What is toremifene (Fareston®)?

Toremifene (Fareston®) is a hormonal therapy drug used to treat breast cancer. It can be given alone or with other types of treatment. It is best to read this information with our general information about hormonal therapies and breast cancer. 

Your doctor will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment. 
 

How toremifene works

Hormones are chemicals that our bodies make. Hormones act as messengers and help control how cells and organs work. Hormonal therapies are drugs that change 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.

Taking toremifene tablets

Toremifene comes as tablets you can take at home. Your nurse or doctor will talk to you about your treatment plan.

Always take the tablets exactly as explained. This is important to make sure they work as well as possible for you.

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.

If you forget to take the tablet, you should take the next tablet as usual. Do not take a double dose. If you have missed more than one dose, tell your doctor or nurse.

Other things to remember about your tablets:

  • Keep them 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.
  • If your treatment is stopped, return any unused tablets to the pharmacist.

Your nurse or pharmacist may also give you other medicines to take home. Take all your medicines exactly as they have been explained to you. Do not stop taking any of your medicines unless your doctor tells you to.

Side effects of toremifene

We explain the most common side effects of this treatment here. We also include some less common side effects.

You may get some of the side effects we mention, but you are unlikely to get all of them. If you are also having treatment with other cancer drugs, you may have some side effects that we have not listed here. Always tell your doctor, nurse or pharmacist about any side effects you have.

Your doctor can give you drugs to help control some side effects. It is important to take them exactly as your nurse or pharmacist explains. This means they will be more likely to work for you. Your nurse will give you advice about managing your side effects. After your treatment is over, most side effects start to improve.

Some cancer treatments can cause severe side effects. Rarely, these may be life-threatening. Your cancer doctor or nurse can explain the risk of these side effects to you.

Your nurse will give you telephone numbers for the hospital. If you feel unwell or need advice, you can call them at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.

We cannot list every side effect for this treatment. There are some rare side effects that are not listed. You can visit the electronic Medicines Compendium (eMC) for more detailed information.

Common side effects of toremifene

Hot flushes and sweats

Hot flushes are a common side effect of this treatment. During a flush, your neck and face may feel warm and look red. Flushes may last from a few seconds up to 10 minutes. You may have sweats and then feel cold and clammy. Some people feel anxious or irritable during a hot flush.

There are things you can do to try to reduce flushes:

  • Wear clothes made from natural fabrics, such as cotton.
  • Wear layers of clothes that you can remove if you feel hot.
  • Use cotton bed sheets and have layers of bedding that you can remove if you feel hot.
  • Keep room temperatures cool or use a fan.
  • Have cold drinks rather than hot ones. Try to avoid drinks with caffeine in them.

You may have fewer hot flushes and sweats as your body adjusts to hormonal treatment. Or your doctor can prescribe drugs to help. Flushes and sweats usually stop a few months after treatment finishes, but some people continue to have them.

We have more information about coping with hot flushes. Women can read more about coping with hot flushes in our information about managing menopausal symptoms.

Vaginal discharge

Some women have a white or yellowish vaginal discharge or bleeding when on this treatment. If bleeding continues for more than a few days, tell your doctor or nurse.

Feeling sick

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

Fluid build-up (oedema)

You may find your ankles or fingers become swollen 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.

Tiredness

Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest. Gentle exercise, like short walks, can give you more energy. If you feel sleepy, do not drive or operate machinery.

You may have difficulty sleeping when taking this treatment. Talk to your doctor or nurse if you do.

Skin changes

This treatment may affect your skin. It may cause a rash, which might be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using an unperfumed moisturising cream every day.

Always tell your doctor or nurse about any changes to your skin. They can give you advice and may prescribe creams or medicines to help. Skin changes usually improve when treatment finishes.

Dizziness or changes in vision

This treatment may make you feel dizzy. Rarely, it causes blurred vision or changes in eyesight. Always tell your doctor or nurse if you have any of these side effects. Do not drive or operate machinery if you have them.

Mood changes

You may have some mood changes during this treatment. You may feel low or depressed. Let your doctor or nurse know if you notice any changes.

Less common side effects of toremifene

Weight gain

You may gain weight when you are having this treatment. Eating healthily and being active can help you keep to a healthy weight. Your doctor, nurse or a dietitian can give you more advice.

Headaches

This treatment may cause headaches. If this happens, tell your doctor or nurse. They can give you painkillers.

Blood clot risk

Cancer and some cancer treatments can increase the risk of a blood clot. Symptoms of a blood clot include:

  • pain, redness or swelling in a leg or arm
  • breathlessness
  • chest pain.

If you have any of these symptoms, contact a doctor straight away.

A blood clot is serious, but can be treated with drugs that thin the blood. Your doctor or nurse can give you more information.

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.

Effects on the heart

This treatment can affect the way your heart works. Your doctor may do tests to see how well your heart is working. You may have these tests before, during, and sometimes after treatment.

Contact a doctor straight away if you:

  • have pain or tightness in your chest
  • feel breathless or dizzy
  • feel your heart is beating too fast or too slowly.

Other conditions can cause these symptoms. But it is important to get them checked by a doctor.

Effects on the liver

This treatment may affect how your liver works. This is usually mild. You will have blood tests to check how well your liver is working.

Other information about toremifene

Other medicines

Some medicines can affect how this treatment works or be harmful when you are having it. Always tell your cancer doctor about any drugs you are taking or planning to take, such as:

  • medicines you have been prescribed
  • medicines you buy in a shop or chemist
  • vitamins, herbal drugs and complementary therapies.

Tell other doctors, pharmacists or dentists who prescribe or give you medicines that you are having this cancer treatment.

You can visit the electronic Medicines Compendium (eMC) for more detailed information about your treatment.

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 and dental treatment

If you need medical treatment for any reason other than cancer, always tell the doctors and nurses that you are having cancer treatment. Give them the contact details for your cancer doctor so they can ask for advice.

If you think you need dental treatment, talk to your cancer doctor or nurse. Always tell your dentist you are having cancer treatment.