Cimetidine and Levofloxacin Interaction
Drug interaction information between Cimetidine and Levofloxacin.
Cimetidine and Levofloxacin have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Cimetidine and Levofloxacin. 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
Cimetidine makes it harder for the kidneys to clear levofloxacin, causing the antibiotic to stay in the body slightly longer.
What To Do
No dosage changes are needed, so you can safely take these medications together as prescribed.
FDA Label Information
7.8 Probenecid and Cimetidine No significant effect of probenecid or cimetidine on the Cmax of levofloxacin was observed in a clinical study involving healthy volunteers. The AUC and t 1/2 of levofloxacin were higher while CL/F and CLR were lower during concomitant treatment of levofloxacin with probenecid or cimetidine compared to levofloxacin alone. However, these changes do not warrant dosage adjustment for levofloxacin when probenecid or cimetidine is co-administered.
Cimetidine Also Interacts With
- Posaconazole major
- Risperidone major
- Valproate major
- Empagliflozin moderate
- Empagliflozin/Linagliptin moderate
Levofloxacin Also Interacts With
- Probenecid major
- Theophylline moderate
- Warfarin minor
- Cyclosporine minor
- Digoxin minor
Frequently Asked Questions
Can I take Cimetidine and Levofloxacin together?
This is a major interaction. No dosage changes are needed, so you can safely take these medications together as prescribed.
How serious is the interaction between Cimetidine and Levofloxacin?
This interaction is classified as "major" severity by the FDA. Major interactions may be life-threatening or cause serious side effects.
Why do Cimetidine and Levofloxacin interact?
Cimetidine makes it harder for the kidneys to clear levofloxacin, causing the antibiotic to stay in the body slightly longer.
Understanding the Cimetidine and Levofloxacin Interaction
FDA-approved prescribing information for these two drugs flags their combination as a major-severity interaction. Cimetidine belongs to the H2 Receptor Antagonist class and Levofloxacin belongs to the Fluoroquinolone Antibiotic class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Cimetidine makes it harder for the kidneys to clear levofloxacin, causing the antibiotic to stay in the body slightly longer. 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. Cimetidine has 77 total documented interactions on file in this dataset, and Levofloxacin has 8. 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: No dosage changes are needed, so you can safely take these medications together as prescribed. 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 Cimetidine or Levofloxacin 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.