An overactive thyroid (hyperthyroidism) is usually treatable.

You'll normally be referred to an endocrinologist (specialist in hormone conditions) to plan your treatment.

The main treatments are:


Radioiodine treatment


These are outlined below. You can also read a summary of the pros and cons of the treatments for an overactive thyroid, allowing you to compare the options.


Medicines called thionamides are a common treatment for an overactive thyroid. These stop your thyroid producing excess hormones.

The main types used are carbimazole and propylthiouracil.

You'll usually need to take the medicine for a month or two before you notice any benefit. You may be given another medication called a beta-blocker to quickly relieve your symptoms in the meantime.

Once your thyroid hormone level is under control, your dose may be gradually reduced and then stopped. But some people need to continue taking medication for several years or possibly for life.

Side effects

During the first couple of months, some people experience the following side effects:

These should pass as your body gets used to the medication.

A less common but more serious side effect is a sudden drop in your white blood cell level (agranulocytosis), which can mean you're very vulnerable to infections.

Contact your doctor immediately if you get symptoms of agranulocytosis, such as a fever, sore throat or persistent cough so a blood test can be carried out to check your white blood cell level.

Radioiodine treatment

Radioiodine treatment is where radiation is used to damage your thyroid, reducing the amount of hormones it can produce. It's a highly effective treatment that can cure an overactive thyroid.

You're given a drink or capsule that contains a low dose of radiation, which is then absorbed by your thyroid. Most people only require a single treatment.

It can take a few weeks or months for the full benefits to be felt, so you may need to take one of the medications mentioned above for a short time.

The dose of radiation you're given is very low, but there are some precautions you'll need to take after treatment:

  • avoid prolonged close contact with children and pregnant women for a few days or weeks
  • women should avoid getting pregnant for at least six months
  • men shouldn't father a child for at least four months

Radioiodine treatment isn't suitable if you're pregnant or breastfeeding. It's also not suitable if your overactive thyroid is causing severe eye problems.


Occasionally, surgery to remove all or part of your thyroid may be recommended.

This may be the best option if:

  • your thyroid gland is severely swollen (a large goitre)
  • you have severe eye problems resulting from an overactive thyroid
  • you can't have the other treatments mentioned above
  • your symptoms come back after trying the treatments mentioned above

Removing the entire thyroid gland is normally recommended, as this cures an overactive thyroid and means there's no chance of the symptoms coming back.

But as a result, you'll need to take medication for the rest of your life to make up for not having a thyroid – these are the same medications used to treat an underactive thyroid.

Page last reviewed: 22/09/2016

Next review due: 22/09/2019