Many symptoms of an underactive thyroid (hypothyroidism) are the same as those of other conditions, so it can easily be confused for something else.

Symptoms usually develop slowly and you may not realise you have a medical problem for several years.

Common symptoms include:

• tiredness
• being sensitive to cold
• weight gain
• constipation
• depression
• slow movements and thoughts
• muscle aches and weakness
• muscle cramps
• dry and scaly skin
• brittle hair and nails
• loss of libido (sex drive)
• pain, numbness and a tingling sensation in the hand and fingers (carpal tunnel syndrome)
• irregular periods or heavy periods

Elderly people with an underactive thyroid may develop memory problems and depression. Children may experience slower growth and development. Teenagers may start puberty earlier than normal.

If you have any of these symptoms, see a GP and ask to be tested for an underactive thyroid.

It's unlikely that you'd have many of the later symptoms of an underactive thyroid, because the condition is often identified before more serious symptoms appear.

Later symptoms of an underactive thyroid include:

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