Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FARESTON vs CLOMID
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective estrogen receptor modulator (SERM) that competitively binds to estrogen receptors, exerting antiestrogenic effects in breast tissue.
Competitive antagonist of estrogen receptors (ER) in hypothalamus and pituitary, leading to increased gonadotropin-releasing hormone (Gn RH) and subsequent LH and FSH release, stimulating ovulation.
FDA-approved for the treatment of metastatic breast cancer in postmenopausal women with estrogen receptor-positive tumors,Off-label: treatment of advanced breast cancer in premenopausal women in combination with ovarian suppression
Treatment of ovulatory dysfunction in women desiring pregnancy (FDA approved),Off-label: treatment of male infertility (oligospermia)
60 mg orally once daily.
50 mg orally once daily for 5 days, starting on day 5 of the menstrual cycle. May increase to 100 mg daily if no response.
The terminal elimination half-life of toremifene is approximately 5 days (range 2-10 days). The half-life of its main metabolite, N-desmethyltoremifene, is about 11 days. This long half-life supports once-daily dosing.
Terminal half-life is 5–7 days for zuclomiphene (active isomer), with prolonged elimination due to enterohepatic recirculation.
Primarily hepatic via CYP3A4 and CYP1A2; undergoes glucuronidation; active metabolite N-desmethyltoremifene
Hepatic via CYP3A4 and CYP2D6; undergoes enterohepatic circulation; terminal half-life ~5-7 days
FARESTON (toremifene) is extensively metabolized in the liver. Excretion is primarily fecal (approximately 70%) with renal excretion accounting for less than 10% of the dose as unchanged drug and metabolites.
Primarily hepatic metabolism; metabolites excreted in feces (42%) and urine (8% unchanged).
Toremifene is >99% bound to plasma proteins, primarily albumin.
Highly protein bound (>99%), primarily to albumin.
The apparent volume of distribution (Vd) is approximately 580 L (about 8 L/kg for a 70 kg individual), indicating extensive tissue distribution.
Not well-characterized; limited data suggest a large Vd (>100 L) due to extensive tissue distribution.
Oral bioavailability of toremifene is not precisely determined but is estimated to be nearly 100% based on absorption and first-pass metabolism studies.
Oral bioavailability is approximately 50% due to first-pass metabolism.
No dose adjustment required for GFR ≥30 m L/min; insufficient data for GFR <30 m L/min.
No specific adjustment required; use caution in severe impairment (Cr Cl <30 m L/min) as data limited.
Contraindicated in Child-Pugh class C; use with caution in class A or B without specific dose reduction guidelines.
Contraindicated in severe hepatic impairment (Child-Pugh class C). For mild to moderate impairment, no adjustment recommended, but monitor liver function.
Safety and efficacy not established; no recommended dose.
Not indicated for use in children; safety and efficacy not established.
No specific dose adjustment; monitor renal function and electrolyte balance.
Not indicated for postmenopausal women. Use not recommended in elderly due to lack of efficacy in anovulation.
None
None
QT interval prolongation,Hypercalcemia in patients with bone metastases,Endometrial hyperplasia/cancer risk,Thromboembolic events,Ocular toxicity (dose-dependent retinopathy),Tumor flare
Ovarian hyperstimulation syndrome (OHSS),Ovarian enlargement,Visual disturbances (especially with prolonged use),Multiple pregnancy (increased risk),Ectopic pregnancy,Ovarian cancer risk (theoretical, based on prolonged use)
Hypersensitivity to toremifene or any excipients,History of thromboembolic disease,Pre-existing endometrial hyperplasia,Patients with long QT syndrome or concurrent use of QT-prolonging drugs
Pregnancy (Category X),Liver disease or dysfunction,Undiagnosed abnormal vaginal bleeding,Ovarian cyst or enlargement not due to polycystic ovary syndrome,Hypersensitivity to clomiphene or components
Avoid grapefruit and grapefruit juice due to CYP3A4 inhibition, which can increase toremifene levels and risk of adverse effects. No other significant food interactions known. Take with or without food.
No specific food interactions. Avoid grapefruit as it may alter metabolism (theoretical due to CYP3A4 involvement).
