What are the symptoms of an underactive thyroid?

Symptoms often develop slowly and can include tiredness, weight gain, feeling cold, dry skin and hair, constipation, muscle aches and low mood. Because these are common and non-specific, a blood test is needed to confirm the cause.

What causes an underactive thyroid?

The most common cause is the immune system attacking the thyroid gland. It can also follow some thyroid treatments or, less commonly, be linked to other factors. It is more common in women and becomes more likely with age.

How is an underactive thyroid treated?

It is usually treated with a daily tablet of a hormone called levothyroxine, which replaces the hormone the thyroid is not making. Most people feel much better once the right dose is found, and treatment is often lifelong.

Do I need treatment for life?

In most cases yes, but the medication simply replaces a hormone your body needs, and regular blood tests ensure your dose is right. Many people live completely normally once treated.

Underactive thyroid (hypothyroidism)

Quick answer

What is underactive thyroid (hypothyroidism)?

An underactive thyroid (hypothyroidism) is when the thyroid gland does not produce enough thyroid hormone. This can cause tiredness, weight gain, feeling cold and low mood. It is diagnosed with a blood test and is usually treated effectively with a daily hormone replacement tablet.

What is an underactive thyroid?

The thyroid is a small gland in the neck that produces hormones controlling how your body uses energy. An underactive thyroid, or hypothyroidism, is when it does not make enough of these hormones. This slows down many body processes and can cause a range of symptoms. It is a common condition, particularly in women and as people get older.

Symptoms

Symptoms usually develop gradually and can be easy to miss. They may include:

tiredness and low energy
weight gain
feeling the cold
dry skin and hair
constipation
muscle aches
low mood and difficulty concentrating

Because these symptoms are common and can have many causes, a blood test is needed to confirm whether the thyroid is responsible.

How it is diagnosed

An underactive thyroid is diagnosed with a blood test that measures thyroid hormone levels. If your GP suspects a thyroid problem from your symptoms, this simple test usually gives a clear answer.

How it is treated

Treatment is usually straightforward and effective. It involves taking a daily tablet of a hormone called levothyroxine, which replaces what the thyroid is not producing. Your GP will check your blood levels and adjust the dose until it is right for you. Once stabilised, most people feel substantially better.

Living with an underactive thyroid

For most people, treatment is lifelong but simple, with regular blood tests to keep the dose correct. With the right treatment, an underactive thyroid usually has little impact on daily life.

Common questions

What are the symptoms of an underactive thyroid?: Symptoms often develop slowly and can include tiredness, weight gain, feeling cold, dry skin and hair, constipation, muscle aches and low mood. Because these are common and non-specific, a blood test is needed to confirm the cause.
What causes an underactive thyroid?: The most common cause is the immune system attacking the thyroid gland. It can also follow some thyroid treatments or, less commonly, be linked to other factors. It is more common in women and becomes more likely with age.
How is an underactive thyroid treated?: It is usually treated with a daily tablet of a hormone called levothyroxine, which replaces the hormone the thyroid is not making. Most people feel much better once the right dose is found, and treatment is often lifelong.
Do I need treatment for life?: In most cases yes, but the medication simply replaces a hormone your body needs, and regular blood tests ensure your dose is right. Many people live completely normally once treated.

Sources

NHS — Underactive thyroid (hypothyroidism)