Drug Interaction Report

Colesevelam and Niacin: Interaction Details

Name: Colesevelam and Niacin Interaction
Creator: Dr. Brian Staiger, PharmD, BCPS

A pharmacist-reviewed analysis of the Colesevelam and Niacin interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Niacin

Endur-Acin Endur-Amide Niacor Niacor® Niaspan Niaspan® Nicolar® Slo-Niacin

Colesevelam

Welchol WelChol®

Medically reviewed by

Dr. Brian Staiger, PharmD, BCPS

Updated Aug 8, 2026

Editorial policy · Data sources

Interaction severity

Minor

Usually limited clinical impact.

Minor

Moderate

Major

Contraindicated

How we grade severity & evidence

Severity levels

Contraindicated: These should generally not be used together.
Major: Potentially serious — often needs a change or close monitoring.
Moderate: Can be significant — usually manageable with monitoring.
Minor: Usually limited clinical impact.

Evidence grades

Established: Well documented — supported by controlled studies or strong clinical data.
Probable: Good supporting evidence, though not definitively proven.
Suspected: Some evidence suggests this interaction, but it is not well established.
Possible: Limited or conflicting evidence; the interaction may occur.
Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 49 documented Colesevelam interactions, 1 is rated minor — including this one.

Onset

unspecified

Evidence

theoretical

Severity

Minor

What happens

Decreased nicotinic acid exposure

Interaction Deep Dive

Concurrent administration of acid drugs, such as nicotinic acid, with bile acid sequestrants may decrease the bioavailability of nicotinic acid, resulting in decreased nicotinic acid exposure. Nicotinic acid should be administered at least 1 hour before, or at least 4 hours after, bile acid sequestrants¹².

Why it happens (mechanism)

Decreased nicotinic acid absorption

Common questions

Can I take Colesevelam and Niacin together?

Decreased nicotinic acid exposure Always confirm with your pharmacist or prescriber before making any change.

How serious is the Colesevelam and Niacin interaction?

It is rated minor. Usually limited clinical impact.

How quickly could this interaction happen?

The documented onset is "unspecified". The timing of this interaction is not well characterized.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

Does my dose of Colesevelam or Niacin need adjusting while I take them together?
What symptoms should prompt me to call you or my prescriber right away?
Does the timing of my doses matter for this combination?
Is there anything you'd monitor while I'm on both?

References (2)

Product Information: Pelzont oral extended-release tablets, laropiprant nicotinic acid oral extended-release tablets. Merck Sharp & Dohme Ltd. (per EMA), Hoddesdon, Hertfordshire, United Kingdom, 2012.
Product Information: Trevaclyn oral extended-release tablets, laropiprant nicotinic acid oral extended-release tablets. Merck Sharp & Dohme Ltd. (per EMA), Hoddesdon, Hertfordshire, United Kingdom, 2012.

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Niacin

Keep reading about Niacin

All Niacin interactions (24) Niacin drug information

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Colesevelam

Keep reading about Colesevelam

All Colesevelam interactions (49) Colesevelam drug information

Also serious with: Bezafibrate Deferasirox Desogestrel Dienogest

Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Colesevelam + Activated Charcoal Coffee Charcoal European Mandrake Glucomannan Guar Gum Gum Arabic Slippery Elm Tragacanth + 9 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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A message from HelloPharmacist

About our interaction database: depth, not breadth

HelloPharmacist doesn't license one of the big commercial interaction databases, so what you'll find here is not a complete list of every known drug interaction. Instead, each entry is researched, analyzed, and written up individually — documented from the published literature, reviewed by a pharmacist, and cited so you can check every source yourself.

If a combination isn't listed here, it means we haven't documented it yet — never that it's safe. For screening a full medication list, we recommend pairing this site with a comprehensive tool like the Drugs.com Interaction Checker and, most importantly, a review by your own pharmacist. For a deep, plain-English, fully sourced explanation of a specific documented interaction — that's exactly what we built this for.

This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.