Drug interactions
Chlordiazepoxide-clidinium + Promethazine
Severity: Moderate
Chlordiazepoxide-clidinium and Promethazine: 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
Promethazine is a strongly sedating antihistamine with anticholinergic activity. With chlordiazepoxide it can produce marked drowsiness, impaired psychomotor performance and respiratory depression, and clidinium adds to anticholinergic effects.
What this interaction means in plain words
Chlordiazepoxide-clidinium and Promethazine 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-clidinium belongs to Gastrointestinal Tract; Promethazine belongs to Respiratory.
Why it happens
Additive CNS depression (H1 antagonism plus GABA-A potentiation) and additive anticholinergic effects.
What to do
Use the lowest effective doses and monitor sedation, respiration and anticholinergic effects. Avoid in older adults where possible and counsel on driving.
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-clidinium
- Alfentanil + Chlordiazepoxide-clidinium Major
- Alprazolam + Chlordiazepoxide-clidinium Major
- Amobarbital + Chlordiazepoxide-clidinium Major
- Belladonna and opium + Chlordiazepoxide-clidinium Major
- Benzhydrocodone / acetaminophen + Chlordiazepoxide-clidinium Major
- Brexanolone + Chlordiazepoxide-clidinium Major
Other interactions of Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Frequently asked questions
Can I take Chlordiazepoxide-clidinium with Promethazine?
MediHelp rates the interaction as moderate. Chlordiazepoxide-clidinium and Promethazine 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. Promethazine is a strongly sedating antihistamine with anticholinergic activity. With chlordiazepoxide it can produce marked drowsiness, impaired psychomotor performance and respiratory depression, and clidinium adds to anticholinergic effects.
How serious is the interaction between Chlordiazepoxide-clidinium and Promethazine?
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 monitor sedation, respiration and anticholinergic effects. Avoid in older adults where possible and counsel on driving.
What other medicines interact with Chlordiazepoxide-clidinium?
MediHelp also lists interactions of Chlordiazepoxide-clidinium with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Chlordiazepoxide-clidinium page.
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