Probenecid and Cefotaxime Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Probenecid
No brand names on recordCefotaxime Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased cefotaxime plasma concentrations
Interaction Deep Dive
Probenecid interferes with the renal tubular transfer of cefotaxime causing a reduction in the total clearance by approximately 50% and an increase in the steady-state plasma concentration by approximately 80%. The administration of more than 6 g/day of cefotaxime in a patient using concomitant probenecid should be avoided1.
Why it happens (mechanism)
Decreased renal clearance of cefotaxime by probenecid
Literature reports
2 reports — tap to read
a) The steady-state plasma concentration of cefotaxime increased by approximately 80% after 4 doses of probenecid 500 mg were administered to 3 healthy subjects who were receiving continuous infusions of cefotaxime. Initially, the subjects were given a single IV and oral dose of 500 mg each. The subjects then received 2 additional oral doses of probenecid 500 mg given at approximate hourly intervals 1.
b) The total clearance of cefotaxime decreased by approximately 50% after 6 healthy subjects received oral probenecid 500 mg every 6 hours with cefotaxime 1 gram infused over 5 minutes 1.
Common questions
Can I take Probenecid and Cefotaxime Injection together?
Increased cefotaxime plasma concentrations Always confirm with your pharmacist or prescriber before making any change.
How serious is the Probenecid and Cefotaxime Injection interaction?
It is rated moderate. Can be significant — usually manageable with monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Probenecid or Cefotaxime Injection need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there anything you'd monitor while I'm on both?
References (1)
- Product Information: CLAFORAN(R) injection, cefotaxime injection. sanofi-aventis U.S. LLC (per FDA), Bridgewater, NJ, 2011. DailyMed
Keep reading about Probenecid
Keep reading about Cefotaxime Injection
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
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