Drug interactions
Nevirapine + Phenytoin
Severity: Major
Nevirapine 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 is a strong enzyme inducer and can substantially lower nevirapine concentrations, risking virological failure and resistance. Nevirapine may also alter phenytoin levels unpredictably.
What this interaction means in plain words
Nevirapine 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.
Nevirapine belongs to Anti Virals; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and CYP2B6, accelerating nevirapine metabolism.
What to do
Avoid if possible by choosing a non-inducing anticonvulsant such as levetiracetam; if combined, monitor viral load, nevirapine levels and phenytoin levels.
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 Nevirapine
- Elbasvir / grazoprevir + Nevirapine Contraindicated
- Nevirapine + Ranolazine Contraindicated
- Nevirapine + St john's wort Contraindicated
- Abemaciclib + Nevirapine Major
- Acalabrutinib + Nevirapine Major
- Amobarbital + Nevirapine Major
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 Nevirapine with Phenytoin?
MediHelp rates the interaction as major. Nevirapine 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 is a strong enzyme inducer and can substantially lower nevirapine concentrations, risking virological failure and resistance. Nevirapine may also alter phenytoin levels unpredictably.
How serious is the interaction between Nevirapine 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: Avoid if possible by choosing a non-inducing anticonvulsant such as levetiracetam; if combined, monitor viral load, nevirapine levels and phenytoin levels.
What other medicines interact with Nevirapine?
MediHelp also lists interactions of Nevirapine with, for example, Elbasvir / grazoprevir, Ranolazine, St john's wort. The full list is on the Nevirapine page.
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