Skip to Content

Welchol Side Effects

Generic Name: colesevelam

Note: This page contains side effects data for the generic drug colesevelam. It is possible that some of the dosage forms included below may not apply to the brand name Welchol.

In Summary

Common side effects of Welchol include: constipation. Other side effects include: dyspepsia. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to colesevelam: oral powder for suspension, oral tablet

As well as its needed effects, colesevelam (the active ingredient contained in Welchol) may cause unwanted side effects that require medical attention.

Severity: Major

If any of the following side effects occur while taking colesevelam, check with your doctor immediately:

Less common:
  • Anxiety
  • blurred vision
  • chills
  • cold sweats
  • coma
  • confusion
  • congestion
  • cool, pale skin
  • cough
  • depression
  • diarrhea
  • dizziness
  • dry or sore throat
  • fast heartbeat
  • fever
  • general feeling of discomfort or illness
  • headache
  • hoarseness
  • increased hunger
  • joint pain
  • loss of appetite
  • muscle aches or pain
  • nausea
  • nervousness
  • nightmares
  • pounding in the ears
  • runny nose
  • seizures
  • shakiness
  • shivering
  • slow or fast heartbeat
  • slurred speech
  • sweating
  • tender, swollen glands in the neck
  • trouble with sleeping
  • trouble with swallowing
  • unusual tiredness or weakness
  • voice changes
  • vomiting
Incidence not known:
  • Bleeding after defecation
  • darkened urine
  • difficulty with swallowing
  • indigestion
  • pain or discomfort in the chest
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • pressure in the stomach
  • severe stomach pain
  • swelling of the abdominal or stomach area
  • unable to swallow saliva
  • uncomfortable swelling around the anus
  • yellow eyes or skin

Severity: Minor

Some colesevelam side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Acid or sour stomach
  • belching
  • bloating
  • constipation
  • full or bloated feeling
  • heartburn
  • pain or cramping in the abdomen or stomach
  • stomach discomfort, upset, or pain
Less common:
  • Lack or loss of strength
  • sneezing
  • stuffy nose

For Healthcare Professionals

Applies to colesevelam: oral powder for reconstitution, oral tablet


Cardiovascular side effects including hypertension, myocardial infarction, aortic stenosis, and bradycardia have been reported in 3% of patients.


Gastrointestinal side effects have included flatulence (12%), constipation (8.7% to 11%), dyspepsia (3.9% to 8%), diarrhea (5%), and nausea (3% to 4%). Bowel obstruction (in patients with a history of bowel obstruction or resection), dysphagia or esophageal obstruction (occasionally requiring medical intervention), fecal impaction, pancreatitis, abdominal distension, exacerbation of hemorrhoids, and increased transaminases have been reported in postmarketing experience.[Ref]


Immunologic side effects have included infection (10%).[Ref]


In the lipid-lowering trials, 807 patients received at least one dose of colesevelam (the active ingredient contained in Welchol) therapy (total exposure 199 patient-years). In the type 2 diabetes trials, 566 patients received at least one dose of colesevelam therapy (total exposure 209 patient years). In clinical trials for the reduction of LDL-C, 68% of patients receiving colesevelam therapy versus 64% of patients receiving placebo reported an adverse event. In clinical trials of type 2 diabetes, 60% of patients receiving colesevelam therapy versus 56% of patients receiving placebo reported an adverse event.[Ref]


Respiratory side effects have included nasopharyngitis (4%), pharyngitis (3%), rhinitis (3%), sinusitis (2%), and increased cough (2%).[Ref]


Musculoskeletal side effects have included myalgia (2%).[Ref]


Metabolic side effects have included hypoglycemia (3%). Hypertriglyceridemia has been reported in postmarketing experience.[Ref]

Nervous system

Nervous system side effects have included headache (6%), pain (6%), and back pain (3%).


Other side effects have included abdominal pain (5%), accidental injury (4%), asthenia (4%), and flu syndrome (3%).


1. "Product Information. Welchol (colsevelam)" Southwood Pharmaceuticals Inc, Lake Forest, CA.

2. Davidson MH, Dillon MA, Gordon B, Jones P, Samuels J, Weiss S, Isaacsohn J, Toth P, Burke SK "Colesevelam hydrochloride (Cholestagel) - A new, potent bile acid sequestrant associated with a low incidence of gastrointestinal side effects." Arch Intern Med 159 (1999): 1893-900

It is possible that some side effects of Welchol may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.