Drug interactions
Phenobarbital + Tetracycline
Severity: Minor
Phenobarbital and Tetracycline: minor 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
Phenobarbital is an enzyme inducer and may shorten the half-life of some tetracyclines. This is well described for doxycycline, but tetracycline itself is mostly eliminated unchanged by the kidney so the effect is small.
What this interaction means in plain words
Phenobarbital and Tetracycline have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Hepatic enzyme induction by phenobarbital may modestly increase tetracycline clearance.
What to do
No routine action needed for tetracycline. Watch for treatment failure and consider an alternative antibiotic if the response is poor.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Tetracycline
- Acitretin + Tetracycline Contraindicated
- Methoxyflurane + Tetracycline Contraindicated
- Isotretinoin + Tetracycline Major
- Palovarotene + Tetracycline Major
- Strontium ranelate + Tetracycline Major
- Tetracycline + Tretinoin Major
Frequently asked questions
Can I take Phenobarbital with Tetracycline?
MediHelp rates the interaction as minor. Phenobarbital and Tetracycline have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenobarbital is an enzyme inducer and may shorten the half-life of some tetracyclines. This is well described for doxycycline, but tetracycline itself is mostly eliminated unchanged by the kidney so the effect is small.
How serious is the interaction between Phenobarbital and Tetracycline?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action needed for tetracycline. Watch for treatment failure and consider an alternative antibiotic if the response is poor.
What other medicines interact with Tetracycline?
MediHelp also lists interactions of Tetracycline with, for example, Acitretin, Methoxyflurane, Isotretinoin. The full list is on the Tetracycline page.
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