Drug interactions
Chlorzoxazone + Diphenhydramine
Severity: Moderate
Chlorzoxazone and Diphenhydramine: 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
Diphenhydramine is a strongly sedating antihistamine that can increase chlorzoxazone-related drowsiness. Impaired alertness and psychomotor function are likely, especially in older adults.
What this interaction means in plain words
Chlorzoxazone and Diphenhydramine 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.
Chlorzoxazone belongs to Musculoskeletal; Diphenhydramine belongs to Respiratory.
Why it happens
Additive CNS depression.
What to do
Advise against driving and alcohol, and avoid in the elderly where possible. Use a non-sedating antihistamine if suitable.
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
Other interactions of Diphenhydramine
Frequently asked questions
Can I take Chlorzoxazone with Diphenhydramine?
MediHelp rates the interaction as moderate. Chlorzoxazone and Diphenhydramine 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. Diphenhydramine is a strongly sedating antihistamine that can increase chlorzoxazone-related drowsiness. Impaired alertness and psychomotor function are likely, especially in older adults.
How serious is the interaction between Chlorzoxazone and Diphenhydramine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise against driving and alcohol, and avoid in the elderly where possible. Use a non-sedating antihistamine if suitable.
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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