Chloramphenicol Injection and Cyclophosphamide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chloramphenicol Injection
Cyclophosphamide
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 cyclophosphamide effectiveness
Interaction Deep Dive
Cyclophosphamide is a prodrug which is converted to active alkylating metabolites. Chloramphenicol presumably slows the metabolism of cyclophosphamide (half-life; 7.5 compared to 11.5 hours) and decreases the rate of production of cyclophosphamide active metabolites12.
Why it happens (mechanism)
Decreased hepatic metabolism
Common questions
Can I take Chloramphenicol Injection and Cyclophosphamide together?
Decreased cyclophosphamide effectiveness Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chloramphenicol Injection and Cyclophosphamide 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 "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Chloramphenicol Injection or Cyclophosphamide 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)
- Faber OK, Mouridsen HT, & Skovsted L: The effect of chloramphenicol and sulphaphenazole on the biotransformation of cyclophosphamide in man. Br J Clin Pharmacol 1975; 2:281-285. PubMed
- Mouridsen HT, Witten J, Frederiksen PL, et al: Studies on the correlation between rate of biotransformation and haematological toxicity of cyclophosphamide (letter). Acta Pharmacol Toxicol 1978; 43:328-330. DOI
Keep reading about Chloramphenicol Injection
Keep reading about Cyclophosphamide
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