Antithyroid Medication | Types, Uses and Side Effects (2023)

What are antithyroid medicines for hyperthyroidism?

Antithyroid medicines are used to treat an overactive thyroid gland (hyperthyroidism), also known as thyrotoxicosis. There are different causes of hyperthyroidism. The causes of hyperthyroidism where antithyroid medicines are used include:

  • Graves' disease - the most common cause of hyperthyroidism.
  • Severe hyperthyroidism - known as thyrotoxic crisis or thyroid storm.
  • In some people with thyroid nodules - lumps on the thyroid gland which may release thyroid hormones.
  • The treatment of some forms of cancer.

See the separate leaflet called Overactive Thyroid Gland (Hyperthyroidism).

Are there different types of antithyroid medication for hyperthyroidism?

The most commonly used antithyroid medicine in the UK is carbimazole, followed by propylthiouracil. Carbimazole and propylthiouracil belong to a group (class) of medicines called thionamides. Thionamides have similar actions on the thyroid gland.

How does antithyroid medication work?

Thyroxine (also known as T4) is a body chemical (hormone) made by the thyroid gland. It is carried around the body in the bloodstream. It helps to keep the body's functions (the metabolism) working at the correct pace. Many cells and tissues in the body need thyroxine to keep them working correctly.

'Hyperthyroidism' means an overactive thyroid gland. When the thyroid gland is overactive it makes too much thyroxine. The extra thyroxine causes many of the body's functions to speed up. (In contrast, if you have hypothyroidism, you make too little thyroxine. This causes many of the body's functions to slow down.)

Thionamides such as carbimazole reduce the amount of hormone released by the thyroid gland. Carbimazole does not affect the thyroxine which is already made and stored, but reduces further production. Therefore, it may take four to eight weeks of treatment for your thyroxine level to come down to normal.

Which is the best treatment for an overactive thyroid gland?

Carbimazole is the most widely prescribed antithyroid medicine in the UK. Propylthiouracil can be used instead if you develop a side-effect to carbimazole, or it may be used in a thyrotoxic crisis. Propylthiouracil is also used for an overactive thyroid gland in pregnancy. Your doctor will advise you on which is the most suitable for you.

(Video) Thyroid & Antithyroid Drugs - NCLEX Review

How do I take antithyroid medicine?

Getting the right balance of thyroid hormone in your blood can take time.

Doctors have two main methods of trying to get the balance right. The first involves taking an initial high dose of carbimazole to reduce the amount of thyroxine in your blood. This dose is taken until the hormone levels in your blood have stabilised, usually about four to eight weeks later. Because your body needs a certain amount of thyroxine to function properly, the high dose is then slowly decreased. Usually, your hormone levels will be checked by a blood test every month or so. The dose of medicine you are taking will be changed depending upon the results of your thyroid hormone levels. The aim of this treatment is to keep you on the lowest level of antithyroid medicine necessary. This treatment method is called 'titration'.

It can be difficult for a doctor to judge just the right dose of carbimazole to give in each case. Too much treatment may make the thyroxine level go too low. Not enough treatment means the level remains higher than normal. This is the reason for the regular blood tests and careful monitoring.

The second option is to deliberately take a high dose of carbimazole each day. This stops the thyroid gland making any thyroxine. Your doctor can then prescribe a daily dose of thyroxine to keep the blood level of thyroxine normal. This 'over-treatment' coupled with taking replacement thyroxine is called 'block and replace' and is a popular option.

It is generally thought that the 'block and replace' method results in better control of thyroid hormone levels. However, the risk of experiencing an adverse effect from the higher dose of antithyroid medicine may be higher.

How quickly does antithyroid medication work?

These medicines should have some effect on your symptoms around 10 to 14 days after treatment starts. Thyroid hormone levels are usually stabilised within four to eight weeks of taking the medication.

How long is treatment needed for an overactive thyroid gland?

This may vary depending on the way in which you take your medicines. Hyperthyroidism is what is known as a relapsing-remitting illness. This means that the symptoms of the condition may get better (remit) or get worse (relapse).

