Chloramphenicol Injection and Ceftazidime: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chloramphenicol Injection
Ceftazidime
No brand names on record
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
Decreased ceftazidime effectiveness
Interaction Deep Dive
Chloramphenicol has been shown to be antagonistic to beta-lactam antibiotics2. A case report demonstrated that the combination of ceftazidime and chloramphenicol was less effective than ceftazidime alone for treating a young infant with Salmonella meningitis 1.
Why it happens (mechanism)
Antagonism
Literature reports
1 report — tap to read
a) Concomitant administration of ceftazidime (bactericidal agent) and chloramphenicol (bacteriostatic agent) was reported to result in both in vitro and in vivo antagonism during therapy of a 2.5-month-old boy with Salmonella meningitis. Only minimal response, with persistent fever, was observed with the combination of chloramphenicol 75 to 100 mg/kg daily plus ceftazidime 100 mg/kg daily over a period of four days. Withdrawal of chloramphenicol and single-agent therapy with ceftazidime 150 mg/kg daily in four divided doses resulted in uneventful recovery 1.
Common questions
Can I take Chloramphenicol Injection and Ceftazidime together?
Decreased ceftazidime effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chloramphenicol Injection and Ceftazidime 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.
Questions for your pharmacist
- Does my dose of Chloramphenicol Injection or Ceftazidime 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 (2)
Keep reading about Chloramphenicol Injection
Keep reading about Ceftazidime
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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