years will have Graves' disease symptoms go away. This is known as prolonged remission. Doctors do not know if the drugs cause this or if the lowered hormone levels help the body resolve Graves' disease on its own.²

Do anti-thyroid drugs also help TED?

Many people with TED also have Graves’ disease. Because of this, you may think that anti-thyroid drugs might help the symptoms of TED. However, Graves’ disease and TED are separate diseases and require different treatments.^1,5

If you take anti-thyroid drugs for Graves’, it is possible that your thyroid eye disease symptoms may start to lessen. However, this is not always the case, and every person is different. Seeing a TED specialist is essential to get the treatment you need to best treat your TED symptoms, regardless of whether or not you have Graves’ disease.^1,2