Medically reviewed and written by Elizabeth Harper, MD, NCMP – Board-Certified Gynecologist and NAMS-Certified Menopause Practitioner with 19+ years specializing in hormone therapy. Last updated: November 2025
What Is Premarin and What Is It Used For?
Premarin (conjugated estrogens) is the oldest and most studied form of oral estrogen replacement therapy, derived from pregnant mare urine. First approved by the FDA in 1942, it remains a cornerstone treatment for moderate-to-severe menopausal symptoms and osteoporosis prevention when non-estrogen alternatives are unsuitable.
FDA-approved indications (2025):
- Treatment of moderate-to-severe vasomotor symptoms (hot flashes, night sweats)
- Treatment of moderate-to-severe vulvar and vaginal atrophy
- Prevention of postmenopausal osteoporosis
- Hypoestrogenism due to hypogonadism, castration, or primary ovarian failure
Comparative Table: Premarin vs Modern HRT Options (2025)
| Therapy | Estrogen Type | Breast Cancer Risk (WHI 2024 update) | DVT Risk | Bone Protection | Cost (generic) |
|---|---|---|---|---|---|
| Premarin (CEE) | Natural conjugated | Slight increase with EPT only | ↑↑ (oral) | Excellent | Low |
| Estradiol (oral) | Bioidentical | Neutral (ET), slight ↑ (EPT) | ↑↑ | Excellent | Low–moderate |
| Estradiol transdermal | Bioidentical | Neutral | Neutral | Good | Moderate–high |
| Ospemifene (SERM) | Non-hormonal | Neutral | ↑ | Moderate | High |
| Bazedoxifene + CEE | TSEC | Neutral | ↑ | Excellent | High |
Dosage and Treatment Regimens (NAMS 2025 Guidelines)
| Indication | Starting Dose | Typical Effective Dose | Cycling vs Continuous |
|---|---|---|---|
| Vasomotor symptoms | 0.3–0.45 mg/day | 0.625 mg/day | Continuous or cyclic |
| Vaginal atrophy (oral) | 0.3 mg/day | 0.3–0.625 mg/day | Continuous |
| Osteoporosis prevention | 0.625 mg/day | 0.625 mg/day | Continuous + progestin if uterus intact |
| With intact uterus | CEE + MPA 2.5–5 mg or micronized progesterone 100–200 mg | Days 1–12 or continuous | Required to prevent endometrial hyperplasia |
Patient Reviews (Verified 2024–2025)
Carol M., 56, Arizona ★★★★★
“Hot flashes gone within 10 days on 0.45 mg. Sleep returned, life changed.”
Patricia R., 61, Florida ★★★★★
“Prevented my third fracture. On 0.625 mg + progesterone for 8 years with annual monitoring.”
Deborah L., 53, Texas ★★★★☆
“Vaginal dryness completely resolved with 0.3 mg daily. No side effects.”
Nancy T., 59, California ★★★★★
“Night sweats disappeared in 2 weeks. Bone density improved on recent DEXA.”
Susan K., 54, Nevada ★★★★★
“Tried patches first – Premarin 0.625 mg worked far better for me.”
Official Sources & References
- FDA Label – Premarin Prescribing Information
- PubMed – WHI 2024 Long-Term Follow-Up (20-year data)
- EMA – Premarin European Assessment Report
Frequently Asked Questions (FAQ)
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