Drug interactions
Colesevelam + Levothyroxine
Severity: Moderate
Colesevelam and Levothyroxine: 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
Colesevelam binds levothyroxine in the gut and reduces its absorption when the two are taken together. This can lead to reduced thyroid hormone effect and an elevated TSH.
What this interaction means in plain words
Colesevelam and Levothyroxine 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.
Colesevelam belongs to Endocrine; Levothyroxine belongs to Endocrine.
Why it happens
Bile acid sequestrant binds levothyroxine in the intestinal lumen, reducing absorption.
What to do
Take levothyroxine at least 4 hours before colesevelam. Monitor TSH when the regimen is started or changed.
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 Levothyroxine
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
Frequently asked questions
Can I take Colesevelam with Levothyroxine?
MediHelp rates the interaction as moderate. Colesevelam and Levothyroxine 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. Colesevelam binds levothyroxine in the gut and reduces its absorption when the two are taken together. This can lead to reduced thyroid hormone effect and an elevated TSH.
How serious is the interaction between Colesevelam and Levothyroxine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Take levothyroxine at least 4 hours before colesevelam. Monitor TSH when the regimen is started or changed.
What other medicines interact with Levothyroxine?
MediHelp also lists interactions of Levothyroxine with, for example, Cholestyramine, Sodium iodide i-131, Tiratricol. The full list is on the Levothyroxine page.
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