Drug interactions
Colesevelam + Fosphenytoin
Severity: Minor
Colesevelam and Fosphenytoin: 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
Colesevelam is a bile acid sequestrant that can bind drugs in the gut and reduce absorption. Fosphenytoin is given parenterally in most settings, and oral phenytoin is the relevant analogue, so any interaction applies only where phenytoin exposure is oral. Reduced phenytoin exposure could lower seizure control.
What this interaction means in plain words
Colesevelam and Fosphenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Colesevelam belongs to Endocrine; Fosphenytoin belongs to Central Nervous System.
Why it happens
Binding of phenytoin in the gastrointestinal tract by the resin reduces oral absorption.
What to do
If oral phenytoin is used, give it at least 4 hours before colesevelam and monitor phenytoin levels and seizure control.
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 Colesevelam and Fosphenytoin, 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 Colesevelam
- Amlodipine-olmesartan-hydrochlorothiazide + Colesevelam Moderate
- Amlodipine-olmesartan + Colesevelam Moderate
- Chenodiol + Colesevelam Moderate
- Cholic acid + Colesevelam Moderate
- Colesevelam + Cyclosporin Moderate
- Colesevelam + Glibenclamide Moderate
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 Colesevelam with Fosphenytoin?
MediHelp rates the interaction as minor. Colesevelam and Fosphenytoin have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Colesevelam is a bile acid sequestrant that can bind drugs in the gut and reduce absorption. Fosphenytoin is given parenterally in most settings, and oral phenytoin is the relevant analogue, so any interaction applies only where phenytoin exposure is oral. Reduced phenytoin exposure could lower seizure control.
How serious is the interaction between Colesevelam and Fosphenytoin?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: If oral phenytoin is used, give it at least 4 hours before colesevelam and monitor phenytoin levels and seizure control.
What other medicines interact with Colesevelam?
MediHelp also lists interactions of Colesevelam with, for example, Amlodipine-olmesartan-hydrochlorothiazide, Amlodipine-olmesartan, Chenodiol. The full list is on the Colesevelam 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.
