Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
FOLLISTIM vs DANAZOL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Follistim (follitropin beta) is a recombinant follicle-stimulating hormone (FSH) that binds to FSH receptors on ovarian granulosa cells and testicular Sertoli cells, stimulating follicular development and steroidogenesis.
Danazol is a synthetic androgen derived from ethisterone that suppresses pituitary-ovarian axis by inhibiting gonadotropin release, leading to decreased estrogen and progesterone levels. It also has weak androgenic and progestational activity.
Ovulation induction in anovulatory women,Controlled ovarian hyperstimulation for assisted reproductive technologies,Spermatogenesis induction in men with hypogonadotropic hypogonadism
FDA: Treatment of endometriosis, fibrocystic breast disease, hereditary angioedema,Off-label: Idiopathic thrombocytopenic purpura, precocious puberty, gynecomastia
Subcutaneous: 75-300 IU once daily for 7-21 days, adjusted based on response. Intramuscular: 75-150 IU once daily for 7-21 days.
300-600 mg orally twice daily; maximum 800 mg/day
The terminal elimination half-life ranges from 16 to 24 hours (mean ~19 hours) following subcutaneous administration. In patients with renal impairment, half-life may be prolonged, necessitating dose adjustment.
Terminal elimination half-life is 4-4.5 hours; clinical context: requires multiple daily dosing to maintain therapeutic levels.
Follitropin beta is metabolized primarily in the liver and kidneys via proteolytic degradation; no specific cytochrome P450 involvement.
Primarily hepatic: undergoes oxidation and conjugation via CYP3A4, with metabolites excreted in urine and feces.
Primarily renal; approximately 70% of the dose is excreted unchanged in urine. A minor fraction (less than 5%) appears in feces via biliary elimination. The remainder is metabolized via hepatic pathways to inactive metabolites.
Primarily hepatic metabolism; approximately 60% excreted in feces, 30% in urine as metabolites.
Approximately 45-50% bound, primarily to albumin and to a lesser extent to alpha-2-macroglobulin.
Highly protein bound: 97-99%, primarily to albumin.
Volume of distribution is approximately 0.3 L/kg (range 0.2-0.4 L/kg), consistent with distribution largely into extracellular fluid.
Approximately 1.5 L/kg; indicates extensive distribution into tissues, exceeding total body water.
Subcutaneous: Approximately 77% (compared to intravenous administration). Intramuscular: approximately 75%. Not available for other routes.
Oral bioavailability is approximately 100% due to extensive absorption, but first-pass metabolism reduces systemic availability to about 70-80%.
No specific guidelines; use caution in severe impairment (e GFR <30 m L/min/1.73m²) due to limited data.
No adjustment required for GFR ≥10 m L/min; avoid use in GFR <10 m L/min due to fluid retention risk
No specific guidelines; use caution in severe hepatic impairment (Child-Pugh C) due to limited data.
Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated
Not FDA-approved for pediatric use; off-label doses: 75-150 IU subcutaneously daily, weight-based titration (1.5-2.25 IU/kg/day) for adolescent males with hypogonadotropic hypogonadism.
2-5 mg/kg/dose orally twice daily; maximum 400 mg/day
Not indicated for geriatric use; no dose adjustment recommended, but limited data in elderly >65 years.
Start at low end of adult dose, titrate cautiously due to increased risk of fluid retention and thromboembolism
Follistim should be used only by physicians experienced in infertility treatment. It may cause ovarian hyperstimulation syndrome (OHSS) and multiple gestations. Serious pulmonary and vascular events have been reported.
Danazol may cause thrombotic events, including pulmonary embolism and thrombophlebitis. It is contraindicated in patients with a history of thrombosis.
Ovarian hyperstimulation syndrome (OHSS) can be severe; monitor ovarian response. Risk of multiple gestation and ectopic pregnancy. Ovarian torsion and adnexal torsion reported. Thromboembolic events. Ovarian enlargement may occur. Patients with porphyria may exacerbate condition.
Hepatotoxicity (monitor LFTs), pseudotumor cerebri (benign intracranial hypertension), androgenic effects (hirsutism, acne, voice deepening), lipid changes (decreased HDL, increased LDL), thromboembolic events, and premature closure of epiphyses in children.
Hypersensitivity to follitropin beta or any component. High levels of FSH indicating primary ovarian failure. Uncontrolled thyroid or adrenal dysfunction. Ovarian cyst or enlargement unrelated to PCOS. Pregnancy. Sex hormone-dependent tumors (e.g., ovarian, breast, uterine, pituitary). Abnormal genital bleeding of undetermined origin.
Pregnancy, lactation, porphyria, severe hepatic/renal/cardiac disease, undiagnosed abnormal genital bleeding, history of thromboembolic disorders, androgen-dependent tumors.
No specific food interactions are documented. Grapefruit and grapefruit juice may potentially affect hormone metabolism, though not established for Follistim; advise patients to maintain a consistent diet and report unusual changes.
Take with food or milk to minimize gastrointestinal irritation. Avoid grapefruit juice as it may alter drug metabolism. Limit alcohol consumption due to increased risk of hepatotoxicity.
FOLLISTIM (follitropin beta) is classified as Pregnancy Category X. There is no indication for use during pregnancy. Animal studies have shown evidence of fetal abnormalities, and use is contraindicated in pregnant women. In the first trimester, exposure may cause fetal harm; however, no well-controlled studies exist. The drug is not used after conception, as its sole indication is for ovulation induction and controlled ovarian stimulation prior to assisted reproductive technologies.
