Learn about common and serious Welchol side effects, how to manage them, and when you should contact your doctor. Updated for 2026 with practical tips.
Welchol (Colesevelam) is a bile acid sequestrant used to lower LDL cholesterol and help manage type 2 diabetes. Like all medications, it can cause side effects. The good news is that most Welchol side effects are mild and manageable. In this guide, we'll cover what to expect, how to handle common issues, and when you should call your doctor.
Welchol works by binding to bile acids in your intestines and preventing your body from reabsorbing them. This process happens entirely in your digestive system — Welchol is not absorbed into your bloodstream. Because of this, most side effects are related to your stomach and intestines.
For a more detailed explanation, see our article: How Does Welchol Work? Mechanism of Action Explained.
These side effects are the most frequently reported by patients taking Welchol. They are usually mild and often improve as your body adjusts to the medication.
Constipation is the most common side effect of Welchol. Bile acid sequestrants can slow down your digestive system, making bowel movements less frequent or harder to pass.
What you can do:
Flatulence and bloating are very common when starting Welchol. Your digestive system needs time to adjust to the way the medication changes bile acid levels in your gut.
What you can do:
Some patients experience nausea, especially when first starting Welchol. Taking the medication with a full meal (as directed) can help reduce this.
Welchol can sometimes cause indigestion or a burning feeling in your upper stomach. If this is bothersome, talk to your doctor about whether an antacid is appropriate.
Some patients report headaches, muscle aches, or general tiredness. These side effects are less common and are usually mild.
While serious side effects from Welchol are rare, they do happen. Contact your doctor right away if you experience any of the following:
If you develop intense stomach pain — with or without nausea and vomiting — this could be a sign of a serious problem. Don't ignore severe belly pain, especially if it comes on suddenly.
In rare cases, Welchol can contribute to a bowel obstruction. Symptoms include:
If you have a history of bowel obstruction, Welchol is contraindicated (you should not take it). Make sure your doctor knows your full medical history.
Welchol can raise your triglyceride levels. Your doctor should check your triglyceride levels before starting Welchol and periodically while you're taking it. If your triglycerides were already above 300 mg/dL, your doctor will monitor you closely. Welchol should not be used if your triglycerides are above 500 mg/dL.
Although rare, some people may have an allergic reaction to Welchol. Seek immediate medical attention if you notice:
Most patients tolerate Welchol well. The GI side effects (constipation, gas) are the most common complaints, but they tend to be mild and improve over time. Compared to some other cholesterol medications, Welchol has a distinct advantage: it doesn't enter your bloodstream, which means it's less likely to cause systemic side effects like liver problems or muscle damage.
If you're concerned about side effects, talk to your doctor before stopping Welchol. Suddenly stopping a cholesterol or diabetes medication can affect your health. Your doctor can help you weigh the benefits against any side effects you're experiencing.
Welchol is approved for children ages 10-17 with familial heterozygous hypercholesterolemia. Side effects in children are similar to adults, with GI symptoms being the most common.
If you have trouble swallowing the large tablets, Welchol is also available as an oral suspension (powder mixed with liquid) and chewable bars. Talk to your doctor about switching forms if the tablets are a problem.
The oral suspension form of Welchol contains aspartame, which is a source of phenylalanine. If you have PKU, let your doctor know before using the suspension form.
Contact your doctor if:
Your doctor may adjust your dose, switch you to a different form of Welchol, or recommend an alternative medication. To learn about other options, read our guide: Alternatives to Welchol.
For general information about Welchol, including dosage and how to take it, see: What Is Welchol? Uses, Dosage, and What You Need to Know.
You focus on staying healthy. We'll handle the rest.
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