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Thyroid medication

Thyroid medication can be separated into two groups: treatments for overactive thyroids (hyperthyroidism) and medications for underactive thyroids (hypothyroidism).

  1. Treats over and underactive thyroids.
  2. Can help prevent the amount of thyroid hormone produced.
  3. Can inhibit the production of too much thyroid hormone.

If you have any concerns about thyroid medication or the conditions they treat, you can speak with one of our GMC-registered clinicians via our online video consultation service. They are available for appointments between 9.30am-4.30pm, Monday to Friday. 

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Product information

What is thyroid medication?

Thyroid medication is used to treat either an overactive or an underactive thyroid in the body. Thioamides are a medication for overactive thyroids, which work by preventing the production of too much thyroid hormone. Underactive thyroids (hypothyroidism) are caused by a lack of the thyroid hormone thyroxine. It can be treated with the use of levothyroxine, a synthetic version of the naturally occurring hormone. 

Overactive thyroids can be caused by a number of conditions, most commonly Graves' disease and thyroid nodules. Underactive thyroids are usually caused by the immune system attacking the thyroid gland.

What is Graves' disease? 

Graves' disease makes up around 75% of all cases of hyperthyroid conditions. Although in very rare cases it can cause severe health problems, it can be well-managed with treatment. Symptoms of Graves' disease include the loss of control of your emotions, which can be overwhelming for some people, particularly if the condition has yet to be diagnosed and you are unsure what is going on.

Other common symptoms are weight loss, a rapid heartbeat, anxiety, insomnia, diarrhoea, loss of breath, bulging eyes, visual problems, fatigue, shakiness, muscle weakness and swelling of the neck.

What causes Graves' disease?

It’s not entirely clear what causes Graves' disease, but it is linked to the immune system. It’s thought that the body mistakes the thyroid hormones for an invading substance and attacks the thyroid by mistake. This leads to the thyroid producing more of the hormone thyroxine. 

The thyroid gland is key in maintaining the body’s metabolism, which regulates the heartbeat, the burning of calories during rest and various bodily functions. As such, when too much of the hormone is produced, it can have a significant impact.

How is Graves' disease diagnosed? 

In order for Graves' disease to be diagnosed, your GP may arrange for you to have a blood test (a thyroid function test) to assess your thyroid hormone levels. If this proves inconclusive, a radioactive iodine scan may be required. To rule out cysts and tumours being the cause of the symptoms, an ultrasound may also be suggested. 

How is Graves' disease treated?

There are two medications that treat hyperthyroidism: carbimazole and propylthiouracil. The dosage for these treatments will likely start at a high level and then be reduced over time. Your doctor will need to check your thyroid hormone levels every six to eight weeks and the length of treatment will last for at least 12 months. 

These medications can put a strain on the body’s immune system by lowering white blood cell count; if you experience a fever or sore throat, you should report it as soon as possible.

In around half of cases, thyroid function will return to normal once treatment has ended. Other treatment will be required if these medications prove ineffective.

Beta blockers are a common medication for managing symptoms, but are likely to be a short-term measure only. Beta blockers are particularly good for slowing down the heart rate and reducing anxiety.

Other treatments for hyperthyroidism include the use of radioactive iodine or surgery. Radioactive iodine is a non-invasive treatment that successfully treats hyperthyroidism 90% of the time, but it can take a few weeks or months before you experience the full benefits. 

Surgery entails the removal of part or all of the thyroid gland. It is the most effective method of dealing with the condition. You will however need to take a medicine that’s used to treat an underactive thyroid, such as levothyroxine, for the rest of your life, to compensate for no longer having a thyroid gland. 

What are thyroid nodules? 

Thyroid nodules are lumps that grow on the thyroid gland itself. This is different from an enlarged thyroid (goitre), which can be triggered for many reasons, including pregnancy or ageing. There are different types of thyroid nodules that present as single growths or in clusters. Single nodules are nearly always benign and can therefore be left untreated. 

Multiple nodules can also often be left untreated, unless they are causing issues with swallowing.

What are colloid nodules? 

Colloid nodules are a benign type of nodule, and can present as single or multiple growths. Thyroid adenomas are also benign, but it is not possible to tell them apart from cancer until a biopsy is taken. For this reason, they will be removed as a matter of course. 

Thyroid cysts can be drained with a needle, but this does not always prove to be entirely effective. In cases where it isn’t successful, surgery may be required.

What is thyroid cancer?

Thyroid cancer is another type of nodule. It’s rare and highly treatable if it’s diagnosed early. Treatment usually requires the thyroid gland, or at least part of it, to be removed. This may be followed by a course of radioactive iodine. It’s also likely that following surgery you will need to take levothyroxine, a synthetic version of the naturally occurring thyroid hormone thyroxine. 

