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Symptoms - Overactive thyroid (hyperthyroidism)

An overactive thyroid (hyperthyroidism) is where your thyroid gland produces more thyroid hormones than your body needs.

The thyroid produces hormones that affect things such as your heart rate and body temperature.

If you have too much of these hormones, it can cause serious problems that may need treatment.

Symptoms can develop gradually or suddenly. For some people they can be mild and manageable. For others they can be severe and significantly affect their lives.

Symptoms of an overactive thyroid

Symptoms of an overactive thyroid include:

  • nervousness, anxiety and irritability
  • hyperactivity - you may find it hard to stay still and feel full of nervous energy
  • mood swings
  • difficulty sleeping (insomnia)
  • feeling tired all the time
  • sensitivity to heat
  • muscle weakness
  • diarrhoea
  • needing to pee more often than usual
  • persistent thirst
  • itchiness
  • loss of interest in sex

Common signs

Your GP may check for the following signs:

  • a swelling in your neck caused by an enlarged thyroid gland (goitre)
  • an irregular or unusually fast heart rate (palpitations)
  • twitching or trembling
  • warm skin and excessive sweating
  • red palms of your hands
  • loose nails
  • a raised, itchy rash - known as hives (urticaria)
  • patchy hair loss or thinning
  • increased appetite with unintentional weight loss
  • eye problems, such as redness, dryness or vision problems

Non-urgent advice: Contact your GP if:

  • you have symptoms of an overactive thyroid

These symptoms can have many causes. Your GP can arrange a blood test to find out if you have a thyroid problem.

How an overactive thyroid is diagnosed

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: 20 December 2023
Next review due: 20 December 2026