Dolutegravir/Lamivudine and Phenobarbital Interaction
Drug interaction information between Dolutegravir/Lamivudine and Phenobarbital.
Dolutegravir/Lamivudine and Phenobarbital have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Dolutegravir/Lamivudine and Phenobarbital. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Phenobarbital speeds up the breakdown of dolutegravir in your system, which can prevent the medication from working properly.
What To Do
This combination should be avoided because there is not enough research to provide a safe dosing plan.
FDA Label Information
Anticonvulsants: Oxcarbazepine Phenytoin Phenobarbital ↓Dolutegravir Avoid coadministration with DOVATO because there are insufficient data to make dosing recommendations.
Dolutegravir/Lamivudine Also Interacts With
- Dofetilide major
- Metformin moderate
- Oxcarbazepine moderate
- Phenytoin moderate
- Carbamazepine minor
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Ranolazine major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
Frequently Asked Questions
Can I take Dolutegravir/Lamivudine and Phenobarbital together?
This is a moderate interaction. This combination should be avoided because there is not enough research to provide a safe dosing plan.
How serious is the interaction between Dolutegravir/Lamivudine and Phenobarbital?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Dolutegravir/Lamivudine and Phenobarbital interact?
Phenobarbital speeds up the breakdown of dolutegravir in your system, which can prevent the medication from working properly.
Understanding the Dolutegravir/Lamivudine and Phenobarbital Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Dolutegravir/Lamivudine belongs to the Integrase Inhibitor / NRTI Combination class and Phenobarbital belongs to the Anticonvulsant (Barbiturate) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Phenobarbital speeds up the breakdown of dolutegravir in your system, which can prevent the medication from working properly. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Dolutegravir/Lamivudine has 9 total documented interactions on file in this dataset, and Phenobarbital has 59. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: This combination should be avoided because there is not enough research to provide a safe dosing plan. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Dolutegravir/Lamivudine or Phenobarbital based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.