Drug interactions
penicillin + tetracycline
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.
Overview
Tetracyclines may diminish the bactericidal activity of penicillins, potentially reducing clinical efficacy in serious infections.
Mechanism of action
Pharmacodynamic antagonism: tetracycline is bacteriostatic (inhibits protein synthesis and slows growth), which can reduce penicillin’s bactericidal cell-wall activity that requires active bacterial proliferation.
Clinical management
Avoid concurrent use for serious infections where penicillin efficacy is critical (e.g., meningitis, bacteremia). If combination is unavoidable, consider alternative non-tetracycline or sequence therapy and monitor clinical response closely.
Drug reference
References
- Tetracycline Prescribing Information (US Label) – Drug Interactions: may interfere with bactericidal action of penicillin — FDA Label
- Tetracyclines and Penicillins – Drug Interaction Monograph — Lexicomp
- Penicillin and tetracycline Interactions — Drugs.com
Frequently asked questions
Can I take penicillin with tetracycline?
The interaction is rated: Moderate. Tetracyclines may diminish the bactericidal activity of penicillins, potentially reducing clinical efficacy in serious infections.
How serious is the interaction between penicillin and tetracycline?
The interaction is rated: Moderate. Evidence level: High.
How is the interaction between penicillin and tetracycline managed?
Avoid concurrent use for serious infections where penicillin efficacy is critical (e.g., meningitis, bacteremia). If combination is unavoidable, consider alternative non-tetracycline or sequence therapy and monitor clinical response closely.
Why do penicillin and tetracycline interact?
Pharmacodynamic antagonism: tetracycline is bacteriostatic (inhibits protein synthesis and slows growth), which can reduce penicillin’s bactericidal cell-wall activity that requires active bacterial proliferation.
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