Treatment for overactive thyroid (hyperthyroidism) aims to return the level of thyroid hormones in your blood to normal. You may also need treatment for any associated conditions, such as swelling of your thyroid gland (goitre).
Treating subclinical overactive thyroid
If you are diagnosed with subclinical overactive thyroid, you may not need any treatment for your condition.
In most cases, the reduced level of thyroid-stimulating hormone (TSH) in your blood will eventually return to normal within a couple of months without the need for treatment, and your subclinical hyperthyroidism will resolve by itself.
However, as subclinical overactive thyroid can progress to overt (fully developed) overactive thyroid, you will need to return to your GP one to two months after your diagnosis for a thyroid function test, so your condition can be monitored.
If you still have lower than normal levels of TSH in your blood after one to two months, without raised levels of thyroid hormones, you will need to return to your GP regularly for further testing.
This may be once every three to six months, or more often if you are elderly or you have an underlying condition that affects the heart, arteries and veins, such as coronary heart disease or stroke.
Your GP may also suggest further assessments to determine the cause of your subclinical overactive thyroid. If your GP is concerned that your condition has not resolved, they may refer you for specialist treatment.
Treating overt overactive thyroid
You will be diagnosed with overt overactive thyroid if the thyroid function test finds that your levels of TSH are low and your levels of thyroid hormone (thyroxine or triiodothyronine) are high.
In this case, your GP will refer you for specialist treatment. You may also be referred for specialist treatment if:
- you have Graves' ophthalmopathy (eye problems such as double vision and prominent or bulging eyes caused by Graves' disease. See Overactive thyroid - complications
- you are pregnant, planning a pregnancy or have recently given birth and you have existing or newly diagnosed overactive thyroid
- you have overactive thyroid that is caused by a secondary substance, such as amiodarone
- you have an underlying condition, such as coronary heart disease
You may need to receive emergency treatment in hospital if you have any of the symptoms of a thyroid storm (see Overactive thyroid - symptoms). This is a rare but serious reaction that can occur as a result of undiagnosed or poorly controlled overactive thyroid.
Your specialist will determine the best method of treatment based on your symptoms and the amount of extra thyroid hormone in your blood. The methods of treating overactive thyroid are outlined below.
Thionamides (carbimazole and propylthiouracil)
Thionamides are a common treatment for overactive thyroid. They are a type of medication that stops your thyroid gland producing excess amounts of thyroxine or triiodothyronine.
As thionamides affect the production of thyroid hormone rather than their current levels, you will need to take them for several weeks before you notice an improvement.
You will probably need to take carbimazole or propylthiouracil for four to eight weeks before your thyroid gland is under control. As the amount of medication needed to reduce the production of thyroid hormone varies from person to person, you may need to take it for a shorter or longer period of time than this.
Once the production of thyroid hormone from your thyroid gland is under control, your specialist may gradually reduce the dosage of medication.
If your condition is not under control, you may need to continue taking carbimazole or propylthiouracil for a long time. You may also have to take this medication in the long term if your overall health prevents you from using other forms of treatment.
In rare cases, you may experience several side effects from taking carbimazole or propylthiouracil, although these are usually mild. Side effects may include:
- mild skin rash
- pain in your joints
- nausea
- itchy skin
In very rare cases, carbimazole or propylthiouracil can cause a serious blood condition known as agranulocytosis (a sudden drop in white blood cells). This usually occurs in the first three months of treatment.
Seek urgent medical attention if you are taking a thionamide and you develop:
- fever
- sore throat
- mouth ulcers
- other signs of infection
Beta-blockers
Beta-blockers, such as propranolol or atenolol, can relieve some of the symptoms of overactive thyroid, including tremor (shaking and trembling), rapid heartbeat and hyperactivity.
Your specialist may prescribe you a beta-blocker to relieve your symptoms while you are undergoing a diagnostic assessment, or until your thyroid gland is brought under control by treatment with a thionamide. However, beta-blockers are not suitable if you have asthma.
Beta-blockers can sometimes cause side effects, including:
- nausea
- fatigue (extreme tiredness)
- cold hands and feet
- trouble sleeping, sometimes with nightmares
Radioiodine treatment
Radioiodine treatment is a form of radiotherapy that is used to treat most types of overactive thyroid. It contains radioactive iodine, which builds up in your thyroid gland and shrinks it, reducing the amount of thyroid hormone that it can make.
If you have radioiodine treatment, you will be given either a drink or a capsule of radioiodine to swallow. The dose of radioactivity contained in the radioiodine is very low and is not harmful.
Radioiodine treatment is not suitable if you are pregnant or breastfeeding, and may not be suitable if you have eye problems, such as double vision or prominent (bulging) eyes.
Women should avoid getting pregnant for at least six months after having radioiodine treatment. Men should not father a child for at least four months after having radioiodine treatment.
Surgery (thyroidectomy)
Surgery to remove all or part of the thyroid gland is known as a total or near-total thyroidectomy. It is a permanent cure for recurrent overactive thyroid.
Your specialist may recommend surgery if your thyroid gland is severely swollen (a large goitre) and is causing problems in your neck.
A thyroidectomy may also be suggested if:
- you have toxic multinodular goitre or a toxic thyroid nodule (adenoma)
- you also have cancer of the thyroid
The goal of surgery is to remove just enough of your thyroid gland to lower the production of thyroxine to normal. If too much of the thyroid gland is taken, you may get underactive thyroid (hypothyroidism). This happens when not enough thyroid hormones are produced.
However, if underactive thyroid occurs, thyroid hormone tablets can be taken to keep your thyroid levels normal (see the Health A-Z topic on Underactive thyroid - treatment).
