Colestipol Side Effects: What to Expect and When to Call Your Doctor

Colestipol (Colestid) is generally a well-tolerated cholesterol medication, but it does have a distinct side effect profile. Because it works entirely in the digestive tract — it's not absorbed into your body — most side effects are GI-related. Knowing what to expect can help you manage them effectively and recognize when something more serious needs attention.

Does Colestipol Have a Boxed Warning?

No. Colestipol does not carry an FDA boxed warning ("black box warning"). The granule formulation does contain a warning for patients with phenylketonuria because the flavored version contains aspartame, which is metabolized to phenylalanine. If you have phenylketonuria, use the unflavored tablet form instead.

Common Side Effects of Colestipol

The most common side effects of Colestipol are gastrointestinal. They often improve as your body adjusts to the medication. Starting at the lowest dose and increasing gradually helps minimize these effects:

Constipation (most common): The #1 complaint with Colestipol. Most cases are mild and manageable with increased fiber and fluid intake. Starting at the lowest dose (2g once or twice daily) and increasing slowly helps. A stool softener may be recommended if needed.

Gas / flatulence: Very common, especially when starting treatment. Usually decreases over time.

Bloating / abdominal distension: A common early complaint that often improves with continued use.

Nausea: Some patients feel mildly nauseous, especially when starting Colestipol. Taking it with meals may help.

Stomach pain / cramping: Mild abdominal discomfort is relatively common, particularly early in treatment.

Diarrhea: Less common than constipation, but can occur in some patients.

Vomiting: Infrequent; more likely at higher doses.

Headache: Reported by some patients; not clearly related to the drug's GI mechanism.

Managing Constipation on Colestipol

Constipation is the most common reason patients stop taking Colestipol. Here's how to manage it:

Drink at least 8 glasses of water per day

Increase dietary fiber (fruits, vegetables, whole grains, or a fiber supplement like psyllium)

Consider a stool softener (docusate sodium) — ask your doctor first

Start at the lowest dose (2g/day) and increase slowly

If you haven't had a bowel movement in 3 days, contact your care team

Serious Side Effects — When to Call Your Doctor

While Colestipol is generally safe, some side effects require prompt medical attention:

Severe constipation or fecal impaction: Colestipol can cause or worsen severe constipation, especially in patients with pre-existing constipation. Patients with hemorrhoids may find they worsen. Get medical help if you have severe constipation that doesn't resolve.

Abnormal bleeding: Colestipol can reduce vitamin K absorption, leading to hypoprothrombinemia (low clotting factors) and increased bleeding risk. Signs include bloody or black tarry stools, unusual bruising, or blood in urine. This is more likely with long-term use. Tell your doctor immediately.

Fat-soluble vitamin deficiency: Long-term use of Colestipol can reduce absorption of vitamins A, D, E, and K. Your doctor may monitor vitamin levels and recommend supplementation. Take vitamins at least 1 hour before or 4 hours after Colestipol.

Esophageal obstruction (tablets only): Colestipol tablets are large. Rarely, a tablet can become lodged in the esophagus. Always take tablets one at a time with plenty of water. If you feel chest pressure or difficulty swallowing after taking a tablet, seek medical attention.

Elevated triglycerides: Colestipol may raise triglyceride levels in some patients. Your doctor should monitor your full lipid panel during treatment.

Severe allergic reaction: Rare but possible. Symptoms include rash, hives, swelling of the face/lips/tongue/throat, difficulty breathing. Stop taking Colestipol and seek emergency care immediately.

Side Effects of Colestipol Granules vs. Tablets

The side effect profile is similar for both forms of Colestipol. However, the flavored granule form contains aspartame, which is metabolized to phenylalanine — a concern for patients with phenylketonuria (PKU). The tablet form carries an additional (rare) risk of esophageal obstruction if not swallowed correctly. For patients who have difficulty swallowing large pills, the granule form may be preferable.

For more information on drug interactions with Colestipol, see Colestipol Drug Interactions: What to Avoid. To learn more about the medication itself, visit What Is Colestipol? Uses, Dosage, and What You Need to Know.