(Video) Thyroid and Anti-Thyroid Medications - Pharmacology (Pharm) - Endocrine System - @Level Up RN

Medical evidence suggests that about half of people treated by the titration method will get better (achieve remission) after 18 to 24 months of treatment. However, about half of those treated by the 'block and replace' method will achieve remission within six months of treatment. Your doctor will advise you on which treatment option may be suitable for you. 'Block and replace' therapy is not suitable in pregnancy.

Will hyperthyroidism return after treatment with antithyroid medicines?

As mentioned before, having an overactive thyroid gland (hyperthyroidism) is generally a relapsing-remitting illness, which means symptoms may return after treatment. If you feel unwell following treatment you should return to your doctor. Your GP should be able to advise you on the type of symptoms to look out for.

What would happen if I didn't take antithyroid medicines?

It is usually advisable to treat an overactive thyroid gland (hyperthyroidism). Untreated hyperthyroidism can cause significant problems with your heart and other organs. It may also increase your risk of complications should you become pregnant. However, in many cases there are other treatment options. That is, radioactive iodine or surgery may be suitable options.

See the separate leaflet called Overactive Thyroid Gland (Hyperthyroidism) for details of these other treatment options.

What are the possible side-effects of antithyroid medication?

Most people who take antithyroid medicines do not experience any side-effects. The side-effects that most commonly occur are:

  • Rash
  • Pruritus (itching)
  • Mild stomach upset
  • Headache
  • Painful joints

The above side-effects are usually not serious and often go, even if you continue with the medication.

A rare but serious side-effect is an effect on the blood-making cells. This can drastically reduce the number of blood cells in your body, including the cells that fight off infection and those that help to stop bleeding. Therefore, you must stop the medicine and report this to your doctor immediately, if you develop:

(Video) Antithyroid Drugs: Propylthiouracil, Carbimazole & Methimazole

  • A sore throat.
  • Mouth ulcers.
  • Unexplained bruising or bleeding.
  • Rash.
  • High temperature (fever).
  • Any other signs of infection.

As noted above, a mild rash is a common side-effect. The rash associated with this rare but serious effect on blood-making cells is different. Therefore, when taking an antithyroid medicine, always report a rash to a doctor who can then decide if it is a common and minor problem or the more serious rash.

Can I buy antithyroid medicines or do I need a prescription?

You cannot buy these medicines. They are only available from your chemist, with a doctor's prescription, and are usually started by a specialist doctor.

Who can and cannot take antithyroid medicines?

Pregnant women or those planning a baby should seek the advice of their GP, as these medicines are able to cross the placenta. The placenta is the organ that provides nourishment and oxygen to a baby in the womb (uterus). Antithyroid medicines may not be suitable for people with some forms of liver or kidney disease.

A full list of people who should not take antithyroid medicines is included with the information leaflet that comes with your medicine. Read this to be sure you are safe to take it.

These medicines sometimes react with other medicines that you may take. So, make sure your doctor knows of any other medicines that you are taking, including ones that you have bought rather than been prescribed.

How to use the Yellow Card Scheme

If you think you have had a side-effect to one of your medicines you can report this on the Yellow Card Scheme. You can do this online at www.mhra.gov.uk/yellowcard.

The Yellow Card Scheme is used to make pharmacists, doctors and nurses aware of any new side-effects that medicines or any other healthcare products may have caused. If you wish to report a side-effect, you will need to provide basic information about:

  • The side-effect.
  • The name of the medicine which you think caused it.
  • The person who had the side-effect.
  • Your contact details as the reporter of the side-effect.

It is helpful if you have your medication - and/or the leaflet that came with it - with you while you fill out the report.

(Video) Hyperthyroidism treatment medications ~pharmacology~

Are there homeopathy treatments for overactive thyroid instead of thyroid medicine?

When you look up anything these days, we all know that there will be some kind of 'natural remedy' that promises a great cure without all those 'nasty medicines' that doctors prescribe. Be careful: an overactive thyroid gland is a potentially serious condition, particularly for your heart. It's best to get an opinion from a legitimate doctor, preferably one who is impartial and paid by a state-funded system like the NHS, before trying any homeopathic treatments.

Can I use thyroid medicines for weight loss?

When someone has an underactive thyroid gland,they are given a medicine to boost their levels of thyroxine. This medicine is called levothyroxine. Sometimes this can help the person lose weight, if their underactive thyroid gland has caused them to put on weight. See the separate leaflet called Underactive Thyroid Gland (Hypothyroidism).

