Answer
May 13, 2026 - 08:34 AM
Fareston (toremifene) should not be used by people who:
- Are allergic or hypersensitive to toremifene or any ingredient in the medication.
- Have congenital or acquired QT prolongation/long-QT syndrome.
- Have untreated low potassium (hypokalemia) or low magnesium (hypomagnesemia), because Fareston can cause a potentially dangerous abnormal heart rhythm.
It is also generally not recommended for people with a history of blood-clotting disorders, such as deep-vein thrombosis or pulmonary embolism. Pregnant women should avoid it because it may harm an unborn baby; Fareston is indicated for postmenopausal women.
A prescriber should carefully assess anyone with heart failure, liver problems, uterine or endometrial abnormalities, or who takes medications that prolong the QT interval or strongly affect CYP3A4.
