Tamoxifen and Bupropion Interaction
Drug interaction information between Tamoxifen and Bupropion.
Tamoxifen and Bupropion have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Tamoxifen and Bupropion. 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
Bupropion prevents tamoxifen from being changed into its active form, which could make the tamoxifen less effective at treating cancer.
What To Do
Your doctor may suggest a different medication that does not interfere with how tamoxifen works.
FDA Label Information
Drugs that require metabolic activation by CYP2D6 to be effective (e.g., tamoxifen), theoretically could have reduced efficacy when administered concomitantly with inhibitors of CYP2D6 such as bupropion.
Tamoxifen Also Interacts With
- Warfarin major
- Anastrozole major
- Letrozole moderate
- Desvenlafaxine minor
- Letrozole (Fertility) minor
Bupropion Also Interacts With
- Tranylcypromine major
- Theophylline moderate
- Isavuconazonium moderate
- Metoprolol minor
- Sertraline minor
Frequently Asked Questions
Can I take Tamoxifen and Bupropion together?
This is a minor interaction. Your doctor may suggest a different medication that does not interfere with how tamoxifen works.
How serious is the interaction between Tamoxifen and Bupropion?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Tamoxifen and Bupropion interact?
Bupropion prevents tamoxifen from being changed into its active form, which could make the tamoxifen less effective at treating cancer.
Understanding the Tamoxifen and Bupropion Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Tamoxifen belongs to the Selective Estrogen Receptor Modulator (SERM) class and Bupropion belongs to the Norepinephrine-Dopamine Reuptake Inhibitor (NDRI) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Bupropion prevents tamoxifen from being changed into its active form, which could make the tamoxifen less effective at treating cancer. 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. Tamoxifen has 10 total documented interactions on file in this dataset, and Bupropion has 35. 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: Your doctor may suggest a different medication that does not interfere with how tamoxifen works. 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 Tamoxifen or Bupropion 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.