Unfortunately, as you can imagine, some unsavoury people get hold of levothyroxine and then try to sell it as a 'weight loss' cure.

Be careful: it's true that taking lots of levothyroxine could make you lose weight but it will also be very harmful to your body. It will turn you into having an overactive thyroid gland (hyperthyroidism) with all of the bad effects of that condition that have been discussed in this leaflet.

(Video) Long-Term Use of Antithyroid Medications

The best and healthiest way to lose weight is to eat healthily.See the separate leaflet called Weight Loss (Weight Reduction) for help on losing weight.

FAQs

What are the side effects of antithyroid medications? ›

Minor side effects — Up to 15 percent of people who take an antithyroid drug have minor side effects. Both methimazole and propylthiouracil can cause itching, rash, hives, joint pain and swelling, fever, changes in taste, nausea, and vomiting.

What are antithyroid drugs used for? ›

Antithyroid medications—sometimes written as anti-thyroid medications—are a common treatment for hyperthyroidism, particularly if you have an ongoing form of hyperthyroidism caused by Graves' disease or a goiter. The goal of antithyroid medications is to prevent the thyroid from producing excess amounts of hormone.

How effective are antithyroid drugs? ›

One study showed antithyroid drugs are highly effective at normalizing triiodothyronine and thyroxine levels within 4 to 8 weeks.

Which food should a patient avoid while taking antithyroid medications? ›

Avoid other foods high in iodine such as:
  • milk and dairy.
  • cheese.
  • egg yolks.
  • iodized salt.
  • iodized water.
  • some food colorings.

How long do antithyroid drugs take to work? ›

How quickly does antithyroid medication work? These medicines should have some effect on your symptoms around 10 to 14 days after treatment starts. Thyroid hormone levels are usually stabilised within four to eight weeks of taking the medication.

When can I stop taking anti thyroid medication? ›

You will usually continue on antithyroid drugs alone for up to 18 months, or on block and replace therapy for six to 12 months. If you have Graves' disease there is about a 30-50% chance that you will have no further problems with your thyroid after a single course of antithyroid drugs.

How much is antithyroid medication? ›

Medication for hyperthyroidism can range from about $4 to $93, and medication for hypothyroidism can range from about $16 to $25 for 30 tablets. Members get access to low-cost urgent care visits, affordable lab testing, and discounted prescriptions with Mira, all for $45 per month.

Which medicine is best for hyperthyroidism? ›

Medicines called thionamides are commonly used to treat an overactive thyroid. They stop your thyroid producing excess hormones. The main types used are carbimazole and propylthiouracil. You'll usually need to take the medicine for 1 to 2 months before you notice any benefit.

What causes overactive thyroid? ›

Graves' disease is the most common cause of overactive thyroid. It can run in families and can occur at any age, although it is most common in women aged 20-40 years old. You are more likely to develop Graves' disease if you smoke. Graves' disease is an autoimmune condition.

Can you live a normal life with hyperthyroidism? ›

In general, people with hyperthyroidism have a good quality of life, with no particular limitations in terms of diet, exercise, work or sexual activity. During the active symptomatic phase of hyperthyroidism, the medical team may recommend avoiding strenuous physical exercise.

Can hyperthyroidism be cured? ›

Can hyperthyroidism be cured? Yes, there is a permanent treatment for hyperthyroidism. Removing your thyroid through surgery or destroying your thyroid through medication will cure hyperthyroidism.

What is the first line treatment for hyperthyroidism? ›

Antithyroid drugs, radioactive iodine, and surgery are the main treatment options for persistent hyperthyroidism (Table 3).

Which fruit is good for thyroid? ›

Apples, pears, plums and citrus fruits are abundant with pectins, which help with detoxifying the body of mercury – one of the most critical metals that have been connected to thyroid problems.

Which vegetable is good for thyroid? ›

Cruciferous vegetables, such as kale, Brussels sprouts, radishes, and cauliflower. Also known as goitrogenic foods (foods that can help lower thyroid hormone production), they may inhibit your thyroid gland's ability to process iodine and produce thyroid hormones—potentially easing symptoms of hyperthyroidism.

Is banana good for thyroid? ›

Hypothyroid persons can take all fruits including banana in moderation.

