Toremifene (Fareston®)

Last Modified: September 12, 2012

Pronounced: tore-EM-i-feen
Classification: Antiestrogen

About Toremifene

Toremifene is an antiestrogen or estrogen blocker that works by blocking estrogen receptors in breast tissue. While estrogen may not actually cause breast cancer, it is a necessary component in the growth of breast cancers with estrogen receptor (ER) expression, i.e. ER-positive cancers. With estrogen blocked, the cancer cells that normally proliferate in response to estrogen may not be able to survive.

How to Take Toremifene

Toremifene comes as a tablet to be taken orally (by mouth) around the same time each day. Do not eat grapefruit or drink grapefruit juice while you use Toremifene, as these can affect how your body absorbs the medication.

Possible Side Effects of Toremifene

There are a number of things you can do to manage the side effects of Toremifene. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Hot Flashes or Sweats

There are a few of things you can do to help hot flashes. Several medications have been studied, including clonidine (a blood pressure medication), some low-dose antidepressants (such as venlafaxine and Prozac), and gabapentin. Non-medical recommendations include: keeping well hydrated with 8 glasses of water daily, wearing all-natural fiber clothes, dressing in layers, exercising on a regular basis (generally walking exercise is best), practicing relaxation exercises, and avoiding triggers such as warm rooms, spicy foods, caffeinated beverages, or alcohol.

Nausea and/or Vomiting

There are things you can do to help nausea and vomiting. There are many effective drugs that will prevent, eliminate, or lessen the severity of nausea and vomiting. In addition, dietary adjustments may help. Avoid things that worsen the symptoms, and try antacids (milk of magnesia and calcium tablets, like Tums), saltines, or ginger ale to lessen symptoms.

Blood Clots

Blood clots are a rare side effect that can occur anywhere in the body. They occur most frequently in the calves, and can travel from there to the lungs. Women at risk for developing blood clots include those with a family history of blood clots, heavy smokers, those who have an inactive lifestyle, older women, and those with other predisposing medical problems. Women with any one of these risk factors may want to consider another therapy that does not have this side effect.

Signs of a blood clot in the leg may include any of the following: leg pain, warmth, swelling of one leg more than the other. Signs of a blood clot in the lung could include: fever, shortness of breath that comes on very quickly, racing heart, chest pain (that tends to be worse when you take a deep breath). If you have any of these signs or symptoms of blood clots, you will need to be seen immediately so that you can be treated. Blood thinners can be given. Call your doctor or nurse.


Depression may occur as a result of some of the biological changes occurring in your body and/or your emotional response to some of these changes. Either way, symptoms of depression may include sadness, sleep and appetite changes, as well as a lack of desire to do the activities you once enjoyed. This is very treatable. Please talk to your doctor or nurse if you feel that you are experiencing any of these symptoms.

Tumor Flare

Patients with cancer that has spread to the bone may experience pain or discomfort at the tumor site after starting toremifene, but this should decrease over time and should be managed with pain medication. In addition, patients with bone metastases may develop hypercalcemia (high levels of calcium in the blood) and may require hospitalization to correct this.


While on cancer treatment you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team and see OncoLink’s section on fatigue for helpful tips on dealing with this side effect.

Vaginal Dryness

Vaginal dryness and related painful intercourse is one of the more common side effects of cancer therapy. Vaginal lubricants and moisturizers can help with these concerns. Learn more about specific recommendations for dealing with this side effect. In addition, the desire for sex may decrease during treatment.

Uterine (Endometrial) Cancer

In clinical trials, women taking toremifene for a long period of time were more likely to have endometrial cancer, as compared to women who took placebo. This risk was very small, and doctors believe that the benefits of toremifene outweigh this risk. Women should promptly report any menstrual irregularities, vaginal bleeding, pelvic pressure/pain, or any vaginal discharge, as these may be symptoms of endometrial cancer. An endometrial biopsy should be done to test for cancer if any of these symptoms occur.


Women taking this medication have an increased risk of getting cataracts. You should get a yearly eye exam by an ophthalmologist. Report any vision changes, cloudy or blurry vision, difficulty with night vision, sensitivity to light, fading or yellowing of colors, as these can be symptoms of cataracts.

Other Reported Side Effects

Other side effects reported include: headache, swelling of the hands and/or feet, dizziness, weight gain and insomnia.


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