Drug interactions
Montelukast + Phenytoin
Severity: Minor
Montelukast 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 is an inducer of several CYP enzymes, including CYP3A4 and CYP2C family members, and can lower montelukast exposure. Related inducers such as phenobarbital have been shown to reduce montelukast levels, though the clinical effect is usually modest.
What this interaction means in plain words
Montelukast 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.
Montelukast belongs to Respiratory; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4 and CYP2C enzymes, increasing montelukast metabolism.
What to do
No routine dose change is needed. Monitor asthma control and consider therapy adjustment if response declines.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Montelukast and Phenytoin, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Montelukast
- Apalutamide + Montelukast Moderate
- Carbamazepine + Montelukast Moderate
- Deferasirox + Montelukast Moderate
- Enzalutamide + Montelukast Moderate
- Fosphenytoin + Montelukast Moderate
- Gemfibrozil + Montelukast Moderate
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 Montelukast with Phenytoin?
MediHelp rates the interaction as minor. Montelukast 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 is an inducer of several CYP enzymes, including CYP3A4 and CYP2C family members, and can lower montelukast exposure. Related inducers such as phenobarbital have been shown to reduce montelukast levels, though the clinical effect is usually modest.
How serious is the interaction between Montelukast 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: No routine dose change is needed. Monitor asthma control and consider therapy adjustment if response declines.
What other medicines interact with Montelukast?
MediHelp also lists interactions of Montelukast with, for example, Apalutamide, Carbamazepine, Deferasirox. The full list is on the Montelukast page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
