Drug interactions
Chlorpheniramine + Thioridazine
Severity: Moderate
Chlorpheniramine and Thioridazine: 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 drugs cause drowsiness and have anticholinergic activity. Together they can cause marked sedation, confusion, dry mouth, urinary retention and blurred vision, especially in older patients. First-generation antihistamines have also been associated with QT effects at high exposure.
What this interaction means in plain words
Chlorpheniramine and Thioridazine 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.
Chlorpheniramine belongs to Respiratory; Thioridazine belongs to Central Nervous System.
Why it happens
Additive H1 antagonism and muscarinic blockade producing CNS depression and anticholinergic effects.
What to do
Prefer a non-sedating antihistamine in patients taking thioridazine. If both are used, monitor for oversedation and anticholinergic effects.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Chlorpheniramine
Frequently asked questions
Can I take Chlorpheniramine with Thioridazine?
MediHelp rates the interaction as moderate. Chlorpheniramine and Thioridazine 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 drugs cause drowsiness and have anticholinergic activity. Together they can cause marked sedation, confusion, dry mouth, urinary retention and blurred vision, especially in older patients. First-generation antihistamines have also been associated with QT effects at high exposure.
How serious is the interaction between Chlorpheniramine and Thioridazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-sedating antihistamine in patients taking thioridazine. If both are used, monitor for oversedation and anticholinergic effects.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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