Drug interactions
Fosphenytoin + Lansoprazole
Severity: Minor
Fosphenytoin and Lansoprazole: 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, the active form of fosphenytoin, induces CYP3A4 and CYP2C19 and may lower lansoprazole exposure. Conversely, PPIs may modestly raise phenytoin levels through CYP2C19 inhibition. Clinical effects are usually small.
What this interaction means in plain words
Fosphenytoin and Lansoprazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Fosphenytoin belongs to Central Nervous System; Lansoprazole belongs to Gastrointestinal Tract.
Why it happens
Phenytoin induces hepatic CYP enzymes that metabolize lansoprazole.
What to do
Monitor acid-suppression response and consider a higher lansoprazole dose if needed; monitor phenytoin levels or toxicity signs when starting or stopping the PPI.
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?
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Other interactions of Lansoprazole
- Lansoprazole + Mavacamten Contraindicated
- Lansoprazole + Rilpivirine Contraindicated
- Acalabrutinib + Lansoprazole Major
- Atazanavir + Lansoprazole Major
- Dacomitinib + Lansoprazole Major
- Dasatinib + Lansoprazole Major
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Lansoprazole?
MediHelp rates the interaction as minor. Fosphenytoin and Lansoprazole 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, the active form of fosphenytoin, induces CYP3A4 and CYP2C19 and may lower lansoprazole exposure. Conversely, PPIs may modestly raise phenytoin levels through CYP2C19 inhibition. Clinical effects are usually small.
How serious is the interaction between Fosphenytoin and Lansoprazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor acid-suppression response and consider a higher lansoprazole dose if needed; monitor phenytoin levels or toxicity signs when starting or stopping the PPI.
What other medicines interact with Lansoprazole?
MediHelp also lists interactions of Lansoprazole with, for example, Mavacamten, Rilpivirine, Acalabrutinib. The full list is on the Lansoprazole page.
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