Premarin (conjugated estrogens)
conjugated estrogens, USP · tablet · brand (Pfizer)
The finding
HORSE
Premarin's active ingredient is made from the urine of pregnant mares (equine). This is the medicine itself, not an added ingredient, and there is no generic version.
Do not stop hormone therapy on your own. Bring this to a scholar you trust; scholars have addressed animal-derived medicines under necessity.
We tell you the source. Your scholar decides what's permissible, and your doctor and pharmacist decide your care.
What this means
The name Premarin comes from pregnant mare urine. Estrogens made by synthesis from plant sterols, for example estradiol, are different medicines, prescribed and dosed differently. Talk to your doctor about your treatment.
What to do
- Keep taking it as prescribed, and do not change or stop it without your prescriber.
- Tell your doctor the source matters to you, and ask whether an estrogen made by synthesis from plant sterols is appropriate for you.
- Bring this to a scholar you trust.
SourceFDA label · active ingredient
Label datedMarch 2026
Pharmacist reviewAugust 2026
A fact about the active ingredient, from the FDA label. Content has been reviewed by a licensed pharmacist.