8 Medications That Can Cause Hypothyroidism: Amiodarone, Lithium, and More

Healthcare professionals call it “drug-induced hypothyroidism.” Simply put, it’s what happens when a medication you’re taking causes your thyroid gland to be less active than it should be. Some medications directly affect your thyroid hormones. Others may affect the thyroid gland itself.

So, should you be worried that one of your medications might be making your thyroid gland less active? Below, we explore eight of the most common medications that can cause hypothyroidism. Plus what you and your healthcare team can do to manage it.

1. Hyperthyroidism medications

Hyperthyroidism is a health condition where you make too much thyroid hormone. There are a few different medications used to treat this. Examples include propylthiouracil (PTU), methimazole, radioactive iodine (or radioiodine), and potassium iodine.

As a side effect, these medications can make thyroid hormone levels drop too low. The iodine-containing medications, specifically, destroy cells that produce too much thyroid hormone so that it produces less thyroid hormone.

Antithyroid medications like PTU and methimazole work differently. They block thyroid hormones from being made. Sometimes your thyroid hormone levels can drop too low while taking these medications. If this happens, your prescriber may lower your dose. They’ll work with you to find a balance where your levels aren’t too high or too low.

2. Amiodarone

People take amiodarone (Pacerone) to make their heart beat more regularly. Hypothyroidism (or hyperthyroidism) is possible with amiodarone. But most people taking it don’t develop thyroid issues.

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There are several ways that amiodarone can affect thyroid function. For example, amiodarone contains a lot of iodine (almost 40%). Iodine is needed for normal thyroid function. But excess iodine can cause several thyroid-related issues, including hypothyroidism. This may be more likely to happen if you already have thyroid problems.

3. Lithium

Lithium (Lithobid) is used to treat bipolar disorder. Lithium can affect thyroid functioning in several different ways. For example, it can prevent thyroid hormones from being made and released in the body. This can result in hypothyroidism.

Hypothyroidism from lithium can happen as early as the first few months of treatment. It’s more likely to occur in certain people, including:

• Women who are over 50 years old

• People with a family history of hypothyroidism

• People with thyroid antibodies (immune system proteins that attack the thyroid cells and tissues)

In some cases, you might notice symptoms of low thyroid hormone while taking lithium. A few examples are fatigue, increased sensitivity to cold, and weight gain. Or there could be changes in your thyroid function tests, even if you don’t have symptoms.

4. Proleukin (aldesleukin)

Proleukin (aldesleukin) is a human-made form of an immune protein in the body called interleukin-2 (IL-2). This medication treats cancers such as skin cancer (melanoma) or kidney cancer.

Proleukin works in the immune system to activate white blood cells to fight against cancer cells. But the immune system may also attack healthy tissue, such as the thyroid gland. In early studies, a small percentage of people receiving Proleukin developed thyroiditis. This is an inflammation of the thyroid gland, which can lead to hypothyroidism.

If it occurs, hypothyroidism from Proleukin usually happens within 1 to 4 months of treatment. Your oncologist will likely check your thyroid function tests before starting Proleukin. After that, they’ll likely continue checking them periodically to see if your thyroid is affected.

5. Interferon alfa

Interferon alfa medications are used to treat conditions such as hepatitis (inflammation of the liver) and different types of cancer. These medications have been associated with  hypothyroidism. This is especially true for people who already have thyroid antibodies.

Interferon alfa medications can cause thyroiditis. They can also cause the body to make thyroid antibodies, which can lead to hypothyroidism.

6. Tyrosine kinase inhibitors

Have you heard of tyrosine kinase inhibitors (TKIs)? This class of medications is used to treat different types of cancers and leukemias. Examples include sunitinib (Sutent) and sorafenib (Nexavar). Up to 40% of people who take a TKI will develop hypothyroidism. Studies show that this can happen anywhere from a few weeks to several months after starting the medication.

7. Immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) help your immune system fight cancer tumors. Examples include nivolumab (Opdivo), pembrolizumab (Keytruda), and ipilimumab (Yervoy). With ICIs, it’s possible that your immune cells could also attack healthy cells, including thyroid cells. This can lead to hypothyroidism in some people.

In studies, anywhere from 4% to almost 14% of people taking ICIs had hypothyroidism. The risk was greatest with combination therapy (taking more than one ICI at the same time).

8. Thalidomide

Though uncommon, some people have developed hypothyroidism due to thalidomide (Thalomid) therapy. But experts don’t know exactly how it happens. Thalidomide is used to treat many different conditions, including multiple myeloma and leprosy.

How do you treat drug-induced hypothyroidism?

One way of managing drug-induced hypothyroidism is to take thyroid hormone replacement therapy. Levothyroxine (Synthroid) is one medication that can be used for this. Levothyroxine is a synthetic (lab-made) version of T4, one of the two thyroid hormones. It acts like the T4 made by your thyroid gland, helping to bring your levels back up to normal.

Another option is to stop the medication that’s causing hypothyroidism. However, many of these medications offer benefits that outweigh this risk. So it may not be practical to stop taking them just because your thyroid levels are low. In this case, your healthcare team can help determine the best course of action. Don’t stop taking your medication unless they tell you to do so.

Your healthcare team will likely check your thyroid function if you’re taking one of the medications listed above. How often it’s checked may depend on the medication. But you should tell your prescriber if you notice symptoms of hypothyroidism after starting treatment. Examples include fatigue, weight gain, and increased sensitivity to cold.

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Written by:

Megan N. Freeland, PharmD, RPh

Megan began her career as a public health pharmacist and transitioned into healthcare copywriting and content marketing as the CEO of StockRose Creative, LLC. As a public health pharmacist, Megan supported the Centers for Disease Control and Prevention (CDC) in medication safety, health communications, and regulatory affairs. After receiving her Bachelor of Arts in Spanish from Emory University and her doctorate degree in pharmacy from Mercer University, she completed fellowship training in drug information and health communications.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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