Hyperthyroidism (Overactive Thyroid)

Medically Reviewed by Brunilda Nazario, MD on January 19, 2021

Hyperthyroidism is when your thyroid -- the butterfly-shaped gland at the bottom of your neck, just above your collarbone -- makes too much of a hormone called thyroxine.

Your thyroid controls things like how fast your heart beats and how quickly you burn calories. It releases hormones to control your metabolism (all the things your body does to turn food into energy and keep you going).

Hyperthyroidism, also known as overactive thyroid, can speed up your metabolism and cause unpleasant symptoms.

Hyperthyroidism Signs and Symptoms

Common signs include:

If you’re an older adult, you’re more likely to have subtle symptoms like a faster heart rate or being more sensitive to warm temperatures. Or you could just feel more tired after everyday activities.

Certain medicines can mask the signs of hyperthyroidism. If you take beta-blockers to treat high blood pressure or another condition, you might not know you have it. Be sure your doctor knows about all the medications you take.

When you first get hyperthyroidism, you may feel energetic. This is because your metabolism is sped up. But over time, this increase in your metabolism can break your body down and cause you to feel tired.

Usually, hyperthyroidism develops slowly. If you’re young when you get it, the symptoms might come on suddenly.

Hyperthyroidism Causes

Several conditions can cause hyperthyroidism.

  • Graves’ disease. This immune system disorder is the most common cause of hyperthyroidism. It’s more likely to affect women under the age of 40.
  • Thyroid nodules. These lumps of tissue in your thyroid can become overactive, creating too much thyroid hormone.
  • Thyroiditis. An infection or an immune system problem can cause your thyroid to swell and leak hormones. This is often followed by hypothyroidism, in which your thyroid doesn’t make enough hormones. These conditions are usually temporary.

You can also get hyperthyroidism if you get lots of iodine in your diet (like in a medication or supplement) or from taking too much thyroid hormone medication.

Thyroid Eye Disease

About 30% of people with Graves’ disease get a condition called thyroid eye disease. It involves your vision and eyes, including the muscles and tissues around them. Symptoms include:

  • Bulging eyes 
  • A gritty feeling, pain, or pressure in your eyes
  • Redness or inflammation in or around your eyes
  • Eyelids that are puffy or pulled back
  • Sensitivity to light
  • Double vision or loss of vision

People with Graves’ disease may also get a rare condition called Graves’ dermopathy. It can cause redness and thickening of your skin, usually on the tops of your feet or your shins.

Hyperthyroidism Diagnosis

Your doctor will ask about your medical history and look for symptoms including a swollen thyroid, a fast pulse, moist skin, and shaking in your hands or fingers. They’ll give you tests that might include:

  • Thyroid panel. This blood test measures levels of thyroid hormones and thyroid-stimulating hormone (TSH).
  • Thyroid scan. A technician injects a small amount of radioactive iodine into your bloodstream. Your thyroid absorbs it, and a special camera takes pictures of the gland to look for nodules or other signs of problems.
  • Ultrasound. A technician runs a device called a transducer over your neck. It uses sound waves to create images of your thyroid.
  • Radioactive iodine uptake test. You swallow a small amount of radioactive iodine. A device called a gamma probe measures how much of the iodine collects in your thyroid. If this uptake is high, you probably have Graves’ disease or thyroid nodules.

Hyperthyroidism Treatment

Your doctor will help you decide on a treatment based on your age, your overall health, the kind of hyperthyroidism you have, and how severe it is. Your options might include:

  • Antithyroid drugs. Methimazole (Tapazole) and propylthiouracil (PTU) block your thyroid from making too many hormones. Side effects include allergic reactions like rash or itching. It’s rare, but these drugs can also cause your body to make fewer white blood cells. This makes you more likely to get infections. Rarely, these medicines can damage your liver, so call your doctor right away if you have symptoms like yellow skin or eyes, fatigue, or pain in your belly.
  • Beta-blockers. These medications don’t treat your levels of thyroid hormone but can help with symptoms like anxiety, shaking, or a fast heartbeat.
  • Radioactive iodine. You swallow a small amount of radioactive iodine. Overactive thyroid cells absorb it, and it destroys them. This makes your thyroid shrink and your levels of thyroid hormone go down. You might need to have this treatment more than once. It may also cause hypothyroidism. This is easier to treat than hyperthyroidism: You’ll take a hormone supplement once a day. 
  • Surgery. If medications aren’t a good option for you, your doctor may remove all or part of your thyroid. This is called thyroidectomy. You might need to take antithyroid medicines before the surgery to prevent complications. Afterward, you might have hypothyroidism and need to take a hormone supplement.
WebMD Medical Reference



Mayo Clinic: “Hyperthyroidism (overactive thyroid),” “Graves' disease.”

American Thyroid Association: “Hyperthyroidism (Overactive).”

MedlinePlus: “Hyperthyroidism.”

National Institute of Diabetes and Digestive and Kidney Diseases: “Hyperthyroidism (Overactive Thyroid),” “Thyroid Tests.”

Merck Manual Consumer Version: “Hyperthyroidism (Thyrotoxicosis).”

Cleveland Clinic: “Hyperthyroidism.”

Johns Hopkins Medicine: “Hyperthyroidism.”

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