Fulvestrant (Faslodex®)
What is fulvestrant (Faslodex®)?
Fulvestrant is a hormonal therapy drug. It is sometimes called Faslodex® which is a brand of fulvestrant. It is used to treat breast cancer.
You may have fulvestrant on its own or with other drugs. If the cancer is HER2 negative, you may have it with one of the following targeted therapy drugs:
It is best to read this information with our general information about hormonal therapy and the type of cancer you have.
Your cancer team will talk to you about this treatment and its possible side effects before you agree (consent) to have treatment.
More information about this treatment
This information is correct at time of publishing. But sometimes the types of cancer this treatment is used for, or treatment side effects, may change between revision dates.
You can talk to your cancer team if you want more detailed information about this treatment. Or visit the electronic Medicines Compendium (eMC) website, which has patient information leaflets (PIL) for individual drugs.
How fulvestrant works
Hormones are chemicals that our bodies make. They act as messengers and help control how cells and organs work. Hormonal therapy drugs change how hormones are made or work in the body.
The hormone oestrogen can encourage some breast cancers to grow. These breast cancers have receptors (proteins) on the cancer cells which allow oestrogen to attach to the cell.
Breast cancer that has receptors for oestrogen is called oestrogen receptor positive or ER positive breast cancer. The term ER is used because the American spelling of oestrogen is estrogen.
Fulvestrant blocks the receptors and stops oestrogen reaching the cancer cells. This slows down the cancer or stops it from growing. Fulvestrant also reduces the number of receptors on the breast cancer cells.
How fulvestrant is given
During your treatment, you will meet someone from your cancer team, such as a:
- cancer doctor
- specialist nurse
- specialist pharmacist.
This is who we mean when we mention doctor, nurse or pharmacist in this information.
Your nurse or doctor will talk to you about your treatment plan. You usually have fulvestrant for as long as it helping to control the cancer.
You have fulvestrant as an injection into a muscle (intramuscular injection). For each dose you have 2 injections, 1 in each buttock. Each injection takes 1 to 2 minutes.
You have the first 3 doses 2 weeks apart. After that you have the injections once a month.
You may have the injections at the hospital or at your GP surgery. Your GP, specialist cancer nurse or practice nurse will give you the injection. If you are not able to visit the hospital or GP surgery, a district nurse may give you the injections at home.
If there is a delay in giving the injections by 1 or 2 days, this should not affect how well the treatment works. But it is important to make sure you have your injections every month as prescribed.
Tell your doctor or nurse if you are taking any medicines to thin your blood (anticoagulants). These may increase bruising.
Injection site
The skin in the area that was injected may become:
- painful
- swollen
- red, if you have white skin
- darker, if you have black or brown skin.
If this happens, let your doctor know. Painkillers may help.
About side effects
We explain the most common side effects of this treatment here. We also include some that are less common.
You may get some of the side effects we mention, but you are unlikely to get all of them. And you may have some side effects, including rarer ones, that we have not listed here.
Other cancer treatments may cause different side effects. If you are also having other cancer treatment, you may have other side effects.
When you have this treatment, you will have regular appointments with a doctor, nurse or pharmacist. Always tell them about any side effects you have. They can give you:
- drugs to help control most side effects
- advice about managing side effects.
Most side effects can be managed. But sometimes side effects are harder to control. It is important not to stop taking hormonal therapy without telling your doctor. If side effects cannot be managed, your doctor may suggest a different type of hormonal therapy.
Serious and life-threatening side effects
Some cancer treatments can cause serious side effects. Sometimes, these may be life-threatening. Your doctor, nurse or pharmacist can explain the risk of these side effects to you.
Contact the hospital
Your doctor, nurse or pharmacist will give you 24-hour contact numbers for the hospital. If you feel unwell or need advice, you can call at any time of the day or night. Save these numbers in your phone or keep them somewhere safe.
Very common side effects
These side effects happen to 10 or more people in every 100 people (10% or more) who have this treatment.
Allergic reaction
This treatment might cause an allergic reaction. But this is not common. Signs of a reaction can include:
- a skin rash or itching
- feeling breathless or wheezy
- swelling of your face, mouth or throat.
