Efavirenz and Azithromycin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Efavirenz
No brand names on recordAzithromycin
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
An increased risk of QT interval prolongation
Interaction Deep Dive
Consider alternatives to efavirenz when used concomitantly with another drug that prolongs the QT interval or has a known risk of torsade de pointes, because additive effects on the QT interval may occur. In a QT study of 58 healthy subjects, the mean Cmax in patients with the CYP2B6 *6/*6 genotype was 2.25-fold higher than the mean Cmax in those with the CYP2B6 *1/*1 genotype and the mean QTc interval prolongation was 8.7 milliseconds in subjects with the CYP2B6 *6/*6 genotype1.
Why it happens (mechanism)
Additive QT interval prolongation
Literature reports
1 report — tap to read
a) In a QT study of healthy subjects (N=58) enriched for CYP2B6 polymorphisms, a positive association between efavirenz concentration and QTc prolongation was observed. Following administration of efavirenz 600 mg/day for 14 days, the mean Cmax in subjects with the CYP2B6 *6/*6 genotype was 2.25-fold higher than the mean Cmax in subjects with the CYP2B6 *1/*1 genotype and the mean QTc interval prolongation was 8.7 milliseconds in subjects with the CYP2B6 *6/*6 genotype 1.
Common questions
Can I take Efavirenz and Azithromycin together?
An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Efavirenz and Azithromycin 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Efavirenz or Azithromycin 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 (1)
- 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 Efavirenz
Keep reading about Azithromycin
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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