Drug interactions
Belladonna and opium + Clemastine
Severity: Moderate
Belladonna and opium and Clemastine: 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
Clemastine is a sedating antihistamine and the opium component is an opioid, so combining them increases drowsiness and impairs psychomotor performance. Belladonna alkaloids add anticholinergic effects such as dry mouth, urinary retention and constipation, and respiratory depression is possible at higher opioid doses.
What this interaction means in plain words
Belladonna and opium and Clemastine 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 the opioid and the sedating antihistamine, plus additive anticholinergic effects from clemastine and belladonna.
What to do
Use the lowest effective doses and warn the patient about driving and operating machinery. Monitor for excessive sedation, respiratory depression, urinary retention and constipation, especially in older adults.
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 Belladonna and opium with Clemastine?
MediHelp rates the interaction as moderate. Belladonna and opium and Clemastine 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. Clemastine is a sedating antihistamine and the opium component is an opioid, so combining them increases drowsiness and impairs psychomotor performance. Belladonna alkaloids add anticholinergic effects such as dry mouth, urinary retention and constipation, and respiratory depression is possible at higher opioid doses.
How serious is the interaction between Belladonna and opium and Clemastine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the lowest effective doses and warn the patient about driving and operating machinery. Monitor for excessive sedation, respiratory depression, urinary retention and constipation, especially in older adults.
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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