Drug interactions
Propantheline + Thioridazine
Severity: Moderate
Propantheline 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 have antimuscarinic activity, so combining them adds to dry mouth, constipation, urinary retention, blurred vision and confusion. Reduced gut motility may also alter oral absorption of thioridazine, and elderly patients are especially vulnerable to anticholinergic toxicity.
What this interaction means in plain words
Propantheline 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.
Why it happens
Additive peripheral and central muscarinic receptor blockade, with possible altered oral absorption from slowed gastrointestinal motility.
What to do
Monitor for anticholinergic effects such as urinary retention, constipation, confusion and tachycardia, and reduce the propantheline dose or choose an alternative if they appear. Avoid in patients with glaucoma, ileus or prostatic obstruction.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Propantheline and Thioridazine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Propantheline with Thioridazine?
MediHelp rates the interaction as moderate. Propantheline 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 have antimuscarinic activity, so combining them adds to dry mouth, constipation, urinary retention, blurred vision and confusion. Reduced gut motility may also alter oral absorption of thioridazine, and elderly patients are especially vulnerable to anticholinergic toxicity.
How serious is the interaction between Propantheline 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: Monitor for anticholinergic effects such as urinary retention, constipation, confusion and tachycardia, and reduce the propantheline dose or choose an alternative if they appear. Avoid in patients with glaucoma, ileus or prostatic obstruction.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
