Hypothyroidism

Key facts

• Hypothyroidism means the thyroid gland is not making enough thyroid hormone, which sets the pace of much of the body.
• Common signs build gradually: tiredness, feeling cold, weight gain, dry skin, constipation and low mood, often mistaken for stress or ageing.
• It is more common in women and tends to appear in middle age, though it can start at any time.
• Treatment replaces the missing hormone, usually with levothyroxine taken once a day, with doses matched to blood test results over time.

What hypothyroidism is

Hypothyroidism means the thyroid gland is not making enough thyroid hormone. That hormone sets the pace of much of the body, so when levels run low, things slow down. Common signs include tiredness, feeling cold, weight gain, dry skin, constipation, low mood and slower thinking. They build gradually, which is why many people put them down to stress or ageing before a blood test points to the thyroid. It is more common in women and tends to appear in middle age, though it can start at any time.

How hypothyroidism is treated

Treatment replaces the hormone the thyroid is no longer making. The standard option is levothyroxine, a synthetic form of the main thyroid hormone, taken once a day. Some people who do not feel fully well on it alone also use liothyronine, a faster-acting hormone. Doses are matched to your blood results and reviewed over time, so taking the tablet at the same time each day, usually on an empty stomach, helps keep levels steady. You can see the full range on our thyroid health page.

Lifestyle factors that help

Adequate iodine intake supports normal thyroid hormone production, and a balanced diet is a useful complement to treatment, though it does not replace it. Staying consistent with medication timing matters more than any single dietary change.

When to see a doctor

See a doctor if you notice persistent fatigue, unexplained weight gain, feeling unusually cold or low mood that does not lift, since these can point to an underactive thyroid that a blood test will confirm.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.