Atazanavir and Amitriptyline: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 2, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Amitriptyline
Atazanavir
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.
Here's what's going on. Amitriptyline (Elavil) and atazanavir (Reyataz) can each affect your heart's rhythm by slightly stretching out a part of the heartbeat called the QT interval. Taken together, that effect can add up. On top of that, atazanavir may cause more amitriptyline to build up in your body, which can make its side effects (like drowsiness, dry mouth, or a fast or irregular heartbeat) stronger.
The good news: this is a theoretical concern, not something proven in studies, and your care team can manage it. They may start amitriptyline at a low dose and adjust slowly. Please don't change anything on your own. Just check in with your pharmacist or doctor.
Effect: Additive QT prolongation, plus potentially increased TCA exposure, raising the risk of serious arrhythmia (including torsades).
- Mechanism: Additive QTc prolongation; amitriptyline is a CYP-metabolized substrate and atazanavir is a CYP3A4 inhibitor, which can increase TCA plasma levels. Neither is a prodrug here.
- Direction: Increased amitriptyline effect and additive cardiac risk.
- Evidence: Theoretical; combination not formally studied.
- Onset: Unspecified.
- Management: Use lowest feasible initial/maintenance TCA dose with careful titration to response. Monitor ECG/QTc, correct electrolytes (K+, Mg2+), and review other QT-prolonging agents.
What happens
Increased TCA exposure and an increased risk of QT interval prolongation
Interaction Deep Dive
The combined use of atazanavir with tricyclic antidepressants has not been the subject of formal study. Nevertheless, giving atazanavir together with tricyclic antidepressants that prolong the QT interval carries the potential for serious and/or life-threatening adverse events, such as prolongation of the QT interval 1. When atazanavir and tricyclic antidepressants (TCA) are administered together, it is advised to titrate the antidepressant dose carefully toward the intended effect, employing the lowest possible starting or maintenance dose, along with monitoring of the antidepressant response 2.
Why it happens (mechanism)
Additive QT interval prolongation
How to manage this interaction
This is manageable with your care team. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise.
- Your team may start amitriptyline at the lowest feasible dose and titrate slowly to the effect you need.
- They may monitor you more closely, which can include checking your heart rhythm (ECG) and watching how well the antidepressant is working.
- Tell your pharmacist or doctor about any fainting, palpitations, or a fast or irregular heartbeat.
- Mention any other medicines you take, since some can also affect QT.
Management is individual — confirm any change with your pharmacist or prescriber.
Common questions
Can I take Atazanavir and Amitriptyline together?
Amitriptyline and atazanavir can both prolong the QT interval and the combination may raise amitriptyline levels, so your care team will likely use the lowest effective TCA dose and monitor your heart. Keep taking both as prescribed and report any palpitations or fainting. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Atazanavir and Amitriptyline 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 is the Atazanavir and Amitriptyline interaction managed?
This is manageable with your care team. Keep taking both medicines exactly as prescribed unless your prescriber tells you otherwise. Your team may start amitriptyline at the lowest feasible dose and titrate slowly to the effect you need. They may monitor you more closely, which can include checking your heart rhythm (ECG) and watching how well the antidepressant is working. Tell your pharmacist or… Management is individual — always follow your own care team's guidance.
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 Atazanavir or Amitriptyline 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 (2)
- Product Information: REYATAZ(R) oral capsules, oral powder, atazanavir oral capsules, oral powder. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2020. DailyMed
- Product Information: EVOTAZ(R) oral tablets, atazanavir cobicistat oral tablets. Bristol-Myers Squibb Company (per FDA), Princeton, NJ, 2023. DailyMed
Keep reading about Amitriptyline
Keep reading about Atazanavir
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist