Acyclovir and Cidofovir Interaction
Drug interaction information between Acyclovir and Cidofovir.
Acyclovir and Cidofovir have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Acyclovir and Cidofovir. 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
Probenecid is given with cidofovir and can slow down the removal of acyclovir through the kidneys. This can lead to an increase in the amount of acyclovir in your blood.
What To Do
Your doctor may need to adjust your acyclovir dosage. Watch for any increased side effects while taking both medications.
FDA Label Information
Drug Interactions Probenecid Probenecid is known to interact with the metabolism or renal tubular excretion of many drugs (e.g., acetaminophen, acyclovir, angiotensin-converting enzyme inhibitors, aminosalicylic acid, barbiturates, benzodiazepines, bumetanide, clofibrate, methotrexate, famotidine, furosemide, nonsteroidal anti-inflammatory agents, theophylline, and zidovudine).
Acyclovir Also Interacts With
- Bictegravir/Emtricitabine/Tenofovir minor
- Emtricitabine/Tenofovir minor
- Meperidine minor
- Tenofovir Disoproxil minor
- Tizanidine minor
Cidofovir Also Interacts With
- Vancomycin major
- Gentamicin major
- Tobramycin major
- Amikacin major
- Amphotericin B major
Frequently Asked Questions
Can I take Acyclovir and Cidofovir together?
This is a minor interaction. Your doctor may need to adjust your acyclovir dosage. Watch for any increased side effects while taking both medications.
How serious is the interaction between Acyclovir and Cidofovir?
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 Acyclovir and Cidofovir interact?
Probenecid is given with cidofovir and can slow down the removal of acyclovir through the kidneys. This can lead to an increase in the amount of acyclovir in your blood.
Understanding the Acyclovir and Cidofovir Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Acyclovir belongs to the Antiviral (Nucleoside Analog) class and Cidofovir belongs to the Antiviral (Nucleotide Analog) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Probenecid is given with cidofovir and can slow down the removal of acyclovir through the kidneys. 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. Acyclovir has 7 total documented interactions on file in this dataset, and Cidofovir has 16. 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 need to adjust your acyclovir dosage. 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 Acyclovir or Cidofovir 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.