Drug interactions
Nifedipine + Phenytoin
Severity: Major
Nifedipine and Phenytoin: 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
Phenytoin induces CYP3A4 and markedly reduces nifedipine exposure, which can cause loss of antihypertensive or antianginal effect. Nifedipine may also modestly raise phenytoin levels in some patients.
What this interaction means in plain words
Nifedipine and Phenytoin 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.
Nifedipine belongs to Cardiovascular; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing nifedipine metabolism, while nifedipine may slightly inhibit phenytoin metabolism.
What to do
Use an alternative antihypertensive not dependent on CYP3A4 where possible. If combined, titrate nifedipine to blood pressure response and monitor phenytoin concentrations.
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 Nifedipine
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 Nifedipine with Phenytoin?
MediHelp rates the interaction as major. Nifedipine and Phenytoin 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. Phenytoin induces CYP3A4 and markedly reduces nifedipine exposure, which can cause loss of antihypertensive or antianginal effect. Nifedipine may also modestly raise phenytoin levels in some patients.
How serious is the interaction between Nifedipine and Phenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use an alternative antihypertensive not dependent on CYP3A4 where possible. If combined, titrate nifedipine to blood pressure response and monitor phenytoin concentrations.
What other medicines interact with Nifedipine?
MediHelp also lists interactions of Nifedipine with, for example, Amifostine, Amlodipine-benazepril, Apalutamide. The full list is on the Nifedipine page.
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