Thyroid hormone replacement therapy

If you have had surgery to remove your thyroid gland, you will need to take hormone replacement therapy.

Thyroid hormone replacement therapy for thyroid

Surgery can be used to treat papillary and follicular thyroid cancers, medullary thyroid cancer and sometimes anaplastic thyroid cancer. If you have all of your thyroid gland removed, you will need to take thyroid hormone replacement tablets every day for the rest of your life.

You may have to take thyroid hormone replacement tablets even if you had just part of your thyroid gland removed. Thyroxine (T4) is the most common drug given. 

Thyroid hormone tablets have 2 functions:

Keeping your body functioning at the correct speed

Without hormone replacement tablets you would develop the signs and symptoms of hypothyroidism. These include:

  • weight gain
  • tiredness
  • dry skin and hair
  • hair thinning
  • physical and mental slowness
  • constipation
  • feeling cold
  • difficulty concentrating.

Reducing the risk of your cancer coming back

Thyroxine (T4) stops your body making thyroid-stimulating hormone (TSH). TSH helps the thyroid to produce thyroid hormones. But it can also encourage thyroid cancer cells to grow.

If you have had your thyroid gland removed, you will be given thyroxine at a slightly higher dose. This helps to reduce the risk of the cancer coming back after surgery. This is called TSH suppression and is part of your ongoing treatment.

Taking your thyroid hormone tablets

Your doctor will tell you when to start taking hormone replacement tablets.

When you start taking them:

  • it is important to remember to take your thyroid hormone tablets every day
  • you should swallow your tablets with plenty of water
  • take them 30 to 45 minutes before breakfast or your first meal of the day
  • you should take them without any other medications.

Other important information

Calcium supplements may affect the way your body absorbs the thyroid hormone replacement tablets. If you take calcium supplements, you should take them at least 4 hours before or after taking your thyroid hormone tablets.

It is important to check with your pharmacist that the type of thyroid hormone tablets they have given you are exactly as prescribed. This is to try and make sure you continue to take the same brand. If you have any questions about your medication, speak to your doctor, nurse specialist or pharmacist.

Your doctor or nurse will monitor your thyroid hormone levels at a specialist clinic. This helps make sure you are having the correct dose of thyroid hormone tablets. You will have regular blood tests to check the levels of thyroid hormones. It can sometimes take a few months to find the right dose of thyroid hormones for you. You may have some symptoms, such as tiredness, during this time. When the correct dose is found, you should not have any side effects from the tablets. This is because they are simply replacing the hormones that your thyroid gland would have produced naturally.

About our information

  • References

    Below is a sample of the sources used in our thyroid cancer information. If you would like more information about the sources we use, please contact us at

    British Medical Journal. Best Practice Guidelines, Thyroid cancer. 2020.

    European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019.

    National Institute for Health and Care Excellence (NICE). TA535: Lenvatinib and Sorafenib for treating differentiated thyroid cancer after radioactive iodine. 2018. [accessed May 2021].

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
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  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 June 2021
Next review: 01 June 2024

This content is currently being reviewed. New information will be coming soon.

Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.