Drug interactions
Chlorzoxazone + Phenobarbital
Severity: Moderate
Chlorzoxazone and Phenobarbital: 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
Phenobarbital is a sedating anticonvulsant, and chlorzoxazone adds to drowsiness and psychomotor impairment. Phenobarbital also induces CYP enzymes, which could alter exposure to chlorzoxazone.
What this interaction means in plain words
Chlorzoxazone and Phenobarbital 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.
Why it happens
Additive central nervous system depression; phenobarbital enzyme induction may also speed chlorzoxazone clearance.
What to do
Monitor for excess sedation and use the lowest effective doses. Assess muscle relaxant response, as it may be reduced.
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 Chlorzoxazone
Frequently asked questions
Can I take Chlorzoxazone with Phenobarbital?
MediHelp rates the interaction as moderate. Chlorzoxazone and Phenobarbital 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. Phenobarbital is a sedating anticonvulsant, and chlorzoxazone adds to drowsiness and psychomotor impairment. Phenobarbital also induces CYP enzymes, which could alter exposure to chlorzoxazone.
How serious is the interaction between Chlorzoxazone and Phenobarbital?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excess sedation and use the lowest effective doses. Assess muscle relaxant response, as it may be reduced.
What other medicines interact with Chlorzoxazone?
MediHelp also lists interactions of Chlorzoxazone with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Chlorzoxazone page.
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