Drug interactions
Cyclosporin + Phenytoin
Severity: Major
Cyclosporin and Phenytoin: major interaction.
Last updated Sources: US FDA label
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 can substantially lower cyclosporine concentrations, risking rejection or loss of immunosuppressive control. Cyclosporine may also alter phenytoin levels in some patients.
What this interaction means in plain words
Cyclosporin 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.
Cyclosporin belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and P-glycoprotein, increasing cyclosporine clearance.
What to do
Use a non-inducing anticonvulsant such as levetiracetam where possible. If phenytoin is required, monitor cyclosporine troughs frequently, increase the dose as needed, and recheck both drug levels when phenytoin is changed.
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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References
Other interactions of Cyclosporin
- Adenovirus types 4 and 7 live + Cyclosporin Contraindicated
- Aliskiren + Cyclosporin Contraindicated
- Bcg vaccine live + Cyclosporin Contraindicated
- Bosentan + Cyclosporin Contraindicated
- Cidofovir + Cyclosporin Contraindicated
- Cyclosporin + Dengue vaccine Contraindicated
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 Cyclosporin with Phenytoin?
MediHelp rates the interaction as major. Cyclosporin 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 can substantially lower cyclosporine concentrations, risking rejection or loss of immunosuppressive control. Cyclosporine may also alter phenytoin levels in some patients.
How serious is the interaction between Cyclosporin 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 a non-inducing anticonvulsant such as levetiracetam where possible. If phenytoin is required, monitor cyclosporine troughs frequently, increase the dose as needed, and recheck both drug levels when phenytoin is changed.
What other medicines interact with Cyclosporin?
MediHelp also lists interactions of Cyclosporin with, for example, Adenovirus types 4 and 7 live, Aliskiren, Bcg vaccine live. The full list is on the Cyclosporin page.
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