If you feel unwell or have any of these signs, contact the hospital straight away on the 24-hour number. Do not take any more of this treatment until you have checked with them.
Always call 999 if swelling happens suddenly or you are struggling to breathe.
Hot flushes and sweats
Hot flushes are a common side effect of this treatment. During a flush, your neck and face may feel warm. If you have white skin, your skin may look red. If you have black or brown skin, your skin colour may deepen. Flushes can last up to 5 minutes. You might also have sweats or feel anxious or irritable during a flush.
Here are some things you can do to reduce the effects of hot flushes:
- Wear natural fabrics, such as cotton.
- Wear layers so you can remove clothes as needed.
- Use cotton sheets and layers of bedding you can remove.
- Try cooling pads or pillows to keep you cool.
- Keep rooms cool or use a fan.
- Have cold drinks and avoid caffeine and alcohol.
You might have fewer hot flushes as your body adjusts to this treatment. You could try therapies to help you cope with hot flushes, such as:
- talking therapies like cognitive behaviour therapy (CBT)
- controlled breathing exercises
- yoga
- acupuncture.
If they do not improve, talk to your doctor. Certain drugs can help to improve hot flushes.
Flushes usually stop a few months after treatment ends. But some people continue to have them.
Feeling sick
You may feel sick, but this is usually mild. If you feel sick, tell your doctor or nurse. They can give you anti-sickness drugs to help.
Muscle or joint pain
You may get pain in your muscles or joints. If this happens, tell your doctor or nurse. They can give you advice and painkillers or other drugs to help. Being physically active and keeping to a healthy weight may help with the pain. It can keep your joints flexible and reduce stress on them. If the pain does not get better, tell your doctor or nurse. They may talk to you about changing to a different hormonal drug.
Skin changes
This treatment can affect your skin. It may cause a rash, which may be itchy. Your doctor or nurse can tell you what to expect. If your skin feels dry, try using soap-free cleansers and unperfumed moisturising cream every day.
Always tell your doctor or nurse about any skin changes. They can give you advice and may prescribe creams or medicines to help. Changes to your skin usually improve when treatment ends.
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.
Feeling tired (fatigue)
Feeling tired is a common side effect. Try to pace yourself and plan your day so you have time to rest between activities.
Being physically active can help to manage tiredness and give you more energy. It also:
- helps you sleep better
- reduces stress
- improves your bone health.
If you feel sleepy, do not drive or operate machinery.
Other side effects
These side effects happen to less than 10 in 100 people (less than 10%) who have this treatment. Some of them are much rarer than this but they are still important to know about. Rare means a side effect that happens to less than 1 in 1,000 people (less than 0.1%).
Urine infection
Fulvestrant can make you more likely to get a urine infection. Let your doctor, nurse or pharmacist know if:
- you have pain when you pass urine (pee)
- you need to pass urine more often than usual
- your urine is cloudy or smelly.
Your doctor, nurse or pharmacist may test your urine. If you have an infection, you may need antibiotics.
Headaches
This treatment may cause headaches. If you have headaches, tell your doctor, nurse or pharmacist. They can give you advice about painkillers that may help. Tell them if the headache does not get better, or gets worse.
Diarrhoea
This treatment may cause diarrhoea. Diarrhoea means passing more stools (poo) than is normal for you, or having watery or loose stools. You may also have stomach cramps. If you have a stoma, it may be more active than usual.
If you are passing loose stools 3 or more times a day and this is not normal for you, contact the hospital as soon as possible on the 24-hour number. Follow the advice they give you about:
- taking anti-diarrhoea medicines
- drinking enough fluids to keep you hydrated and to replace lost salts and minerals
- any changes to your diet that might help.
They might also ask you for a specimen of your stool to check for infection.
Vaginal dryness, discharge or bleeding
This treatment can cause vaginal dryness. Non-hormonal creams, gels or lubricants can help with vaginal dryness and any discomfort during sex. You can buy these from a chemist. Or your doctor can prescribe them.
