What the FDA labels say about taking them together
Atazanavir and efavirenz
Atazanavir's FDA label of August 6, 2025 names efavirenz in its drug interactions section, and efavirenz's label names atazanavir too. The efavirenz label: “Treatment-naive patients: When coadministered with efavirenz, the recommended dose of atazanavir is 400 mg with ritonavir 100 mg and efavirenz 600 mg. …”
Check it at the source: the atazanavir FDA label on DailyMed (effective August 6, 2025, Aurobindo Pharma Limited); the efavirenz FDA label on DailyMed (effective March 31, 2024, Cipla USA Inc.).
What does the atazanavir label say about efavirenz?
Atazanavir label, drug interactionsConcomitant Drug Class/Specific Drugs: Non-nucleoside Reverse Transcriptase Inhibitors (NNRTIs): efavirenz; Effect on Concentration of Atazanavir or Concomitant Drug: ↓ atazanavir; Clinical Comment: In HIV-treatment-naive adult patients: If atazanavir is combined with efavirenz, atazanavir 400 mg (two 200 mg capsules) should be administered with ritonavir 100 mg simultaneously once daily with food, and efavirenz 600 mg should be administered once daily on an empty stomach, preferably at bedtime. In HIV-treatment-experienced adult patients: Coadministration of atazanavir with efavirenz is not recommended.
Source: FDA drug label (Reyataz, NDA021567), E.R. Squibb & Sons, L.L.C., effective December 5, 2024 (SPL set 165cff62-b284-4a27-a65d-9ec8a5bfcdd8), via openFDA
Source: FDA drug label (Atazanavir Sulfate), Aurobindo Pharma Limited, effective August 6, 2025 (SPL set 7fbea274-d6b5-4faa-bbf0-05fefab42114), via openFDA; the full label on DailyMed
What does the efavirenz label say about atazanavir?
Efavirenz label, drug interactionsConcomitant Drug Class/Drug Name: Protease inhibitor: Atazanavir; Effect: ↓ atazanavir *; Clinical Comment: Treatment-naive patients: When coadministered with efavirenz, the recommended dose of atazanavir is 400 mg with ritonavir 100 mg (together once daily with food) and efavirenz 600 mg (once daily on an empty stomach, preferably at bedtime). Treatment-experienced patients: Coadministration of efavirenz and atazanavir is not recommended.
Source: FDA drug label (Efavirenz), Cipla USA Inc., effective March 31, 2024 (SPL set 92603fa5-7a2c-4bfb-9a70-aadb4fba952c), 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
| Atazanavir | Efavirenz | |
|---|---|---|
| Labeled for | HIV | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $2.23 per capsule 300 mg capsule | $1.28 per tablet 600 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