Drug interactions
Orlistat + Phenytoin
Severity: Moderate
Orlistat and Phenytoin: moderate 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
Orlistat has been associated with reduced antiepileptic drug levels and seizures in case reports. The lower exposure may result in loss of seizure control.
What this interaction means in plain words
Orlistat and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Orlistat belongs to Miscellaneous; Phenytoin belongs to Central Nervous System.
Why it happens
Orlistat may reduce the absorption of lipophilic phenytoin from the gut; the mechanism is not firmly established.
What to do
Monitor phenytoin levels and seizure frequency when starting or stopping orlistat. Consider avoiding orlistat in patients with poorly controlled epilepsy.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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
Other interactions of Orlistat
- Cyclosporine + Orlistat Major
- Cyclosporin + Orlistat Major
- Orlistat + Triheptanoin Major
- Amiodarone + Orlistat Moderate
- Beta carotene + Orlistat Moderate
- Carbamazepine + Orlistat Moderate
Frequently asked questions
Can I take Orlistat with Phenytoin?
MediHelp rates the interaction as moderate. Orlistat and Phenytoin can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Orlistat has been associated with reduced antiepileptic drug levels and seizures in case reports. The lower exposure may result in loss of seizure control.
How serious is the interaction between Orlistat and Phenytoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor phenytoin levels and seizure frequency when starting or stopping orlistat. Consider avoiding orlistat in patients with poorly controlled epilepsy.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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