Drug interactions
Ampicillin + Chloramphenicol
Severity: Moderate
Ampicillin and Chloramphenicol: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Chloramphenicol may antagonize the bactericidal effect of ampicillin, and worse outcomes have been suggested in some serious infections such as meningitis. The data are mostly in vitro or observational.
What this interaction means in plain words
Ampicillin and Chloramphenicol can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Ampicillin belongs to Anti Bacterial; Chloramphenicol belongs to Anti Bacterial.
Why it happens
Pharmacodynamic antagonism: inhibition of bacterial protein synthesis and growth reduces penicillin killing.
What to do
Avoid the combination in meningitis, endocarditis and other infections requiring bactericidal therapy; choose one active agent based on susceptibility.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Ampicillin
- Allopurinol + Ampicillin Moderate
- Ampicillin + Bcg vaccine live Moderate
- Ampicillin + Chloroquine Moderate
- Ampicillin + Cholera vaccine Moderate
- Ampicillin + Demeclocycline Moderate
- Ampicillin + Eravacycline Moderate
Other interactions of Chloramphenicol
Frequently asked questions
Can I take Ampicillin with Chloramphenicol?
MediHelp rates the interaction as moderate. Ampicillin and Chloramphenicol can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Chloramphenicol may antagonize the bactericidal effect of ampicillin, and worse outcomes have been suggested in some serious infections such as meningitis. The data are mostly in vitro or observational.
How serious is the interaction between Ampicillin and Chloramphenicol?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination in meningitis, endocarditis and other infections requiring bactericidal therapy; choose one active agent based on susceptibility.
What other medicines interact with Ampicillin?
MediHelp also lists interactions of Ampicillin with, for example, Allopurinol, Bcg vaccine live, Chloroquine. The full list is on the Ampicillin page.
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