Chloramphenicol Injection and Acetaminophen: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Chloramphenicol Injection
Acetaminophen
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
Chloramphenicol toxicity (vomiting, hypotension, hypothermia)
Interaction Deep Dive
Concomitant use of acetaminophen (greater than or equal to 1 g four times daily) and chloramphenicol (greater than or equal to 500 mg every six hours) has been reported to increase, decrease, and have no change on the chloramphenicol half-life4.
Why it happens (mechanism)
Unknown
Literature reports
2 reports — tap to read
a) A study reported that the half-life of chloramphenicol increased from 2 to 3 hours to 18 to 24 hours in children who received concomitant acetaminophen therapy and from 3.25 hours to 15 hours in 6 adults similarly tested. Competitive metabolism was the proposed mechanism and a decrease in chloramphenicol dosage was advocated 1.
b) No pharmacokinetic interaction occurred between intravenous chloramphenicol succinate and oral acetaminophen in acutely febrile children during concomitant therapy. It is suggested that acetaminophen and chloramphenicol (succinate) can be given concomitantly in children in currently recommended doses without alterations in chloramphenicol disposition. However, concomitant administration of intravenous chloramphenicol and oral acetaminophen was reported to result in significant increases in the clearance of chloramphenicol with decreases in the peak chloramphenicol serum concentrations and elimination half-life. It is suggested that these effects are related to increased glucuronidation of chloramphenicol. Until further data is available, serum level monitoring is indicated during combined therapy 23.
Common questions
Can I take Chloramphenicol Injection and Acetaminophen together?
Chloramphenicol toxicity (vomiting, hypotension, hypothermia) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Chloramphenicol Injection and Acetaminophen interaction?
It is rated minor. Usually limited clinical impact.
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 Chloramphenicol Injection or Acetaminophen 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 (4)
- Buchanan N & Moodley BP: Interaction between chloramphenicol and paracetamol. Br Med J 1979; 2:307-308. PubMed
- Spika JS, Davis DJ, Martin SR, et al: Interaction between chloramphenicol and acetaminophen. Arch Dis Child 1986; 61:1121-1124. DOI
- Kearns GL, Bocchini JA Jr, Brown RD, et al: Absence of a pharmacokinetic interaction between chloramphenicol and acetaminophen in children. J Pediatr 1985; 107:134-139. PubMed
- Stein CM, Thornhill DP, Neill P, et al: Lack of effect of paracetamol on the pharmacokinetics of chloramphenicol. Br J Clin Pharmacol 1989; 2:262-264. DOI
Keep reading about Chloramphenicol Injection
Keep reading about Acetaminophen
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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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