Drug interactions
Clemastine + Phenobarbital
Severity: Moderate
Clemastine 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
Both agents depress the CNS, so together they can produce excess drowsiness, slowed reaction time and impaired cognition. Older patients and those on higher phenobarbital doses are at greater risk.
What this interaction means in plain words
Clemastine 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 CNS depression from H1-antihistamine sedation and barbiturate potentiation of GABA-A activity.
What to do
Monitor for oversedation and lower doses if it occurs. Counsel patients to avoid driving, alcohol and other sedatives.
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 Clemastine
Frequently asked questions
Can I take Clemastine with Phenobarbital?
MediHelp rates the interaction as moderate. Clemastine 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. Both agents depress the CNS, so together they can produce excess drowsiness, slowed reaction time and impaired cognition. Older patients and those on higher phenobarbital doses are at greater risk.
How serious is the interaction between Clemastine 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 oversedation and lower doses if it occurs. Counsel patients to avoid driving, alcohol and other sedatives.
What other medicines interact with Clemastine?
MediHelp also lists interactions of Clemastine with, for example, Alfentanil, Benzhydrocodone / acetaminophen, Buprenorphine buccal. The full list is on the Clemastine page.
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