Toremifene (Fareston®)

Toremifene is a hormonal therapy drug used to treat breast cancer. It’s best to read this with our general information about breast cancer.

You have toremifene as tablets. You usually have it as an outpatient. Your cancer doctor or nurse will tell you how long you take it for.

Like all hormonal therapy drugs, toremifene can cause side effects. Some of these can be serious so it’s important to read the detailed information below. How hormonal therapy affects people varies from person to person. It’s important to read about the side effects so that you know what to expect. Your doctor or nurse can talk to you more about this and give you advice on how to manage side effects.

Tell your doctor or nurse straight away if you feel unwell or have severe side effects, including any we don’t mention here. If you need to see a health professional for any reason other than cancer, always tell them that you are having this treatment.

How toremifene works

Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs. Hormonal therapies are drugs that interfere with the way hormones are made or how they work in the body.

Many breast cancers rely on the hormone oestrogen to grow. This is called oestrogen-receptor positive (ER positive) breast cancer. Toremifene blocks oestrogen from reaching the cancer cells. This means the cancer may grow more slowly or stop growing altogether.


When toremifene is given

Toremifene may be used to treat ER positive breast cancer in women who have been through the menopause. It is used to treat breast cancer that has spread to other areas of the body (secondary or advanced breast cancer).

Your cancer doctor or nurse will explain how long you should take toremifene for. You usually have it for as long as it is effective in controlling the cancer.


Taking your toremifene tablets

You take toremifene as a tablet, usually once a day. You can take it with or without food. You take it at the same time each day, morning or evening. Always take your tablets exactly as your nurse or pharmacist has explained. This is important to make sure they work as well as possible for you.

Do not stop taking any of your tablets unless your doctor tells you to. Here are some important things to remember:

  • If you forget to take your tablets, just take your next dose at your usual time. Don’t take a double dose.
  • Keep tablets in the original package and at room temperature, away from heat and direct sunlight.
  • Keep them safe and out of the sight and reach of children.
  • Get a new prescription before you run out of tablets, and make sure you have plenty for holidays.
  • Return any remaining tablets to the pharmacist if your treatment is stopped.


Possible side effects of toremifene

We explain the most common side effects of toremifene here. We also include some rarer side effects. You may get some of the side effects we mention, but you are very unlikely to get all of them. If you are having other drugs as well, you may have some side effects that we don’t list here.

You will see a doctor or nurse regularly while you have this treatment. Always tell your doctor or nurse about the side effects you have. They can prescribe drugs to help control them and give you advice about managing them. Don’t stop taking toremifene without talking to your doctor first.

More information about this drug

We’re not able to list every side effect for this treatment here, particularly the rarer ones. For more detailed information you can visit the electronic Medicines Compendium (eMC).

Hot flushes and sweats

These are common side effects. They may gradually lessen over the first few months, but some women continue to have them for as long as they take toremifene.

Cutting down on nicotine, alcohol and hot drinks containing caffeine, such as tea and coffee, can help. Dress in layers, so you can remove clothes as needed. Natural fabrics, such as cotton, may feel more comfortable.

If hot flushes are troublesome, tell your doctor. Low doses of certain anti-depressant drugs can help to reduce flushes.

You can read more about treatments for menopausal symptoms like hot flushes in our section on breast cancer and menopausal symptoms.

Vaginal discharge

Some women have a vaginal discharge or bleeding when on this treatment. It is always important to tell your doctor or nurse if you notice any unusual bleeding from your vagina.

Feeling sick

You may feel sick at times when you start taking toremifene. This often lessens or goes away after a few weeks.

Tiredness

You may feel more tired than usual. Try to balance rest periods with some physical activity such as short walks. This can help you to feel less tired.

Fluid build-up (oedema)

Some women may have swollen ankles or fingers when taking toremifene. This is caused by a build up of fluid, which is called oedema. It is usually mild. If you notice any swelling or puffiness, ask your nurse or doctor for advice.

Effects on the skin

Toremifene can cause a rash or itchy skin. These effects are usually mild. Tell your doctor if you develop a rash or itching. They may prescribe drugs or creams to help.

Dizziness or changes in vision

Some women may feel dizzy. Rarely, they may have blurred vision or changes in their eyesight. These side effects may be worse if you take toremifene with alcohol. Always tell your doctor or nurse if you have any of these side effects. Don’t drive or operate machinery if you have them.

Changes in mood

You may have mood changes or feel low or depressed when taking toremifene. Talk to your nurse or doctor if this happens. They can suggest ways to help with this.


Less common side effects of toremifene

Blood clots (thrombosis)

This is rare. Signs of a blood clot include pain, warmth, swelling or tenderness in an arm or leg, or chest pain. Tell your doctor straight away if you have any of these signs. Toremifene isn't usually given to people who have had a blood clot in the past.

Increased risk of womb cancer

Women who have been through menopause and take toremifene over a long period of time have a slightly increased risk of cancer of the womb. But the benefits of taking toremifene outweigh this risk. Your doctor may arrange for you to have yearly tests to check your womb. If womb cancer is found, early treatment is very successful.

Always tell your doctor if you have vaginal bleeding after the menopause so they can check for the cause. It can be an early sign of womb cancer, although it is usually caused by conditions other than cancer.

Changes in heart rhythm

A small number of people develop changes in their heartbeat when on this drug. Tell your doctors if you have ever had heart rhythm changes or any other problems with your heart. You should also tell them if you’re taking any medicines for your heart. If you notice a change in your heartbeat such as irregular rhythms, it is important to tell your doctor. They may do a test to check your heart rhythm (ECG).

Always let your doctor or nurse know about any side effects you have. These can usually be controlled or improved.


Other information about toremifene

Other medicines

Toremifene can interact with other drugs. Tell your doctor about any medicines you are taking, including ones you can buy for yourself. This includes vitamin supplements, complementary therapies and herbal drugs.

Problems with lactose

Toremifene tablets contain a type of sugar called lactose. If you have been told by a doctor that you cannot digest some sugars or are lactose intolerant, talk to your doctor before taking this drug.

Medical or dental treatment

If you need to go into hospital for any reason, always tell the doctors and nurses that you are taking toremifene. Explain you are taking hormonal therapy and that no one should stop or restart it without checking with your cancer doctor first. Tell them the name of your cancer doctor so they can ask for advice.

Always tell your dentist you are taking toremifene before having any dental treatment.