What the FDA labels say about taking them together
Erythromycin and estrogens conjugated
Estrogens conjugated's FDA label of June 4, 2026 names erythromycin in its drug interactions section; the erythromycin labels PlainMeds reads (4) do not name estrogens conjugated. The estrogens conjugated label: “Inhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice, may increase plasma concentrations of estrogens and may result in side effects.”
Check it at the source: the erythromycin FDA label on DailyMed (effective August 1, 2024, Teva Pharmaceuticals USA, Inc.); the estrogens conjugated FDA label on DailyMed (effective June 4, 2026, Wyeth Pharmaceuticals LLC, a subsidiary of Pfizer Inc.).
What does the erythromycin label say about estrogens conjugated?
Erythromycin's label (effective August 1, 2024) and its 3 other brand-application labels do 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 (Erythromycin), Teva Pharmaceuticals USA, Inc., effective August 1, 2024 (SPL set 75a0bd5a-d09f-483b-bfd8-f8343b149eb2), via openFDA; the full label on DailyMed
What does the estrogens conjugated label say about erythromycin?
Estrogens conjugated label, drug interactionsInhibitors of CYP3A4, such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir and grapefruit juice, may increase plasma concentrations of estrogens and may result in side effects.
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
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
| Erythromycin | Estrogens conjugated | |
|---|---|---|
| Labeled for | Bacterial infections, Acne | Menopause symptoms, Breast cancer, Osteoporosis |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.96 per tablet 250 mg tablet | $5.47 per tablet 0.625 mg tablet |
| Shortage now | No current entry | No current entry |
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