Drug interactions
Ketoconazole + Loperamide
Severity: Major
Ketoconazole and Loperamide: major 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
Ketoconazole substantially increases loperamide plasma concentrations and can enhance central opioid effects. Elevated loperamide levels also raise the risk of QT prolongation and arrhythmia.
What this interaction means in plain words
Ketoconazole and Loperamide can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Ketoconazole belongs to Anti Fungals; Loperamide belongs to Gastrointestinal Tract.
Why it happens
Ketoconazole inhibits CYP3A4 and P-glycoprotein, decreasing loperamide metabolism and efflux.
What to do
Avoid the combination where possible, or keep loperamide at the lowest dose and briefly. Monitor ECG and for CNS depression or palpitations.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Loperamide
Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Ketoconazole with Loperamide?
MediHelp rates the interaction as major. Ketoconazole and Loperamide can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Ketoconazole substantially increases loperamide plasma concentrations and can enhance central opioid effects. Elevated loperamide levels also raise the risk of QT prolongation and arrhythmia.
How serious is the interaction between Ketoconazole and Loperamide?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination where possible, or keep loperamide at the lowest dose and briefly. Monitor ECG and for CNS depression or palpitations.
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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