What the FDA labels say about taking them together
Estrogens conjugated and rifampin
Estrogens conjugated's FDA label of June 4, 2026 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name estrogens conjugated. The estrogens conjugated label: “Inducers of CYP3A4, such as St. John's Wort ( Hypericum perforatum ) preparations, phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of estrogens, possibly resulting in a decrease in …”
Check it at the source: the estrogens conjugated FDA label on DailyMed (effective June 4, 2026, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the estrogens conjugated label say about rifampin?
Estrogens conjugated label, drug interactionsInducers of CYP3A4, such as St. John's Wort ( Hypericum perforatum ) preparations, phenobarbital, carbamazepine, and rifampin, may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile.
Source: FDA drug label (Premarin), Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc., effective June 4, 2026 (SPL set 258e1602-a3cf-4ccc-ca80-73dbbfb812ff), via openFDA; the full label on DailyMed
What does the rifampin label say about estrogens conjugated?
Rifampin's label (effective February 11, 2026) does not name estrogens conjugated in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Estrogens conjugated | Rifampin | |
|---|---|---|
| Labeled for | Menopause symptoms, Breast cancer, Osteoporosis | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $5.47 per tablet 0.625 mg tablet | $0.679 per capsule 300 mg capsule |
| Shortage now | No current entry | In shortage |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once