What happens if I miss my thyroid medication for a month? ›

Missing doses of thyroid medication can cause hypothyroidism symptoms to return. Taking your medication as prescribed can help avoid this. If you miss multiple doses of your thyroid medication, call your healthcare provider. They can let you know if your dose should be adjusted.

Do antithyroid drugs cause weight gain? ›

Treatment of hyperthyroidism with RAI or anti-thyroid medications is associated with an increased risk of gaining weight and even developing obesity. This risk is slightly higher with RAI therapy compared to medications.

How many years can you take methimazole? ›

A recent randomized clinical trial reported that 5-year continuous methimazole (MMI) therapy is accompanied with 84% remission up to 4 years after drug withdrawal [14]. However, the optimal duration of ATD therapy is still debatable.

What happens if you stop taking hyperthyroid medicine? ›

When your doctor asks you to stop your thyroid medication, your hormone level will decrease significantly, and this may lead to signs and symptoms of acute hypothyroidism. Weakness, lethargy, cold intolerance, paleness, dry skin, coarse hair, and constipation can occur with acute hypothyroidism.

Is 10 mg of methimazole a lot? ›

Typical dosing for methimazole (Tapazole)

The dose of methimazole (Tapazole) for adults ranges from 5 to 40 mg by mouth per day depending on how severe your hyperthyroidism is. The dose is taken in 3 divided doses every 8 hours.

Do I have to take methimazole forever? ›

Long-term therapy with methimazole is not usually considered in treating patients with a toxic nodular goiter since this will never go into remission. However, methimazole has been shown to be safe for long term use in patients with Graves' disease.

What is the best time of day to take methimazole? ›

Food in your stomach may change the amount of methimazole that is able to enter the bloodstream. To make sure that you always get the same effects, try to take methimazole at the same time in relation to meals every day. That is, always take it with meals or always take it on an empty stomach.

Can you remove your thyroid? ›

If you need only part of your thyroid removed (partial thyroidectomy), your thyroid may work normally after surgery. If you need your entire thyroid removed (total thyroidectomy), you need daily treatment with thyroid hormone to replace your thyroid's natural function.

What happens if you stop taking methimazole? ›

If you skip or stop your medicine entirely, you can experience a number of short-term and long-term consequences, including: Debilitating weight loss. Dramatically increased appetite and thirst. Nervousness, anxiety, panic attacks.

Is milk good for hyperthyroidism? ›

Milk is a calcium-rich food that is very healthy. However, whole milk and whole milk are often high in fat, which people with hyperthyroidism have poor fat digestibility and are not recommended for people with hyperthyroidism.

Does stress cause hyperthyroidism? ›

As mentioned earlier, hyperthyroidism isn't caused by stress, but that doesn't mean the two aren't related. For those that already have symptoms of hyperthyroidism, physical or mental stress can make them even worse.

How can I reduce hyperthyroidism? ›

Possible treatments include:
  1. Radioactive iodine. Taken by mouth, radioactive iodine is absorbed by your thyroid gland, where it causes the gland to shrink. ...
  2. Anti-thyroid medications. ...
  3. Beta blockers. ...
  4. Surgery (thyroidectomy).
14 Nov 2020

What is normal thyroid level? ›

These levels are influenced by many factors that affect protein levels in the body, including medications, sex hormones, and liver disease. A normal Total T4 level in adults ranges from 5.0 to 12.0μg/dL. A normal Total T3 level in adults ranges from 80-220 ng/dL.

Is an overactive thyroid serious? ›

In rare cases, an undiagnosed or poorly controlled overactive thyroid can lead to a serious, life-threatening condition called a thyroid storm. This is a sudden flare-up of symptoms that can be triggered by: an infection.

What happens when thyroid is high? ›

Hyperthyroidism (overactive thyroid) occurs when your thyroid gland produces too much of the hormone thyroxine. Hyperthyroidism can accelerate your body's metabolism, causing unintentional weight loss and a rapid or irregular heartbeat. Several treatments are available for hyperthyroidism.

What is the safest treatment for hyperthyroidism? ›

Radioactive iodine treatment

It's a highly effective treatment that can cure an overactive thyroid. You're given a drink or capsule that contains iodine and a low dose of radiation, which is absorbed by your thyroid. Most people only need a single treatment.

