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Symptoms - Underactive thyroid (hypothyroidism)

An underactive thyroid is where your thyroid gland does not produce enough hormones. It is also known as hypothyroidism.

Both men and women can have an underactive thyroid. But it's more common in women.

Children can also develop an underactive thyroid. Some babies are born with it. If it is found at birth, it is called congenital hypothyroidism.

All babies born in Ireland are screened for congenital hypothyroidism using a blood spot test. This is done when the baby is around 5 days old.

Common symptoms of an underactive thyroid

Common signs of an underactive thyroid are:

  • tiredness
  • weight gain
  • feeling depressed

Many symptoms are the same as those of other conditions. Some people can confuse it for something else.

Symptoms usually develop over time. You may not realise you have a medical problem for years.

Other symptoms include:

  • being sensitive to cold
  • constipation
  • slow movements and thoughts
  • muscle aches and weakness
  • muscle cramps
  • dry and scaly skin
  • hair and nails that break easily
  • loss of libido (sex drive)
  • pain, numbness and a tingling sensation in the hand and fingers - this is known as carpal tunnel syndrome
  • irregular periods or heavy periods

If you have any of these symptoms, see your GP. Ask them to test for an underactive thyroid.

Getting tested for an underactive thyroid

If you are elderly

Elderly people with an underactive thyroid may develop memory problems and depression.

If you are a child

Children may grow and develop slower. Teenagers may start puberty early.

Symptoms of an untreated underactive thyroid

If an underactive thyroid is not treated, more symptoms can develop. But most people get treatment before serious symptoms appear.

Later symptoms include:

  • a low-pitched and hoarse voice
  • a puffy-looking face
  • thinned or partly missing eyebrows
  • a slow heart rate
  • hearing loss
  • anaemia

The thyroid gland

The thyroid gland is a small butterfly-shaped gland in the neck, just in front of the windpipe (trachea).

One of its main functions is to produce hormones that help regulate the body's metabolism. These hormones are called triiodothyronine (T3) and thyroxine (T4).

Many of the body's functions slow down when the thyroid does not produce enough of these hormones.

Find out more about an underactive thyroid

Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 25 March 2021
Next review due: 25 March 2024