What the FDA labels say about taking them together
Erythromycin and nirmatrelvir/ritonavir
Nirmatrelvir/ritonavir's FDA label of February 19, 2026 names erythromycin in its drug interactions section; the erythromycin labels PlainMeds reads (4) do not name nirmatrelvir/ritonavir. The nirmatrelvir/ritonavir label: “Refer to the respective prescribing information for anti-infective dose adjustment.”
Check it at the source: the erythromycin FDA label on DailyMed (effective August 1, 2024, Teva Pharmaceuticals USA, Inc.); the nirmatrelvir/ritonavir FDA label on DailyMed (effective February 19, 2026, Pfizer Laboratories Div Pfizer Inc).
What does the erythromycin label say about nirmatrelvir/ritonavir?
Erythromycin's label (effective August 1, 2024) and its 3 other brand-application labels do not name nirmatrelvir/ritonavir 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 nirmatrelvir/ritonavir label say about erythromycin?
Nirmatrelvir/ritonavir label, drug interactionsDrug Class: Anti-infective; Drugs within Class: clarithromycin, erythromycin; Effect on Concentration: ↑ clarithromycin ↑ erythromycin; Clinical Comments: Refer to the respective prescribing information for anti-infective dose adjustment.
Source: FDA drug label (Paxlovid), Pfizer Laboratories Div Pfizer Inc, effective February 19, 2026 (SPL set 8a99d6d6-fd9e-45bb-b1bf-48c7f761232a), 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 | Nirmatrelvir/ritonavir | |
|---|---|---|
| Labeled for | Bacterial infections, Acne | COVID-19 |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $1.96 per tablet 250 mg tablet | $49.24 per unit 300-100 mg dose pack |
| 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