Hyperthyroidism vs. Hypothyroidism: What’s the Difference?
Thyroid DiseaseHyperthyroidism

What’s the Difference Between Hyperthyroidism and Hypothyroidism?

What’s the Difference Between Hyperthyroidism and Hypothyroidism?
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Updated on February 16, 2026
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The thyroid, a butterfly-shaped gland located in the front and at the base of your neck, acts as the metabolic control center for your body. The hormones that your thyroid secretes help maintain the brain, heart, muscles, and other organs, and help the body to use energy properly.

But when your thyroid starts dysfunctioning, you may experience one of the following thyroid conditions. Hyperthyroidism (also known as an overactive thyroid) causes your metabolism to rapidly speed up. On the other hand, hypothyroidism (also known as an underactive thyroid) causes your metabolism to slow down. Both of these conditions affect your thyroid and overall health in different ways, which is why their symptoms, causes, and treatment options also differ.

“The major difference between hypothyroidism and hyperthyroidism is the thyroid’s hormone output,” says Minisha A. Sood, MD, an endocrinologist based in New York City. With hyperthyroidism, the thyroid makes more thyroid hormone than your body needs. But with hypothyroidism, the thyroid gland doesn’t make enough, explains Dr. Sood.

Illustrative graphic titled How Thyroid Problems Affect the Body. Hypothyroidism vs hyperthroidism. Everyday Health logo.
You may experience any of these symptoms if your thyroid gland is either underactive or overactive.
The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s disease, a condition where the immune system makes antibodies that destroy thyroid cells and stop them from making the thyroid hormone.

In contrast, one of the most common form of hyperthyroidism is a condition called Graves’ disease.

 Some people with Graves’ disease have swelling in the front of their neck from an enlarged thyroid gland, called a goiter, and eyes that appear enlarged because of inflammation.

Symptoms of Hypothyroidism and Hyperthyroidism

With hypothyroidism, “your whole metabolism slows down, the heart rate is slower than normal, the intestinal tract becomes sluggish, and there is less heat production,” says Mario Skugor, MD, an endocrinologist at Cleveland Clinic who specializes in thyroid disorders.

As a result of an underactive thyroid, you may experience:

  • Fatigue
  • Forgetfulness
  • Dry skin
  • Dry hair
  • Brittle nails
  • Constipation
  • Weight gain
  • Muscle cramps
  • Depression
  • Decreased menstrual flow
  • Swelling in the front of the neck (goiter)

“The weight gain that often accompanies hypothyroidism is a funny thing,” Dr. Skugor notes. “If a person with an underactive thyroid can force him- or herself to maintain a normal activity level, he or she may only gain a few pounds,” he says. “But some people with hypothyroidism feel so tired they stop exercising, sleep more, and change their routine, which causes more weight gain.”

But with an overactive thyroid, all body functions tend to speed up. Think of it as a racing car engine. “People with hyperthyroidism will have symptoms of a fast metabolism,” Skugor says.

As a result of an overactive thyroid, you may experience:

  • Feeling hot
  • Sweating
  • Problems falling asleep
  • Racing thoughts
  • Difficulty focusing on one task
  • Forgetfulness
  • Change in bowel habits, where bowels are looser
  • Elevated heart rate and palpitations
  • Anxiety, nervousness, or irritability
  • Weight loss
  • Menstrual problems
  • Fatigue

“It’s important to note that weight loss associated with overactive thyroid is not happy weight loss,” Skugor explains. “It is associated with muscle weakness and constant fatigue, so it isn’t something you want.”

If you experience any of the above symptoms of thyroid disorders — either underactive thyroid or overactive thyroid — see your healthcare professional. They can order tests to determine whether your thyroid hormone levels are in the normal range, and if they are not, they can provide treatments to ease your symptoms.

Incidence Rates and Risk Factors of Thyroid Disorders

Hypothyroidism is much more common than hyperthyroidism. Estimates suggest that about 5 percent of people in the United States receive a diagnosis after the age of 12. Hyperthyroidism is less common, with an incidence rate of 1 in 100.