Danazol is contraindicated in pregnancy. First trimester exposure is associated with virilization of female fetus including clitoromegaly, labioscrotal fusion, and urogenital sinus abnormalities. Risk in second and third trimesters is also significant due to androgenic effects; fetal growth restriction and preterm birth may occur. No safe gestational period exists.
FOLLISTIM is not recommended for use during breastfeeding. It is not known whether follitropin beta is excreted in human milk. Given the potential for serious adverse reactions in nursing infants, a decision should be made to discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother. No M/P ratio is available.
Danazol is excreted in human milk; M/P ratio not determined. Potential for adverse effects in breastfed infant (e.g., androgenization). Use is contraindicated during breastfeeding due to risk of virilization and other hormonal effects.
There are no recommended dosing adjustments for FOLLISTIM during pregnancy because the drug is contraindicated and not used in pregnancy. Pregnancy results from treatment, at which point FOLLISTIM is discontinued. No pharmacokinetic changes are studied in pregnancy as it is not administered to pregnant women.
Danazol is contraindicated in pregnancy; no dose adjustment recommendations exist. If inadvertently used during pregnancy, discontinue immediately and monitor for fetal effects. Pharmacokinetic changes in pregnancy are not studied; dose modifications are not applicable due to contraindication.
Follistim (follitropin beta) is a recombinant FSH used for ovulation induction and controlled ovarian stimulation. Monitor estradiol levels and follicular growth via ultrasound to adjust dosing. Risk of ovarian hyperstimulation syndrome (OHSS) increases with high estradiol (>3000 pg/m L) and multiple follicles. Do not use in primary ovarian failure, uncontrolled thyroid/adrenal disorders, or sex hormone-dependent tumors. For subcutaneous administration; rotate injection sites.
Monitor liver function tests; androgenic effects (acne, hirsutism, voice deepening) may occur; use with caution in patients with cardiac or renal impairment; may potentiate warfarin; effective for hereditary angioedema prophylaxis; check pregnancy test before initiation due to teratogenicity.
Follistim is injected subcutaneously exactly as prescribed; do not skip or change dose without talking to your doctor.,You will need regular blood tests and ultrasounds to monitor your response and adjust treatment.,Common side effects include injection site reactions, headache, nausea, and bloating.,Contact your doctor immediately if you experience severe pelvic pain, sudden weight gain, or difficulty breathing, which could indicate ovarian hyperstimulation syndrome (OHSS).,Follistim increases the chance of multiple pregnancy (twins, triplets).,Store vials in the refrigerator, not frozen, and protect from light. Do not use if solution is cloudy or contains particles.
Do not take if pregnant or planning pregnancy; use effective contraception.,Report symptoms of liver toxicity (jaundice, dark urine, abdominal pain) immediately.,Avoid alcohol as it may increase hepatotoxicity risk.,May cause weight gain, acne, or voice changes; report if bothersome.,Take with food to reduce GI upset.,Use sunscreen due to photosensitivity risk.,Do not discontinue abruptly; taper under medical supervision.
No interactions on record
"Formestane, an aromatase inhibitor, reduces estrogen synthesis, while danazol, a synthetic androgen, possesses weak androgenic and anabolic activity. Concomitant use may lead to additive fluid retention due to danazol's mineralocorticoid-like effects and formestane's potential to cause fluid retention through estrogen withdrawal. This can result in peripheral edema, hypertension, or exacerbation of heart failure in susceptible patients."
"Danazol, a synthetic androgen with weak androgenic activity, may reduce the therapeutic efficacy of vildagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor used for glycemic control in type 2 diabetes. The proposed mechanism involves danazol-induced activation of cytochrome P450 enzymes (particularly CYP3A4) and potential upregulation of glucagon counter-regulatory pathways, leading to increased vildagliptin clearance and diminished inhibition of DPP-4. Clinically, this interaction may result in elevated postprandial glucose levels and reduced HbA1c reduction, compromising glycemic management."
"Danazol, an androgenic steroid, can induce hepatic microsomal enzymes, particularly CYP2C9, which accelerates the metabolism of glipizide, a sulfonylurea antidiabetic agent. This increased clearance reduces glipizide's plasma concentrations, diminishing its insulinotropic effect and potentially leading to hyperglycemia and loss of glycemic control in patients with type 2 diabetes mellitus."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about FOLLISTIM vs DANAZOL, answered by our medical review team.
FOLLISTIM is a Gonadotropin that works by Follistim (follitropin beta) is a recombinant follicle-stimulating hormone (FSH) that binds to FSH receptors on ovarian granulosa cells and testicular Sertoli cells, stimulating follicular development and steroidogenesis.. DANAZOL is a Androgen/Antigonadotropin that works by Danazol is a synthetic androgen derived from ethisterone that suppresses pituitary-ovarian axis by inhibiting gonadotropin release, leading to decreased estrogen and progesterone levels. It also has weak androgenic and progestational activity.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between FOLLISTIM and DANAZOL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of FOLLISTIM is: Subcutaneous: 75-300 IU once daily for 7-21 days, adjusted based on response. Intramuscular: 75-150 IU once daily for 7-21 days.. The standard adult dose of DANAZOL is: 300-600 mg orally twice daily; maximum 800 mg/day. 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 FOLLISTIM and DANAZOL 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. FOLLISTIM is classified as Category C. FOLLISTIM (follitropin beta) is classified as Pregnancy Category X. There is no indication for use during pregnancy. Animal studies have shown evidence of fetal abnormalities, and . DANAZOL is classified as Category C. Danazol is contraindicated in pregnancy. First trimester exposure is associated with virilization of female fetus including clitoromegaly, labioscrotal fusion, and urogenital sinus. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.