Drug interactions
Loperamide + Phenytoin
Severity: Minor
Loperamide and Phenytoin: 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
Phenytoin induces P-glycoprotein and CYP enzymes and may lower loperamide exposure, possibly reducing antidiarrheal effect. The change is unlikely to be dangerous.
What this interaction means in plain words
Loperamide and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Loperamide belongs to Gastrointestinal Tract; Phenytoin belongs to Central Nervous System.
Why it happens
Induction of P-glycoprotein and CYP-mediated metabolism of loperamide.
What to do
Assess the antidiarrheal response and adjust loperamide within labeled limits if needed. Consider other causes if diarrhea persists.
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 Loperamide
Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Loperamide with Phenytoin?
MediHelp rates the interaction as minor. Loperamide and Phenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenytoin induces P-glycoprotein and CYP enzymes and may lower loperamide exposure, possibly reducing antidiarrheal effect. The change is unlikely to be dangerous.
How serious is the interaction between Loperamide and Phenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Assess the antidiarrheal response and adjust loperamide within labeled limits if needed. Consider other causes if diarrhea persists.
What other medicines interact with Loperamide?
MediHelp also lists interactions of Loperamide with, for example, Amiodarone, Amisulpride, Anagrelide. The full list is on the Loperamide page.
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