Pregnancy Category D. First trimester: Risk of fetal harm, including spontaneous abortion and congenital malformations (e.g., craniofacial, cardiac). Second and third trimesters: Potential for fetal hypothalamic-pituitary-gonadal axis disruption, ambiguous genitalia in female fetuses, and other adverse effects based on animal studies.
Clomiphene citrate is contraindicated in pregnancy. It is associated with an increased risk of fetal malformations, including neural tube defects, specifically when exposure occurs during the first trimester. Second and third trimester risks are not well studied due to contraindication, but theoretical risks include ovarian hyperstimulation syndrome (OHSS) effects on pregnancy.
Not recommended during breastfeeding. Toremifene may be excreted in human milk; M/P ratio not established. Potential for serious adverse reactions in nursing infants, including hormonal disruption.
Safety in breastfeeding is not established. Clomiphene may reduce milk production. The M/P ratio is unknown. It is generally not recommended during breastfeeding.
No established dose adjustments; use contraindicated in pregnancy. Pharmacokinetic changes (increased volume of distribution, altered clearance) may require empirical dose reduction if used inadvertently, but no specific guidelines exist. Avoid use.
No dose adjustments are relevant as clomiphene is contraindicated in pregnancy. Pharmacokinetic changes in pregnancy are not applicable due to contraindication.
FARESTON (toremifene) is a selective estrogen receptor modulator (SERM) used for metastatic breast cancer in postmenopausal women with estrogen receptor-positive tumors. Unlike tamoxifen, toremifene has a longer half-life (about 5 days) and may have a lower risk of thromboembolic events. Monitor liver function tests regularly due to potential hepatotoxicity. Prolongation of QT interval has been reported; avoid in patients with pre-existing QTc prolongation or with other QT-prolonging drugs. Use with caution in patients with endometrial hyperplasia or history of thromboembolic disease.
Monitor ovarian size via ultrasound to reduce risk of ovarian hyperstimulation syndrome (OHSS). Limit course to 3-6 cycles due to increased risk of ovarian tumors. Check pregnancy test before each cycle. Use with caution in liver disease.
Take this medication exactly as prescribed, usually once daily with or without food.,You may experience hot flashes, nausea, or sweating; these are common and usually manageable.,Report any unusual vaginal bleeding, discharge, or pelvic pain to your doctor immediately.,Watch for signs of blood clots such as leg pain/swelling, sudden chest pain, or shortness of breath.,Avoid grapefruit and grapefruit juice while on this medication as they may increase side effects.,Use non-hormonal contraception if you are still able to become pregnant; toremifene can harm a fetus.,Do not stop or change your dose without consulting your healthcare provider.
Take exactly as prescribed, typically 50 mg daily for 5 days starting on day 5 of menstrual cycle.,Report abdominal pain, bloating, nausea, or weight gain (possible OHSS).,Avoid alcohol due to hepatotoxicity risk.,Most pregnancies occur within first 3 cycles; consider alternative after 6 cycles.,May cause visual disturbances; report blurred vision or spots.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about FARESTON vs CLOMID, answered by our medical review team.
FARESTON is a Selective Estrogen Receptor Modulator that works by Selective estrogen receptor modulator (SERM) that competitively binds to estrogen receptors, exerting antiestrogenic effects in breast tissue.. CLOMID is a Selective Estrogen Receptor Modulator that works by Competitive antagonist of estrogen receptors (ER) in hypothalamus and pituitary, leading to increased gonadotropin-releasing hormone (Gn RH) and subsequent LH and FSH release, stimulating ovulation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FARESTON and CLOMID depend on the specific clinical indication. These are both Selective Estrogen Receptor Modulator agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of FARESTON is: 60 mg orally once daily.. The standard adult dose of CLOMID is: 50 mg orally once daily for 5 days, starting on day 5 of the menstrual cycle. May increase to 100 mg daily if no response.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between FARESTON and CLOMID in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. FARESTON is classified as Category C. Pregnancy Category D. First trimester: Risk of fetal harm, including spontaneous abortion and congenital malformations (e.g., craniofacial, cardiac). Second and third trimesters: P. CLOMID is classified as Category C. Clomiphene citrate is contraindicated in pregnancy. It is associated with an increased risk of fetal malformations, including neural tube defects, specifically when exposure occurs. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.