It can also cause a thick, whitish vaginal discharge and thrush. Tell your doctor, nurse or pharmacist if you have discharge, soreness or itching. You might have slight vaginal bleeding for a short while:
- when you start treatment
- if you change from 1 hormonal treatment to another.
Vaginal dryness can also cause bleeding. Tell your doctor or nurse if you have any vaginal bleeding, especially if it lasts for more than a few days.
Bruising and bleeding
This treatment can reduce the number of platelets in your blood. Platelets are cells that help the blood to clot.
If the number of platelets is low, you may bruise or bleed easily. You may have:
- nosebleeds
- bleeding gums
- heavy periods
- blood in your urine (pee) or stools (poo)
- tiny red, brown or purple spots that may look like a rash – these spots can be harder to see if you have black or brown skin.
If you have any unexplained bruising or bleeding, contact the hospital straight away on the 24-hour number. You may need a drip to give you extra platelets. This is called a platelet transfusion.
Loss of appetite
This treatment can affect your appetite. Don’t worry if you do not eat much for 1 or 2 days. But if your appetite does not come back after a few days, or if you are losing weight, tell your doctor, nurse or pharmacist. They can give you advice. They may give you food or drink supplements. Or they may suggest changes to your diet or eating habits to help.
Numb or tingling hands or feet (peripheral neuropathy)
This treatment may affect the nerves in your fingers and toes. This can cause numbness, tingling or pain in your hands or feet. This is called peripheral neuropathy. You might find it hard to do fiddly tasks such as fastening buttons or tying shoelaces.
If you have these symptoms, always tell your doctor, nurse or pharmacist. They sometimes need to change the drug or the dose of the drug. The symptoms usually improve slowly after treatment ends. But for some people they continue and are a long-term side effect of treatment.
Other important information
Blood clot risk
Cancer and some cancer treatments can increase the risk of a blood clot. Contact the hospital straight away on the 24-hour number if you have any of these symptoms during or after treatment:
- throbbing pain or swelling in a leg or arm
- reddening of the skin in the area – if you have black or brown skin, this can be harder to notice, but the skin might become darker
- suddenly feeling breathless or coughing.
Always call 999 if you have:
- chest pain
- difficulty breathing.
A blood clot is serious, but it can be treated with drugs called anticoagulants. These thin the blood. Your doctor, nurse or pharmacist can give you more information about preventing and treating blood clots.
Alcohol
Some preparations of this treatment contain alcohol. If having alcohol is a problem for you, tell your doctor, nurse or pharmacist. Your blood alcohol level may be above the legal limit after you have the treatment. Do not drive or operate machinery for a few hours after having this treatment, even if you feel okay.
Other medicines
Some medicines can affect how this treatment works or be harmful while you are having it. Always tell your cancer doctor, nurse or pharmacist about any drugs you are taking or planning to take, such as:
- medicines you have been prescribed
- medicines you buy in a shop, pharmacy or online
- vitamins or supplements
- herbal drugs and complementary or homeopathic therapies
- recreational drugs – for example, cannabis.
Contraception
Your doctor, nurse or pharmacist will advise you not to get pregnant or make someone pregnant while having this treatment and for some time afterwards. The drugs may harm a developing baby. It is important to use contraception to prevent pregnancy. Follow their advice about:
- what types of contraception to use
- how long after treatment you should continue to use contraception.
Breastfeeding
You are advised not to breastfeed while having this treatment, or for some time after treatment ends. This is because the drugs could be passed to the baby through breast milk.
Your doctor, nurse or pharmacist can give you more information.
Fertility
Some cancer drugs can affect whether you can get pregnant or make someone pregnant. If you are worried about this, it is important to talk with your doctor before you start treatment.
Medical and dental treatment
If you need medical treatment for any reason other than cancer, always tell the healthcare professional that you are having cancer treatment. Give them the contact details for your cancer doctor or cancer team so they can ask for advice.
If you have appointments with a dentist, always tell them you are having cancer treatment. Talk to your cancer team before you have any dental treatment.
About our information
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.
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References
Visit the electronic Medicines Compendium (eMC) to download a Patient Information Leaflet (PIL) for more detailed information. The leaflet lists all known side effects.
Date reviewed
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.
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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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.