Drug interactions
Chlordiazepoxide + Phenytoin
Severity: Moderate
Chlordiazepoxide and Phenytoin: 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
Phenytoin is an enzyme inducer and may lower chlordiazepoxide exposure, reducing its anxiolytic or anticonvulsant effect. Chlordiazepoxide has also been reported to alter phenytoin levels unpredictably, in either direction.
What this interaction means in plain words
Chlordiazepoxide and Phenytoin 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.
Chlordiazepoxide belongs to Central Nervous System; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and other hepatic enzymes, increasing benzodiazepine metabolism; the effect of benzodiazepines on phenytoin levels is variable and poorly defined.
What to do
Monitor clinical response to chlordiazepoxide and increase the dose if needed. Check phenytoin serum concentrations when starting or stopping the benzodiazepine.
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 Chlordiazepoxide
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Chlordiazepoxide with Phenytoin?
MediHelp rates the interaction as moderate. Chlordiazepoxide and Phenytoin 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. Phenytoin is an enzyme inducer and may lower chlordiazepoxide exposure, reducing its anxiolytic or anticonvulsant effect. Chlordiazepoxide has also been reported to alter phenytoin levels unpredictably, in either direction.
How serious is the interaction between Chlordiazepoxide and Phenytoin?
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 clinical response to chlordiazepoxide and increase the dose if needed. Check phenytoin serum concentrations when starting or stopping the benzodiazepine.
What other medicines interact with Chlordiazepoxide?
MediHelp also lists interactions of Chlordiazepoxide with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Chlordiazepoxide page.
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