What the FDA labels say about taking them together
Erlotinib and ritonavir
Erlotinib's FDA label of June 10, 2024 names ritonavir in its drug interactions section; the ritonavir label PlainMeds reads does not name erlotinib. The erlotinib label: “Avoid co-administering erlotinib with strong CYP3A4 inhibitors or a combined CYP3A4 and CYP1A2 inhibitor (e.g., ciprofloxacin).”
Check it at the source: the erlotinib FDA label on DailyMed (effective June 10, 2024, Alembic Pharmaceuticals Limited); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the erlotinib label say about ritonavir?
Erlotinib label, drug interactionsAvoid co-administering erlotinib with strong CYP3A4 inhibitors (e.g., boceprevir, clarithromycin, conivaptan, indinavir, itraconazole, ketoconazole, lopinavir/ritonavir, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telithromycin, voriconazole, grapefruit or grapefruit juice) or a combined CYP3A4 and CYP1A2 inhibitor (e.g., ciprofloxacin).
Source: FDA drug label (ERLOTINIB HYDROCHLORIDE), Alembic Pharmaceuticals Limited, effective June 10, 2024 (SPL set ab6f3cb3-34a8-4492-a5d7-fb6b055a2d6b), via openFDA; the full label on DailyMed
What does the ritonavir label say about erlotinib?
Ritonavir's label (effective July 23, 2026) does not name erlotinib in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), 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
| Erlotinib | Ritonavir | |
|---|---|---|
| Labeled for | Lung cancer | HIV |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.607 per tablet 100 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
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