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Faslodex Side Effects

Generic name: fulvestrant

Medically reviewed by Philip Thornton, DipPharm. Last updated on Jan 28, 2023.

Note: This document contains side effect information about fulvestrant. Some dosage forms listed on this page may not apply to the brand name Faslodex.

Applies to fulvestrant: intramuscular solution.

Serious side effects of Faslodex

Along with its needed effects, fulvestrant (the active ingredient contained in Faslodex) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking fulvestrant:

More common

  • Black, tarry stools
  • bleeding gums
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • blood in the urine or stools
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chest pain or tightness
  • chills
  • cloudy urine
  • cough
  • difficulty breathing
  • fainting
  • fever
  • hoarseness
  • irregular heartbeat, recurrent
  • lower back or side pain
  • painful or difficult urination
  • pale skin
  • pinpoint red spots on the skin
  • rapid weight gain
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • tender, swollen glands in the neck
  • tingling of the hands or feet
  • trouble with swallowing
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • unusual weight gain or loss

Less common

  • Anxiety
  • confusion
  • dizziness or lightheadedness
  • fast heartbeat
  • mood or mental changes
  • muscle cramps in the hands, arms, feet, legs, or face
  • numbness and tingling around the mouth, fingertips, or feet
  • pain in the chest, groin, or legs, especially the calves
  • pain, redness, or swelling in the arm or leg
  • seizures
  • severe, sudden headache
  • slurred speech
  • stomach cramps
  • sudden loss of coordination
  • sudden, severe weakness or numbness in the arm or leg
  • tremor
  • vision changes

Incidence not known

  • Dark urine
  • flushing or redness of the skin
  • general feeling of tiredness or weakness
  • headache
  • hives or welts, itching, skin rash
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
  • light-colored stools
  • nausea
  • stomach pain, continuing
  • upper right abdominal pain
  • vaginal bleeding
  • vomiting
  • yellow eyes or skin

Other side effects of Faslodex

Some side effects of fulvestrant may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Back pain
  • bladder pain
  • body aches or pain
  • bone pain
  • change in or loss of taste
  • constipation
  • decreased appetite
  • depression
  • diarrhea
  • difficulty having a bowel movement
  • difficulty with moving
  • dry skin
  • dryness or soreness of the throat
  • feeling of warmth or heat
  • feeling sad or empty
  • frequent urge to urinate
  • general feeling of discomfort or illness
  • hair loss or thinning of hair
  • irritability
  • joint pain
  • lack or loss of appetite
  • lack or loss of strength
  • loss of interest or pleasure
  • muscle aches and pains
  • muscle stiffness
  • pain at the injection site
  • pain in the arms or legs
  • pelvic pain
  • shivering
  • stomach pain
  • sudden sweating
  • trouble concentrating
  • voice changes
  • weight loss

Less common

  • Dry eye
  • dry mouth
  • increased tearing
  • nervousness
  • swelling or redness in the joints

Incidence not known

  • Feeling of constant movement of self or surroundings
  • sensation of spinning

For Healthcare Professionals

Applies to fulvestrant: intramuscular solution.


Very common (10% or more): Nausea (up to 34%), stomatitis (up to 28%), diarrhea (up to 24%), vomiting (up to 19%), abdominal pain (up to 12%)

Common (1% to 10%): Constipation[Ref]


Very common (10% or more): Neutropenia (up to 83%), leukopenia (up to 53%), anemia (up to 30%), thrombocytopenia (up to 23%)

Common (1% to 10%): Reduced platelet count

Uncommon (0.1% to 1%): Leukorrhea, febrile neutropenia[Ref]


Very common (10% or more): Vasodilation(up to 18%), hot flushes

Common (1% to 10%): Venous thromboembolism[Ref]


Very common (10% or more): Bone pain (up to 16%), muscle pain, joint pain

Common (1% to 10%): Back pain, pain in extremity[Ref]

Nervous system

Very common (10% or more): Headache (up to 15%)

Common (1% to 10%): Sciatica, peripheral neuropathy, dysgeusia, dizziness, paresthesia

Uncommon (0.1% to 1%): Neuralgia[Ref]


Very common (10% or more): Pharyngitis (up to 16%), dyspnea (up to 15%)

Common (1% to 10%): Epistaxis, cough, chest pain[Ref]


Very common (10% or more): Pelvic Pain (up to 10%)

Common (1% to 10%): Urinary tract infection, vaginal hemorrhage

Uncommon (0.1% to 1%): Vaginal moniliasis[Ref]


Very common (10% or more): Alopecia (up to 18%), rash (up to 17%)

Common (1% to 10%): Dry skin, sweating, pruritus[Ref]


Very common (10% or more): Hypersensitivity reactions

Uncommon (0.1% to 1%): Anaphylaxis[Ref]


Very common (10% or more): Elevated hepatic enzymes (ALT, AST, ALP)

Common (1% to 10%): Elevated bilirubin

Uncommon (0.1% to 1%): Hepatic failure, hepatitis, elevated gamma-GT[Ref]


Very common (10% or more): Infections (up to 47%)

Common (1% to 10%): Influenza syndrome[Ref]


Very common (10% or more): Injection site pain (up to 12%), injection site reaction

Common (1% to 10%):

Uncommon (0.1% to 1%): Injection site hemorrhage, injection site hematoma[Ref]


Common (1% to 10%): Increased lacrimation, blurred vision, dry eye[Ref]


Very common (10% or more): Anorexia (up to 16%)

Common (1% to 10%): Peripheral edema[Ref]


Common (1% to 10%): Insomnia, depression, anxiety[Ref]


Very common (10% or more): Fatigue (up to 41%), pain (up to 19%), pyrexia (up to 13%)

Common (1% to 10%): Asthenia[Ref]

Frequently asked questions


1. Product Information. Faslodex (fulvestrant). Astra-Zeneca Pharmaceuticals. 2002.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.