How does this medication work? What will it do for me?

Fulvestrant belongs to the group of cancer-fighting medications known as antineoplastics, and specifically to the type of antineoplastics known as anti-estrogens. It treats certain types of breast cancer by blocking the effects of the hormone estrogen in the body. This prevents the growth of the types of breast cancer cells that require estrogen for growth and survival.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Each mL of clear, colourless to yellow, viscous liquid for injection contains fulvestrant 50 mg. Nonmedicinal ingredients: benzyl alcohol, benzyl benzoate, castor oil, and ethanol 96%.

How should I use this medication?

The recommended dose of fulvestrant is 500 mg given as an injection into the muscle of the buttocks, every 2 weeks for 3 doses. After this, 500 mg should be given every 28 days.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Fulvestrant is only available as an injection that is given into the muscle of the buttocks. Some people choose to learn how to self-administer the medication. Your doctor or health care professional will show you exactly how to prepare the injection site and how to inject the medication. If this is the case, make sure you understand exactly how it is to be injected as instructed by your doctor or nurse. Read the patient information carefully and ask your doctor or health care professional any question you may have.

Fulvestrant comes in pre-filled syringes, ready for injection. The medication should be a clear, colourless-to-yellow, thick liquid. Do not use the medication if it appears cloudy or discoloured, or if there are particles floating in it.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

If you miss an appointment to receive fulvestrant, contact your doctor as soon as possible to reschedule your appointment.

Fulvestrant should be refrigerated in its original package. Keep out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use fulvestrant if you:

  • are allergic to fulvestrant or any ingredients of the medication
  • are breast-feeding
  • are pregnant

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • constipation
  • diarrhea
  • fatigue
  • headache
  • hot flashes
  • loss of appetite
  • mild pain, redness, or swelling around the area of injection
  • nausea
  • rash
  • vomiting
  • weakness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • abdominal pain
  • back pain
  • burning, prickling, or tingling sensations in the hands or feet
  • flu-like symptoms (headache, chills, muscle or joint pain, tiredness)
  • hoarseness
  • increased blood pressure
  • joint pain
  • muscle pain
  • nasal congestion
  • signs of a bladder infection (frequent urination, pain or burning feeling when urinating, smelly urine)
  • signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
  • swelling of the hands, feet, or ankles (if you are not having difficulty breathing)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • chest pain
  • signs of a serious allergic reaction (abdominal cramps, hives, difficulty breathing, nausea and vomiting, swelling of the face, tongue, or throat)
  • swelling of the hands, feet, or ankles (if you are having difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.


October 18, 2016

Health Canada has issued new restrictions concerning the use of Faslodex (fulvestrant). To read the full Health Canada Advisory, visit Health Canada's web site at

Drowsiness/reduced alertness: This medication may cause weakness or fatigue. Do not drive, operate machinery, or perform other potentially hazardous tasks until you have determined how this medication affects you.

Kidney function: If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver disease: The liver changes fulvestrant into components of the drug that are active in the body. If your liver is not working properly, fulvestrant builds up in the body and may lead to increased side effects.

If you have reduced liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Red blood cells: Fulvestrant may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Risk of bleeding: Because this medication is given by injection, caution should be used by people at an increased risk of bleeding, such as those taking blood thinners (e.g., warfarin) or those with medical conditions that can cause bleeding.

Pregnancy: Fulvestrant can cause harm to the unborn baby if it is used during pregnancy. This medication should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known whether fulvestrant passes into breast milk, however it has the potential to cause serious side effects in infants who are exposed to it. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

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