Women are more likely to get thyroid disease, and both hypothyroidism and hyperthyroidism occur more often in women over 60. About 1 in 8 women is estimated to have thyroid disease at some point during their lifetime.

Other risk factors for thyroid disease include having a family history of hypothyroidism or hyperthyroidism, undergoing radiation therapy on your head or neck, taking medications high in iodine, or living with autoimmune disorders like type 1 diabetes, lupus, or rheumatoid arthritis.

How to Diagnose Hypothyroidism vs. Hyperthyroidism

The first step in diagnosing either hypothyroidism or hyperthyroidism is a simple blood test. Your doctor will likely ask you to fast for the test for the most accurate result. This means you can’t eat any food for at least eight hours before the test.

A blood test will measure three types of thyroid hormones. The first is called the thyroid-stimulating hormone (TSH), which is released by the pituitary gland in the brain. A high TSH result, in this instance, means that your pituitary gland is in overdrive, likely trying to compensate for an underactive thyroid gland. (The pituitary gland can kick into overdrive because of other factors, though, independent of the thyroid gland.) A low result means you’re getting an abnormally high amount of thyroid hormones in the blood and may indicate hyperthyroidism.

The two other hormones your doctor may check include free-thyroxine (T4) and total triiodothyronine (T3). Your doctor may also check free T4 levels, which is a measurement of T4 before it’s stored in various tissues throughout the body. Low levels of any of these hormones indicate hypothyroidism, while high levels point to hyperthyroidism.

Subsequent diagnostic tests depend on what your doctor finds in your initial bloodwork and during a physical exam. An enlarged thyroid gland may require an ultrasound to diagnose possible thyroid nodules. But you may need a fine-needle biopsy in addition to the ultrasound. This involves taking a small sample out of the nodule to screen it for cancer.

Another way to diagnose hyperthyroidism is called a radioactive iodine uptake test, which will be used in conjunction with an ultrasound. First, the technician conducting your test will ask you to take a capsule containing radioiodine. A healthy thyroid gland takes up only the amount of iodine it needs. If images show that your thyroid takes up too much of the iodine, then you may have hyperthyroidism. On the other hand, if your thyroid isn’t taking up enough iodine, this could be a sign of hypothyroidism.

Treatment Differences Between Hypothyroidism and Hyperthyroidism

Treatment for hypothyroidism and hyperthyroidism differs. While the key to hypothyroidism treatment is to get your thyroid levels up, hyperthyroidism treatment focuses on lowering hormone levels.

 Keep in mind: This can be a hit-and-miss process at first, until your doctor figures out the right amount of medicine that you need to stabilize your thyroid.
With hypothyroidism, lifelong use of medication is often necessary.

 Levothyroxine (Synthroid) is standard in hypothyroidism treatment, as it helps replace missing thyroxine (T4) hormones in the body. While you may need occasional dosage adjustments, most people don’t outgrow taking this medication.
Hyperthyroidism treatment, on the other hand, will vary depending on several factors, including the severity of your condition, your age, and your overall physical health. Antithyroid medications like methimazole (Northyx) or propylthiouracil (Propycil) work by stopping the thyroid gland from making too many hormones. It’s important to know that these medications don’t damage the thyroid. Sometimes, you may also need beta-blockers to minimize the effects of too much thyroid hormone on the body, such as heart palpitations.

More severe cases of hyperthyroidism may require radioiodine treatments. Radioactive iodine destroys thyroid cells to decrease the release of hormones in the body. But this approach is not the gold standard and only becomes necessary if other medications aren’t working. The caveat to this treatment is that it may reverse your condition too far and can lead to hypothyroidism, for which you’ll then need to take thyroid hormone medications.

For people who want an alternative to radioiodine treatment or antithyroid medications, surgery is an option for hyperthyroidism. Surgery removes the part of the thyroid gland that is causing the underlying issues. Full surgical removal is called a thyroidectomy. A partial thyroidectomy, or hemi-thyroidectomy, means that only one side of the thyroid gland is removed. If your entire thyroid is removed, your body no longer makes any thyroid hormone, and you’ll need to take levothyroxine.

