How the interaction occurs:
Colesevelam may bind to phenytoin in your GI tract, preventing your body from absorbing the medicine.
What might happen:
The amount of phenytoin in your blood may decrease and it may not work as well.
What you should do about this interaction:
Let your healthcare professionals (e.g. doctor or pharmacist) know that you are taking these medicines together. You should time your medicines so that you take your phenytoin 4 hours or more before your colesevelam. If you have any questions about how to take your medicines, ask your pharmacist. Your doctor may want to check the amount of phenytoin in your blood while you are taking these medicines together. Let your doctor know right away if you have a seizure.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.Reference:1.Welchol (colesevelam hydrochloride) US prescribing information. Daiichi Sankyo, Inc. July, 2012.