Nevirapine and Efavirenz: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Nevirapine
Efavirenz
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced efavirenz exposure, reduced nevirapine exposure and an increased adverse events
Interaction Deep Dive
Concomitant use of efavirenz and nevirapine is not recommended. In studies in HIV-infected patients, coadministration of efavirenz and nevirapine led to decreased efavirenz concentration. Additionally, in clinical trials, the combination of efavirenz and nevirapine was associated with increased adverse events and there was no additional improvement seen in clinical efficacy. Safe and effective dose adjustments for this combination have not been determined12. Do not administer efavirenz with other NNRTIs such as nevirapine as coadministration may decrease the plasma concentrations of both efavirenz and nevirapine 3.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of efavirenz; induction of CYP3A4-mediated metabolism of nevirapine; induction of CYP2B6-mediated metabolism of nevirapine
Literature reports
1 report — tap to read
a) In a study of patients with HIV infection (n=17), coadministration of efavirenz 600 mg once daily with nevirapine 200 mg once daily for 14 days, followed by nevirapine 400 mg once daily for 14 days, decreased efavirenz AUC by 28% (90% CI 14% to 34%), Cmax by 12% (90% CI 1% to 21%), and Cmin by 32% (90% CI 19% to 35%) 12.
Common questions
Can I take Nevirapine and Efavirenz together?
Reduced efavirenz exposure, reduced nevirapine exposure and an increased adverse events Always confirm with your pharmacist or prescriber before making any change.
How serious is the Nevirapine and Efavirenz interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Nevirapine or Efavirenz need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Product Information: VIRAMUNE(R) oral suspension, nevirapine oral suspension. Boehringer Ingelheim Pharmaceuticals Inc (per FDA), Ridgefield, CT, 2024. DailyMed
- Product Information: VIRAMUNE XR(R) oral extended-release tablets, nevirapine oral extended-release tablets. Boehringer Ingelheim Pharmaceuticals Inc (per FDA), Ridgefield, CT, 2024. DailyMed
- Product Information: SUSTIVA(R) oral capsules, oral tablets, efavirenz oral capsules, oral tablets. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2023. DailyMed
Keep reading about Nevirapine
Keep reading about Efavirenz
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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