Cephalexin and Probenecid Interaction

Drug interaction information between Cephalexin and Probenecid.

Cephalexin and Probenecid have a documented moderate interaction in FDA labeling.

FDA drug labeling documents a moderate-severity interaction between Cephalexin and Probenecid. 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.

Drug A

Cephalexin

First-Generation Cephalosporin

Drug B

Probenecid

Uricosuric Agent

How They Interact

Probenecid blocks your kidneys from removing cephalexin from your body. This causes the antibiotic to build up to higher levels than intended.

What To Do

You should not take these two medications together unless specifically directed by your doctor.

FDA Label Information

( 7.1 ) Probenecid-The renal excretion of cephalexin is inhibited by probenecid. Co-administration of probenecid with cephalexin is not recommended. 7.2 Probenecid The renal excretion of cephalexin is inhibited by probenecid.

Cephalexin Also Interacts With

View all Cephalexin interactions →

Frequently Asked Questions

Can I take Cephalexin and Probenecid together?

This is a moderate interaction. You should not take these two medications together unless specifically directed by your doctor.

How serious is the interaction between Cephalexin and Probenecid?

This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.

Why do Cephalexin and Probenecid interact?

Probenecid blocks your kidneys from removing cephalexin from your body. This causes the antibiotic to build up to higher levels than intended.

Understanding the Cephalexin and Probenecid Interaction

FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Cephalexin belongs to the First-Generation Cephalosporin class and Probenecid belongs to the Uricosuric Agent class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Probenecid blocks your kidneys from removing cephalexin from your body. 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. Cephalexin has 2 total documented interactions on file in this dataset, and Probenecid has 37. 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: You should not take these two medications together unless specifically directed by your doctor. 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 Cephalexin or Probenecid 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.