Last updated on RxList: 11/2/2021
Fareston Side Effects Center

What Is Fareston?

Fareston (toremifene citrate) is an estrogen agonist/antagonist that blocks estrogen from reaching cancer cells used to slow the growth of metastatic breast cancer (cancer that has spread from the original tumor). Unlike chemotherapy, Fareston does not actually destroy cancer cells.

What Are Side Effects of Fareston?

Common side effects of Fareston include:

Dosage for Fareston

The dosage of Fareston is 60 mg, once daily, orally. Treatment is generally continued until disease progression is observed.

What Drugs, Substances, or Supplements Interact with Fareston?

Fareston may interact with anticoagulants, thiazide diuretics (water pills), or seizure medications. Tell your doctor all medications and supplements you use.

Fareston During Pregnancy and Breastfeeding

During pregnancy, Fareston should be used only when prescribed. It may harm fetus. If you become pregnant or think you may be pregnant, inform your doctor. Women should use 2 forms of birth control while using this medication. Discuss the use of birth control, and the risks and benefits of this medication with your doctor. It is unknown if this medication passes into breast milk. Because of the possible risk to the infant, breastfeeding is not recommended while using this drug.

Additional Information

Our Fareston (toremifene citrate) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


A lump in the breast is almost always cancer. See Answer
Fareston Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Toremifene can cause a life-threatening heart rhythm disorder. Stop using toremifene and call your doctor at once if you have:

  • fast or pounding heartbeats;
  • fluttering in your chest;
  • sudden dizziness (like you might pass out);
  • shortness of breath; or
  • a seizure.

Also call your doctor at once if you have:

  • pelvic pain, abnormal vaginal bleeding;
  • a slow heart rate, weak pulse, fainting, slow breathing (breathing may stop);
  • blurred vision, tunnel vision, eye pain, or seeing halos around lights;
  • heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating;
  • high calcium levels--confusion, tiredness, nausea, vomiting, loss of appetite, constipation, increased thirst or urination, weight loss;
  • liver problems--loss of appetite, stomach pain (upper right side), dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
  • signs of a blood clot--sudden numbness or weakness (especially on one side of the body), severe headache, slurred speech, problems with vision or balance, chest pain, wheezing, coughing up blood.

Common side effects may include:

  • sweating, hot flashes;
  • nausea; or
  • vaginal discharge.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Fareston (Toremifene)


Breast Cancer Awareness: Symptoms, Diagnosis, and Treatment See Slideshow
Fareston Professional Information


Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

Clinical Trials Experience

Adverse drug reactions are principally due to the antiestrogenic actions of FARESTON and typically occur at the beginning of treatment.

The incidences of the following eight clinical toxicities were prospectively assessed in the North American Study. The incidence reflects the toxicities that were considered by the investigator to be drug related or possibly drug related.

North American Study
n = 221
n = 215
Hot Flashes35%30%
Vaginal Discharge13%16%
Vaginal Bleeding2%4%

Approximately 1% of patients receiving FARESTON (n = 592) in the three controlled studies discontinued treatment as a result of adverse reactions (nausea and vomiting, fatigue, thrombophlebitis, depression, lethargy, anorexia, ischemic attack, arthritis, pulmonary embolism, and myocardial infarction).

Serious adverse reactions occurring in at least 1% of patients receiving FARESTON in the three major trials are listed in the table below.

Three prospective, randomized, controlled clinical studies (North American, Eastern European, and Nordic) were conducted. The patients were randomized to parallel groups receiving FARESTON 60 mg (FAR60) or tamoxifen 20 mg (TAM20) in the North American Study or tamoxifen 40 mg (TAM40) in the Eastern European and Nordic studies. The North American and Eastern European studies also included high-dose toremifene arms of 200 and 240 mg daily, respectively [see Clinical Studies].

Adverse ReactionsNorth AmericanEastern EuropeanNordic
n=221 (%)
n=215 (%)
n=157 (%)
n=149 (%)
n=214 (%)
n=201 (%)
  Cardiac Failure2 (1)1 (<1)-1 (<1)2 (1)3 (1.5)
  Myocardial Infarction2 (1)3 (1.5)1 (<1)2 (1)-1 (<1)
  Arrhythmia----3 (1.5)1 (<1)
  Angina Pectoris--1 (<1)-1 (<1)2 (1)
  Cataracts22 (10)16 (7.5)---5 (3)
  Dry Eyes20 (9)16 (7.5)----
  Abnormal Visual Fields8 (4)10 (5)---1 (<1)
  Corneal Keratopathy4 (2)2 (1)----
  Glaucoma3 (1.5)2 (1)1 (<1)--1 (<1)
  Abnormal Vision/Diplopia----3 (1.5)-
  Pulmonary Embolism4 (2)2 (1)1 (<1)--1 (<1)
  Thrombophlebitis-2 (1)1 (<1)1 (<1)4 (2)3 (1.5)
  Thrombosis-1 (<1)1 (<1)-3 (1.5)4 (2)
  CVA/TIA1 (<1)--1 (<1)4 (2)4 (2)
Elevated Liver Tests**
  AST11 (5)4 (2)30 (19)22 (15)32 (15)35 (17)
  Alkaline Phosphatase41 (19)24 (11)16 (10)13 (9)18 (8)31 (15)
  Bilirubin3 (1.5)4 (2)2 (1)1 (<1)2 (1)3 (1.5)
  Hypercalcemia6 (3)6 (3)1 (<1)---
* Most of the ocular abnormalities were observed in the North American Study in which on-study and biannual ophthalmic examinations were performed. No cases of retinopathy were observed in any arm.
** Elevated defined as follows: North American Study: AST >100 IU/L; alkaline phosphatase >200 IU/L; bilirubin > 2 mg/dL. Eastern European and Nordic studies: AST, alkaline phosphatase, and bilirubin - WHO Grade 1 (1.25 times the upper limit of normal).

Other adverse reactions included leukopenia and thrombocytopenia, skin discoloration or dermatitis, constipation, dyspnea, paresis, tremor, vertigo, pruritus, anorexia, reversible corneal opacity (corneal verticulata), asthenia, alopecia, depression, jaundice, and rigors.

The incidence of AST elevations was greater in the 200 and 240 mg FARESTON dose arms than in the tamoxifen arms. Higher doses of FARESTON were also associated with an increase in nausea.

Approximately 4% of patients were withdrawn for toxicity from the high-dose FARESTON treatment arms. Reasons for withdrawal included hypercalcemia, abnormal liver function tests, and one case each of toxic hepatitis, depression, dizziness, incoordination, ataxia, blurry vision, diffuse dermatitis, and a constellation of symptoms consisting of nausea, sweating, and tremor.

Post-Marketing Experience

The following adverse reactions were identified during post approval use of FARESTON. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Adverse reactions reported during post approval use of FARESTON have been consistent with clinical trial experience. The most frequently reported adverse reactions related to FARESTON use since market introduction include hot flash, sweating, nausea, and vaginal discharge.


Risk of Uterine Malignancy [see WARNINGS AND PRECAUTIONS]

Read the entire FDA prescribing information for Fareston (Toremifene)

© Fareston Patient Information is supplied by Cerner Multum, Inc. and Fareston Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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