Loperamide and Quinidine: Drug Interaction Guide
Quick answer: This is a major interaction — avoid combining Loperamide and Quinidine unless specifically directed by your doctor.
How Loperamide interacts with Quinidine
Quinidine inhibits P-glycoprotein at the blood-brain barrier, allowing loperamide to cross into the CNS where it produces opioid effects including respiratory depression, plus both drugs prolong QT.
What you should do
Avoid the combination; if antidiarrhoeal therapy is essential, use bismuth subsalicylate or low-dose loperamide with cardiac monitoring and naloxone availability.
Key facts
Severity
Major — avoid combination
Mechanism
Quinidine inhibits P-glycoprotein at the blood-brain barrier, allowing loperamide to cross into the CNS where it produce...
Action
Avoid the combination; if antidiarrhoeal therapy is essential, use bismuth subsalicylate or low-dose loperamide with car...
Frequently asked questions
Can I take Loperamide and Quinidine together?
No — this combination should generally be avoided. Avoid the combination; if antidiarrhoeal therapy is essential, use bismuth subsalicylate or low-dose loperamide with cardiac monitoring and naloxone availability.
What is the severity of this interaction?
The interaction between Loperamide and Quinidine is classified as Major — avoid combination. Quinidine inhibits P-glycoprotein at the blood-brain barrier, allowing loperamide to cross into the CNS where it produces opioid effects including respiratory depression, plus both drugs prolong QT.
What should I do if I'm prescribed both?
Avoid the combination; if antidiarrhoeal therapy is essential, use bismuth subsalicylate or low-dose loperamide with cardiac monitoring and naloxone availability. Always consult your prescribing clinician — do not stop or change medications without medical guidance.
Last reviewed: by iMedic Medical Editorial Team. Our editorial process.