Drug interactions
Promethazine + Tiotropium
Severity: Minor
Promethazine and Tiotropium: minor 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 has anticholinergic properties that may add to those of inhaled tiotropium, and this can cause dry mouth, urinary retention, constipation and blurred vision. Systemic exposure from tiotropium is low, so effects are usually modest.
What this interaction means in plain words
Promethazine and Tiotropium have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Promethazine belongs to Respiratory; Tiotropium belongs to Respiratory.
Why it happens
Additive muscarinic receptor antagonism.
What to do
Monitor for anticholinergic symptoms, especially urinary retention and narrow-angle glaucoma symptoms in at-risk patients.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Promethazine
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
- Amiodarone + Promethazine Major
- Amisulpride + Promethazine Major
Other interactions of Tiotropium
Frequently asked questions
Can I take Promethazine with Tiotropium?
MediHelp rates the interaction as minor. Promethazine and Tiotropium have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Promethazine has anticholinergic properties that may add to those of inhaled tiotropium, and this can cause dry mouth, urinary retention, constipation and blurred vision. Systemic exposure from tiotropium is low, so effects are usually modest.
How serious is the interaction between Promethazine and Tiotropium?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for anticholinergic symptoms, especially urinary retention and narrow-angle glaucoma symptoms in at-risk patients.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Ibutilide, Pimozide, Thioridazine. The full list is on the Promethazine page.
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