Complications, Prognosis, and Outlook for Thyroid Conditions

The overall outlook and prognosis vary between hypothyroidism and hyperthyroidism. With hypothyroidism, your thyroid hormone levels and overall symptoms may improve with medication, but it’s a condition you’ll likely be treating for the rest of your life. This is not necessarily the case with hyperthyroidism. If antithyroid medications work, then your thyroid hormone levels will normalize without any further issues.

Once you have any form of thyroid disease, though, your doctor will monitor your condition with occasional blood tests to make sure your thyroid hormones are at optimal levels.

Like with any other health condition, complications are possible. For thyroid disease, these may include:

  • Anxiety (seen more often in hyperthyroidism)
  • Depression (seen more often in hypothyroidism)
  • Weight fluctuations
  • Fertility issues
  • Birth defects
  • Heart problems
  • High blood pressure

If you notice any adverse effects of your treatment or new or worsening symptoms, it’s always a good idea to reach out to your doctor. They’re the best fit to support your treatment journey and can offer personalized health advice.

The Takeaway

  • Hypothyroidism and hyperthyroidism are both types of thyroid disease, but their symptoms, causes, risk factors, and treatment options greatly differ.
  • Symptoms of hypothyroidism often includea slower metabolism, unintended weight gain, and fatigue, while common hyperthyroidism symptoms include a rapid metabolism, excessive sweating, and difficulty sleeping.
  • The goal of treatment for hypothyroidism is to increase and stabilize your thyroid hormone levels, while the goal for treatment for hyperthyroidism is to lower your thyroid hormone output.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Thyroid. Cleveland Clinic. June 7, 2022.
  2. What’s the Difference Between Hypothyroidism and Hyperthyroidism? Cleveland Clinic. March 10, 2025.
  3. Hypothyroidism (Underactive Thyroid): Symptoms and Causes. Mayo Clinic. December 10, 2022.
  4. Hyperthyroidism (Overactive Thyroid): Symptoms and Causes. Mayo Clinic. November 30, 2022.
  5. Thyroid Disease. Office on Women’s Health. February 22, 2021.
  6. Thyroid Disease. Cleveland Clinic. March 25, 2024.
  7. Thyroid Function Tests. American Thyroid Association.
  8. Sievert D. Hypothyroidism vs. Hyperthyroidism – What’s the Difference? UCLA David Geffen School of Medicine. January 30, 2024.
  9. Thyroid Surgery. American Thyroid Association.
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Anna L. Goldman, MD

Medical Reviewer
Castle Connolly Top Doctor

Anna L. Goldman, MD, is a board-certified endocrinologist. She teaches first year medical students at Harvard Medical School and practices general endocrinology in Boston.

Dr. Goldman attended college at Wesleyan University and then completed her residency at Icahn School of Medicine at Mount Sinai Hospital in New York City, where she was also a chief resident. She moved to Boston to do her fellowship in endocrinology at Brigham and Women's Hospital. She joined the faculty after graduation and served as the associate program director for the fellowship program for a number of years.

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Kristeen Cherney, PhD

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Kristeen Cherney, PhD, is a freelance writer, essayist, author, and poet with more than 15 years of health writing experience for digital platforms such as Healthline, The Mighty, and LiveStrong. She’s covered nutrition, women’s and children’s wellness issues, as well as specialized topics ranging from diabetes and thyroid disease to anxiety, depression, asthma, allergies, and skin conditions.

With a doctorate in English (rhetoric and composition), Dr. Cherney focuses her academic scholarship on the intersection between disability and literacy. She also holds a Master of Arts in English and a Bachelor of Arts in communication.

Cherney has contributed to the books The Wiley Handbook on Violence in Education: Forms, Factors, and Preventions, Composing in Four Acts: Readings for Writers, and Georgia State University's Guide to First-Year Writing, as well as to scholarly journals like Praxis, the Journal of Teaching Writing, and the Journal of Dracula Studies.

Cherney enjoys running, meditating, hiking, and paddleboarding.
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