Ganciclovir and Trimethoprim Interaction
Drug interaction information between Ganciclovir and Trimethoprim.
Ganciclovir and Trimethoprim have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Ganciclovir and Trimethoprim. 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
Both medications can be hard on the kidneys and may lower your blood cell counts. Using them at the same time increases the chance of these serious side effects.
What To Do
Use this combination only if your doctor decides the benefits are worth the risks. Your doctor will need to check your blood and kidney health often.
FDA Label Information
Other drugs associated with myelosuppression or nephrotoxicity (e.g., dapsone, doxorubicin, flucytosine, hydroxyurea, pentamidine, tacrolimus, trimethoprim/ sulfamethoxazole, vinblastine, vincristine and zidovudine) Unknown Because of potential for higher toxicity, coadministration with Ganciclovir Injection should be considered only if the potential benefits are judged to outweigh the risks.
Ganciclovir Also Interacts With
- Cyclosporine moderate
- Amphotericin B moderate
- Probenecid minor
- Bictegravir/Emtricitabine/Tenofovir minor
- Emtricitabine/Tenofovir minor
Trimethoprim Also Interacts With
- Theophylline major
- Prenatal Multivitamin moderate
- Spironolactone moderate
- Spironolactone (Acne) moderate
- Metformin minor
Frequently Asked Questions
Can I take Ganciclovir and Trimethoprim together?
This is a minor interaction. Use this combination only if your doctor decides the benefits are worth the risks. Your doctor will need to check your blood and kidney health often.
How serious is the interaction between Ganciclovir and Trimethoprim?
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 Ganciclovir and Trimethoprim interact?
Both medications can be hard on the kidneys and may lower your blood cell counts. Using them at the same time increases the chance of these serious side effects.
Understanding the Ganciclovir and Trimethoprim Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Ganciclovir belongs to the Antiviral (Nucleoside Analog) class and Trimethoprim belongs to the Dihydrofolate Reductase Inhibitor class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Both medications can be hard on the kidneys and may lower your blood cell counts. 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. Ganciclovir has 9 total documented interactions on file in this dataset, and Trimethoprim has 22. 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: Use this combination only if your doctor decides the benefits are worth the risks. 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 Ganciclovir or Trimethoprim 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.