Drug interactions
Clonazepam + Phenobarbital
Severity: Moderate
Clonazepam 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 and clonazepam add to each other's sedative and respiratory depressant effects. Phenobarbital also induces hepatic enzymes and can lower clonazepam concentrations, which may reduce seizure control over time.
What this interaction means in plain words
Clonazepam 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 GABAergic CNS depression plus phenobarbital induction of CYP3A4 increasing clonazepam clearance.
What to do
Monitor sedation and respiratory function, and assess seizure control, adjusting clonazepam dose as needed. Be alert for withdrawal or breakthrough seizures if either drug is changed.
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 Clonazepam
- Calcium / magnesium / potassium / sodium oxybates + Clonazepam Contraindicated
- Clonazepam + Sodium oxybate Contraindicated
- Alfentanil + Clonazepam Major
- Alprazolam + Clonazepam Major
- Amobarbital + Clonazepam Major
- Belladonna and opium + Clonazepam Major
Frequently asked questions
Can I take Clonazepam with Phenobarbital?
MediHelp rates the interaction as moderate. Clonazepam 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 and clonazepam add to each other's sedative and respiratory depressant effects. Phenobarbital also induces hepatic enzymes and can lower clonazepam concentrations, which may reduce seizure control over time.
How serious is the interaction between Clonazepam 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 sedation and respiratory function, and assess seizure control, adjusting clonazepam dose as needed. Be alert for withdrawal or breakthrough seizures if either drug is changed.
What other medicines interact with Clonazepam?
MediHelp also lists interactions of Clonazepam with, for example, Calcium / magnesium / potassium / sodium oxybates, Sodium oxybate, Alfentanil. The full list is on the Clonazepam page.
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