Overactive thyroid (hyperthyroidism)

An overactive thyroid is where the thyroid gland produces too much of the thyroid hormones. The thyroid is found at the front of the neck. An overactive thyroid can affect anyone. It is more common in women than men. The number of people affected by the condition increases with age.

Symptoms of an overactive thyroid 

The thyroid produces hormones that affect things such as:

  • growth
  • development
  • metabolism (converts fuel in food to energy needed by the body)

The hormones can also affect your heart rate and body temperature.

An overactive thyroid (hyperthyroidism) can cause a wide range of possible symptoms. It's unlikely you'll experience all of them.

The symptoms may develop gradually or suddenly. For some people they're quite mild. For others, they can be severe and significantly affect their life.

Common symptoms 

Symptoms of an overactive thyroid can include:

  • nervousness, anxiety and irritability
  • hyperactivity – you may find it hard to stay still and feel full of nervous energy
  • mood swings
  • difficulty sleeping
  • exercise intolerance, fatigue, muscle weakness
  • sensitivity to heat
  • increased appetite with weight loss (or occasionally weight gain)
  • diarrhoea
  • needing to pee more often than usual
  • persistent thirst
  • itchiness
  • loss of interest in sex 
  • difficulty in controlling blood glucose in people with diabetes
  • difficulty in swallowing if the thyroid gland is enlarged

Older people may present with few symptoms or other symptoms, such as deterioration of pre-existing heart disease, depression, or anorexia, which may make the diagnosis more difficult.

Common signs 

An overactive thyroid can also cause the following physical signs including:

  • a swelling in your neck caused by an enlarged thyroid gland (goitre)
  • an irregular and/or unusually fast heart rate (palpitations)
  • twitching or tremor
  • warm skin and sweating a lot
  • red palms of your hands
  • loose nails
  • a raised, itchy rash – known as hives (urticaria)
  • patchy hair loss or thinning
  • weight loss – often despite an increased appetite
  • eyes open more than normal giving a startled appearance
  • eye problems, such as redness, dryness or vision problems 
  • ankle swelling
  • wasting of your muscles
  • gynaecomastia - development of breast tissue in men

When to see your GP 

See your GP if you have symptoms of an overactive thyroid.

They will ask about your symptoms. They can also arrange a blood test if they think you might have a thyroid problem. This is to check the hormone levels to see how well your thyroid is working.

If the blood test shows that you have an overactive thyroid, you may be referred for further tests to identify the cause.

Treatments for an overactive thyroid 

An overactive thyroid is usually treatable.

The main treatments are:

  • medication that stops your thyroid producing too much of the thyroid hormones
  • radioiodine treatment – where radiation is used to damage your thyroid, reducing its ability to produce thyroid hormones
  • surgery to remove some or all of your thyroid, so that it no longer produces thyroid hormones

Each of these treatments has benefits and drawbacks. You'll normally see an endocrinologist (specialist in hormone conditions) to discuss which is best for you.

Causes of an overactive thyroid 

There are a number of reasons why the thyroid can become overactive.

These include:

  • Graves' disease – where the body's immune system mistakenly attacks and damages the thyroid
  • lumps (nodules) on the thyroid – this results in extra thyroid tissue, which can mean extra thyroid hormones are produced
  • certain medications

Graves’ disease 

About three in every four cases of overactive thyroid are because of Graves' disease.

Graves’ disease is an autoimmune condition. This means the immune system mistakenly attacks a part of the body - in this case the thyroid gland. The damaged thyroid gland becomes overactive (producing too much of the thyroid hormones).

The cause of Graves' disease is unknown. It mostly affects young or middle-aged women and it often runs in families. Smoking can also increase your risk of getting it.

Further issues  

An overactive thyroid, particularly if it's not treated or well controlled, can sometimes lead to further problems.

These include:


The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed January 2018

This page is due for review January 2020

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