Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content


6-minute read

Key facts

  • Hypothyroidism (underactive thyroid) occurs when the thyroid gland does not make enough thyroid hormone.
  • Symptoms vary, but can include fatigue, weight gain, heavy periods or sensitivity to the cold.
  • The most common cause of hypothyroidism in Australia is the autoimmune disease, Hashimoto's disease.
  • Your doctor will diagnose hypothyroidism after referring you for a blood test.
  • Hypothyroidism is often treated with a synthetic version of the hormone thyroxine.

What is hypothyroidism (underactive thyroid)?

Hypothyroidism (underactive thyroid) is a medical condition where the thyroid gland does not make enough thyroid hormone for normal body function.

The thyroid gland is located in the neck, near the base of the throat. It makes hormones that help control some of your body’s metabolic processes, such as heart rate, blood pressure, body temperature and weight.

While some people have underactive thyroids, others have overactive thyroids (hyperthyroidism). This condition has different causes, symptoms and treatments.

What are the symptoms of hypothyroidism (underactive thyroid)?

Hypothyroidism (underactive thyroid) can develop over many years without showing any symptoms. When symptoms do appear, they may vary from person to person.

Some symptoms affect your appearance, for example:

  • weight gain
  • puffy and pale face
  • brittle hair and nails, thinning hair
  • dry, cool skin

Other symptoms affect how you feel, for example:

Symptoms may also affect how you think, for example, hypothyroidism can also affect your:

Some people can have symptoms of hypothyroidism without any abnormality in their hormone levels. These symptoms may have different causes other than hypothyroidism.

If you are concerned about any of these symptoms, see your doctor.

What causes hypothyroidism (underactive thyroid)?

The most common cause of hypothyroidism in Australia is Hashimoto's disease, or thyroiditis. This is an autoimmune disease that occurs when the body’s immune cells attack the thyroid gland.

Other common causes of hypothyroidism include:

Hypothyroidism can also be a result of too little iodine in the diet, or a problem with the pituitary gland, or occasionally, pregnancy.

How is hypothyroidism (underactive thyroid) diagnosed?

Your doctor will examine your neck to check if your thyroid is enlarged or has nodules (lumps). They will also look for other signs of hypothyroidism (underactive thyroid), such as a slow heart rate.

To diagnose hypothyroidism, your doctor will order a blood test to measure your level of thyroid hormones.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

How is hypothyroidism (underactive thyroid) treated?

If you are diagnosed with hypothyroidism (underactive thyroid), you will most likely be treated with a medicine to replace the thyroid hormone. This medicine is a synthetic (artificial) version of the hormone thyroxine. In most cases, you will need to take it for the rest of your life.

Once you have started treatment, you may need to have your hormone levels checked regularly so your doctor can adjust your dose. It can take some time to find the right dose of medicine for you.

What are the complications of hypothyroidism?

If untreated, hypothyroidism can lead to a range of health problems including:

Children and teenagers with untreated hypothyroidism can have abnormal growth and development.

If you are pregnant, untreated hypothyroidism increases your risk of miscarriage and other pregnancy complications.

How is hypothyroidism prevented?

Most types of hypothyroidism can’t be prevented, but the symptoms can be managed.

You can prevent hypothyroidism caused by iodine deficiency by ensuring you include iodine in your diet. An easy way to do this is by cooking with iodised salt, and using iodised table salt. These are available at supermarkets.

If your hypothyroidism is caused by a medicine, speak to your doctor about changing it. Don’t stop any medicines without checking first with your doctor.

If you are planning a pregnancy, you should take an iodine supplement daily.

Resources and support

The Australian Thyroid Foundation offers further information on definitions, causes, conditions and treatments, as well as questions to ask your doctor.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: October 2022

Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Hypothyroidism - Hormones Australia

Hypothyroidism is the most common thyroid disorder in Australia, affecting around 1 in 33 Australians. It is usually a permanent condition where the thyroid

Read more on Hormones Australia website

Hypothyroidism (underactive thyroid)

Hypothyroidism is a lifelong condition where your thyroid gland doesn’t make enough thyroid hormones.

Read more on WA Health website

RACGP - Managing your subclinical hypothyroidism

Reproduced with permission from The Royal Australian College of General Practitioners

Read more on RACGP - The Royal Australian College of General Practitioners website

Thyroid gland and thyroid hormones -

Your thyroid gland makes hormones that control your metabolism. An overactive or underactive thyroid can cause symptoms.

Read more on myDr website

Thyroid disease in children -

Learn about the signs, symptoms and treatment of thyroid disease in children.

Read more on myDr website

Thyroid - Hashimoto's disease - Better Health Channel

Hashimoto's disease progresses very slowly over many years, so the symptoms may go unnoticed.

Read more on Better Health Channel website

RACGP - Patient resources

Reproduced with permission from The Royal Australian College of General Practitioners

Read more on RACGP - The Royal Australian College of General Practitioners website

The thyroid gland

Information on the thyroid gland and its function in regulating your body’s metabolism.

Read more on WA Health website

Thyroid Conditions and Bone Health

Bone is living tissue and in a process known as ‘bone turnover’ bone is broken down and replaced. This balanced process is essential for keeping bones healthy and in good repair. Bone turnover is controlled by many factors in the body including the hormone thyroxine (produced by the thyroid gland).

Read more on Healthy Bones Australia website

Hyperthyroidism (overactive thyroid)

Hyperthyroidism is a health condition where your thyroid becomes overactive and produces too many hormones. It is a serious health condition that is fatal if left undiagnosed or untreated.

Read more on WA Health website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Queensland Government logo Government of South Australia, health department logo Tasmanian government logo Victorian government logo Government of Western Australia, health department logo

Healthdirect Australia acknowledges the Traditional Owners of Country throughout Australia and their continuing connection to land, sea and community. We pay our respects to the Traditional Owners and to Elders both past and present.