What the FDA labels say about taking them together
Erythromycin and vardenafil
Vardenafil's FDA label of January 5, 2026 names erythromycin in its drug interactions section; the erythromycin labels PlainMeds reads (4) do not name vardenafil. The vardenafil label: “Interactions with Strong or Moderate CYP3A4 Inhibitors Concomitant administration with strong CYP3A4 inhibitors or moderate CYP3A4 inhibitors (such as erythromycin) increases plasma concentrations of vardenafil.”
Check it at the source: the erythromycin FDA label on DailyMed (effective August 1, 2024, Teva Pharmaceuticals USA, Inc.); the vardenafil FDA label on DailyMed (effective January 5, 2026, Zydus Pharmaceuticals USA Inc.).
What does the erythromycin label say about vardenafil?
Erythromycin's label (effective August 1, 2024) and its 3 other brand-application labels do not name vardenafil 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 vardenafil label say about erythromycin?
Vardenafil label, drug interactionsConsequently, it is recommended not to exceed a single 2.5 mg vardenafil dose in a 72-hour period when used in combination with ritonavir. [See Dosage and Administration ( 2.4 ) and Warnings and Precautions ( 5.2 ).] Cobicistat with vardenafil can result in increased plasma concentrations, therefore it is recommended that a single 2.5 mg dose of vardenafil should not be exceeded in a 72 hours period. [See Dosage and Administration ( 2.4 ) and Warnings and Precautions ( 5 ).] Moderate CYP3A4 inhibitors Erythromycin (500 mg t.i.d.) produced a 4-fold increase in vardenafil AUC and a 3-fold increase in C max when coadministered with vardenafil 5 mg in healthy volunteers.
Vardenafil label, warnings and precautionsInteractions with Strong or Moderate CYP3A4 Inhibitors Concomitant administration with strong CYP3A4 inhibitors (such as ritonavir, indinavir, cobicistat, ketoconazole) or moderate CYP3A4 inhibitors (such as erythromycin) increases plasma concentrations of vardenafil.
Source: FDA drug label (VARDENAFIL), Zydus Pharmaceuticals USA Inc., effective January 5, 2026 (SPL set 5876e062-e604-42a7-99c3-5da30b8dac06), 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 | Vardenafil | |
|---|---|---|
| Labeled for | Bacterial infections, Acne | Erectile dysfunction |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $1.96 per tablet 250 mg tablet | $2.79 per tablet 20 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