What is hormonal therapy?

Hormones help control how cells grow and what they do in the body. The hormone oestrogen can encourage some breast cancers to grow. This may also happen with the hormone progesterone.

Hormonal therapy reduces the amount of oestrogen in the body or stops oestrogen attaching to cancer cells. It only works for breast cancer that is oestrogen receptor positive (ER positive). Hormonal therapy is also called endocrine therapy.

Your cancer doctor will advise you to have hormonal therapy to reduce the risk of breast cancer coming back. It also helps reduce the risk of getting a new breast cancer in your other breast.

You usually have hormonal therapy drugs for a number of years. This may be for up to 10 years. You usually start taking them after surgery or chemotherapy.

Hormonal therapy is also used if breast cancer comes back in the same area or spreads to another part of the body (secondary breast cancer).

Types of hormonal therapy


Tamoxifen is an anti-oestrogen drug. It stops oestrogen attaching to breast cancer cells and making them grow. This is the most common type of hormonal therapy used for breast cancer in men.

You take tamoxifen once a day as a tablet.

Aromatase inhibitors

Aromatase inhibitors (AIs) also reduce oestrogen levels. These drugs reduce oestrogen levels in men by stopping male hormones (androgens) being made into oestrogen.

Your cancer doctor may prescribe an AI such as anastrozoleletrozole or exemestane. You take AIs daily as a tablet.

They are only sometimes given to men, and other people assigned male at birth, if they are not able to take tamoxifen.

Goserelin (Zoladex®) injections

Some of the oestrogen in your body is produced by the testicles, not by androgens. Because of this, your cancer doctor may give you another drug called goserelin (Zoladex®) along with an AI. Sometimes you may have it with tamoxifen.

Signals from the pituitary gland in the brain stimulate the testicles to make oestrogen and testosterone. Goserelin blocks these signals and stops the testicles making the hormones. You have goserelin as a slow-release implant. It is injected just under the skin once every 1 to 3 months.

Taking hormonal therapy

Hormonal therapy reduces the risk of breast cancer coming back. It is important to take it for as long as you have been prescribed it. Try to make taking it part of your daily routine so it becomes a habit.

Most people cope well with the side effects of hormonal therapy. Side effects may be more of a problem in the first few months, but they usually get better over time.

If the side effects do not improve or are difficult to cope with, talk to your breast cancer nurse or cancer doctor. They can give you drugs to help and can suggest ways of coping. Sometimes they may suggest changing the time you take the tablet. If you still have problems, they may suggest changing to a different type of hormonal therapy.

Side effects of hormonal therapy

Different hormonal therapy drugs have different side effects. Some of the main side effects include:

  • hot flushes and sweats
  • weight gain
  • joint and muscle pain
  • tiredness
  • sexual effects, including erection problems.

Some types of hormonal therapy can slightly increase the risk of developing a blood clot. We have more information about the side effects of different hormonal therapy drugs.

About our information

  • 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 Dr Rebecca Roylance, Consultant Medical Oncologist and Professor Mike Dixon, Professor of Surgery and Consultant Breast Surgeon.

    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
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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 October 2023
Next review: 01 October 2026
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.