Revised 2018

Hyperthyroidism is a condition where the thyroid gland produces more thyroid hormones than are needed by the body. It is also known as an over-active thyroid or thyrotoxicosis.

  • Hyper - means “over -“
  • Hypo - means “under -“


  • Graves’ disease - the most common cause
  • A toxic multi-nodular goitre (a goitre is an enlarged thyroid gland)
  • A solitary toxic thyroid adenoma (an adenoma is a clump of cells)
  • Thyroiditis (or inflammation of the thyroid gland) which is temporary

Common Symptoms

A speeding up of mental and physical processes of the whole body, such as

  • weight loss, despite an increased appetite, although in a few cases patients may gain weight
  • palpitations / rapid pulse
  • sweating and heat intolerance
  • tiredness and weak muscles
  • nervousness, irritability and shakiness
  • mood swings or aggressive behaviour
  • looseness of the bowels
  • warm, moist hands
  • thirst
  • passing larger than usual amounts of urine
  • itchiness
  • an enlarged thyroid gland

If the cause is Graves’ disease, you may also have thyroid eye disease, where the eyes may become prominent and feel gritty and sore. Smokers are up to eight times more likely to develop thyroid eye disease than non-smokers.


  • By a physical examination and blood tests
  • A low thyroid stimulating hormone (TSH) level with a high thyroxine (T4) level indicate hyperthyroidism

Treatment Options


Blood tests are carried out

  • every two to six months when you first start taking antithyroid drugs and every six to twelve months during long-term treatment with antithyroid drugs
  • frequently after radioactive iodine and surgery until stable, and once a year after that

Thyroid problems often run in families and if family members are unwell they should be encouraged to discuss with their own GP whether thyroid testing is warranted.

This Quick Guide is one in a series about thyroid disorders. All Quick Guides are available on the British Thyroid Foundation website. A leaflet containing more detailed information about Hyperthyroidism is also available.

The British Thyroid Foundation
tel: 01423 810093
The British Thyroid Foundation is a registered charity: England and Wales No 1006391, Scotland SC046037

Membership Information
Quick Guides

Endorsed by:

The British Thyroid Association - medical professionals encouraging the highest standards in patient care and research

The British Association of Endocrine and Thyroid Surgeons - the representative body of British surgeons who have a specialist interest in surgery of the endocrine glands (thyroid, parathyroid and adrenal)

First issued: 2008
Revised: 2010, 2011, 2015, 2018
Our literature is reviewed every two years and revised if necessary.

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