It’s important to note that most lumps and nodules relating to the thyroid are entirely benign. It’s still vital, however, that any lumps you find are investigated as soon as possible. 

If you would like to discuss thyroid medication or any related conditions with a registered clinician, you can speak to one of our clinicians via our online video consultation service, between 9.30am-4.30pm, five days a week. Our clinicians can also issue fit notes and referrals to specialists for treatment, where suitable.  

Page last reviewed:  23/07/2020
Side effects and warnings

What side effects can thyroid medication cause? 

All medications come with some risk of side effects, as is the case for the various thyroid treatments to treat both hyperthyroidism and hypothyroidism. While most people will only experience mild symptoms, or none at all, it’s important to know what the risks are. You can discuss any side effects with your clinician, and refer to the patient information leaflet that comes with your medication for more details. 

The following information relates to the hypothyroidism treatment levothyroxine (synthetic thyroxine) and may not apply to your specific medication. 

If you experience any of the following, discontinue use and seek immediate medical assistance: swelling of the face, tongue, lips and throat, difficulty breathing, severe itching, joint pain, sensitivity to the sun, feeling unwell. 

A small number of patients can experience a reaction to levothyroxine called a thyroid storm. This occurs when there is too much thyroid hormone in the system. Symptoms include a very high temperature, a rapid heart rate, an irregular heartbeat, low blood pressure, heart failure, jaundice, confusion, fits and coma. 

The following side effects have been reported but their frequency is unknown due to how rarely they present. They include: headache, flushing, high temperature, sweating, weight loss, tremor, restlessness, excitability, insomnia, increased pressure around the brain in children, chest pain, pounding or irregular heartbeat, palpitations, diarrhoea, vomiting, muscle cramps, muscle weakness, deformity of the skull in infants, slow growth in children, irregular periods, intolerance to heat and temporary hair loss in children.

Can thyroid medication cause interactions with other treatments? 

It’s important that you inform your prescribing doctor of any other medications you are currently or have recently taken before starting treatment. This includes herbal treatments and supplements. 

The following information relates to levothyroxine. 

Levothyroxine may not be a suitable treatment for you if you are taking any of the following: carbamazepine, phenytoin, primidone, barbiturates, sertraline, antacids, calcium salts, cimetidine, omeprazole, lansoprazole, pantoprazole, sucralfate, cholestyramine, colestipol, polystyrene sulphone resin, rifampicin, imatinib, atenolol, sotalol, oestrogen containing medicines for hormone replacement therapy (HRT) and the contraceptive pill, androgen containing medicines, hydrocortisone, prednisolone, amiodarone, orlistat and ritonavir.

Levothyroxine may affect the way the following treatments work: warfarin, insulin, metformin, amitriptyline, imipramine, dosulepin, adrenaline, phenylephrine, digoxin, phenylbutazone, aspirin, propranolol and ketamine.

Warnings and precautions when using thyroid medication 

It’s essential that you make your prescribing clinician aware of any conditions you have or are prone to. 

The following information relates to levothyroxine.

You should avoid use of this medication if any of the following apply to you: you are allergic to levothyroxine, you have an overactive thyroid gland or any condition that affects your adrenal glands. 

Your doctor may decide this treatment is unsuitable for you if you have any of the following: you have had an under active thyroid for a prolonged period of time, heart problems, angina, coronary artery disease, high blood pressure, diabetes or are over 50 years of age.

It is likely that your doctor will order blood tests to see what dosage of this medication you will need.

Is it safe to take thyroid medication if you are pregnant?

If you are pregnant, think you may be pregnant, are planning on becoming pregnant or are breastfeeding, you will need to inform your doctor. This is particularly important during the first three months of pregnancy.

Page last reviewed:  23/07/2020
Questions and Answers

Can thyroid medication cause any allergic reactions?  

You should tell your doctor about any allergies you have. You can also refer to the patient information leaflet, which lists all of your medication’s ingredients. 

Can thyroid medication affect my ability to drive?

In most cases, thyroid medication should not affect your ability to drive, but there is a risk of low blood pressure occurring, which can lead to dizziness

If you experience any side effects that affect your ability to drive, you should speak to your prescribing doctor and avoid using any heavy machinery. 

Can I buy thyroid medication over the counter? 

No. Thyroid medication is prescription-only treatment. 

Can I buy thyroid medication online?

You can discuss thyroid medication with a GPhC-registered clinician using our online video consultation service, from 9.30am-4.30pm, Monday to Friday. Our clinicians can also provide referrals to specialists for treatment and fit notes, where appropriate.  

Page last reviewed:  23/07/2020

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