An overactive thyroid (hyperthyroidism) means the thyroid gland makes too much hormone, so the body works too fast. It is more common in women aged 20 to 50, and the most common cause is Graves disease. If untreated it can strain the heart and weaken the bones, but medicines and other treatments work well.
Symptoms
Fast or irregular heartbeat and palpitations
Weight loss despite a good appetite
Feeling hot and sweating a lot
Shaking hands
Nervousness, irritability and poor sleep
Loose stools
Bulging or gritty eyes (in Graves disease)
Swelling in the neck
Causes
Graves disease (the immune system over-stimulates the thyroid)
Thyroid nodules or a lumpy goitre that make extra hormone
Inflammation of the thyroid (thyroiditis), often temporary
Taking too many thyroid hormone tablets
Prevention
Most causes cannot be prevented
Do not smoke: smoking makes Graves eye disease worse
Take thyroid tablets only at the dose your doctor prescribed
See a doctor early if you notice symptoms, especially palpitations and weight loss
Treatment
Anti-thyroid tablets such as carbimazole, with regular blood tests
Beta-blocker tablets to slow the heart and ease shaking, if the doctor advises
Radioactive iodine or surgery for some people
Stop treatment only when the doctor says so, never on your own
Women who are pregnant or planning pregnancy need a special choice of medicine
Common questions
Is an overactive thyroid dangerous?
If untreated, it can cause an irregular heartbeat, heart failure, weak bones and, rarely, a life-threatening crisis called thyroid storm. With treatment most people return to normal health.
How long does treatment with tablets last?
Anti-thyroid tablets are usually taken for 12 to 18 months, with regular blood tests. Some people stay well after stopping; others need radioactive iodine or surgery later.