What are the side effects of methimazole? ›

Methimazole may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
  • skin rash.
  • itching.
  • abnormal hair loss.
  • upset stomach.
  • vomiting.
  • loss of taste.
  • abnormal sensations (tingling, prickling, burning, tightness, and pulling)
  • swelling.
15 Jul 2017

What are the long-term effects of methimazole? ›

Some of the more frequently reported adverse reactions have included skin rash, urticaria, nausea, loss of taste, and abnormal loss of hair.

How long should you stay on methimazole? ›

A recent randomized clinical trial reported that 5-year continuous methimazole (MMI) therapy is accompanied with 84% remission up to 4 years after drug withdrawal [14]. However, the optimal duration of ATD therapy is still debatable.

Can hyperthyroidism be cured? ›

Can hyperthyroidism be cured? Yes, there is a permanent treatment for hyperthyroidism. Removing your thyroid through surgery or destroying your thyroid through medication will cure hyperthyroidism.

Does stress cause hyperthyroidism? ›

As mentioned earlier, hyperthyroidism isn't caused by stress, but that doesn't mean the two aren't related. For those that already have symptoms of hyperthyroidism, physical or mental stress can make them even worse.

Who is the best doctor for thyroid? ›

An endocrinologist is particularly knowledgeable about the function of the thyroid gland and the body's other hormone-secreting glands.

What is methimazole 5 mg used for? ›

Methimazole is used to treat hyperthyroidism, a condition where the thyroid gland produces too much thyroid hormone. It is also used before thyroid surgery or radioactive iodine treatment. Methimazole is an antithyroid medicine. It works by making it harder for the body to make thyroid hormone.

Can thyroid medicine affect your kidneys? ›

Drugs used in thyroid dysfunction may result in renal dysfunction or require dose reduction in CKD. The variable association of low T3 to inflammation, endothelial dysfunction, and poor survival in CKD and transplant patients is of importance.

When is the best time of day to take methimazole? ›

Food in your stomach may change the amount of methimazole that is able to enter the bloodstream. To make sure that you always get the same effects, try to take methimazole at the same time in relation to meals every day. That is, always take it with meals or always take it on an empty stomach.

What happens if you stop methimazole? ›

Withholding the medicine for more than three days, he says, may cause a worsening of the hyperthyroidism. "In our practice, we usually discontinue methimazole for 48 hours before radioiodine use with good results," he says.

Can I take methimazole for life? ›

Long-term therapy with methimazole is not usually considered in treating patients with a toxic nodular goiter since this will never go into remission. However, methimazole has been shown to be safe for long term use in patients with Graves' disease.

Is methimazole harmful to humans? ›

The answer from drug-safety experts is that methimazole in any form should be handled with caution. The medication impedes the body from using iodine to make thyroid hormone, thereby inhibiting synthesis of the hormone.

Is 10 mg of methimazole a lot? ›

Typical dosing for methimazole (Tapazole)

The dose of methimazole (Tapazole) for adults ranges from 5 to 40 mg by mouth per day depending on how severe your hyperthyroidism is. The dose is taken in 3 divided doses every 8 hours.

Can methimazole damage the liver? ›

Methimazole is also capable of causing clinically apparent, idiosyncratic liver injury. The onset of hepatotoxicity is usually within 2 to 12 weeks of starting and the pattern of enzyme elevations is typically cholestatic or mixed, although hepatocellular patterns have also been described.

What happens when you stop taking medication for hyperthyroidism? ›

When your doctor asks you to stop your thyroid medication, your hormone level will decrease significantly, and this may lead to signs and symptoms of acute hypothyroidism. Weakness, lethargy, cold intolerance, paleness, dry skin, coarse hair, and constipation can occur with acute hypothyroidism.

Videos

1. Effectiveness of Thyroid Medications: Mayo Clinic Radio
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2. Is Long-term Antithyroid Use the Best Treatment for Graves Disease?
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3. Does allopathic thyroid medication have any side effect? - Dr. Sanjay Panicker
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4. Hyperthyroidism & Thyroid Storm Signs & Symptoms (& Why They Occur)
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6. When to take your Thyroid Tablet ? - Dr.Ravi Sankar Endocrinologist MRCP(UK) CCT - GIM (UK)
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