Cholestyramine: What it does and how to use it safely

Cholestyramine is a bile acid sequestrant that acts in your gut to lower LDL cholesterol and to trap bile acids that cause diarrhea or itching from liver disease. It isn't absorbed into the bloodstream — it works locally inside your intestine. That makes it useful when other drugs aren’t tolerated or when bile salts are the problem.

Where cholestyramine helps

Most people hear about cholestyramine for cholesterol. It can lower LDL cholesterol by a modest amount, so doctors sometimes add it when statins alone don’t hit targets. It’s also a go-to for:

• Diarrhea from bile acid malabsorption — it soaks up excess bile acids that irritate the colon.
• Itching (pruritus) in some liver conditions — by reducing bile acids in the gut that can build up and cause itching.

Expect effects on cholesterol to appear over weeks. If you’re using it for diarrhea or itching, relief can show up sooner.

How to take it, common side effects, and key interactions

Cholestyramine usually comes as a powder you mix with water, juice, or soft foods. Follow your prescription for dose — common starting amounts are one scoop (4 g) once or twice a day, increasing if needed. Mix well, swallow right away, and don’t inhale the powder (it’s dusty).

Timing matters. Cholestyramine binds other drugs and some vitamins. To avoid that, take other oral medicines at least 1 hour before cholestyramine or 4–6 hours after. That includes thyroid pills, warfarin, digoxin, and many others. Ask your pharmacist for a list if you take multiple meds.

Side effects are mostly gut-related: constipation, bloating, gas, and sometimes nausea. To reduce constipation, drink more fluids, add fiber-rich foods, and stay active. If constipation is severe or you have belly pain, call your provider. Long-term use can lower absorption of fat-soluble vitamins (A, D, E, K), so check vitamin levels if you’re on it for months.

Special notes: if you have a bowel obstruction, trouble swallowing, or severe constipation, cholestyramine isn’t safe. Pregnant or breastfeeding? Talk with your doctor — choices depend on your condition and alternatives. Keep the powder in a dry, closed container at room temperature.

Questions to ask your prescriber: Will this replace or add to current meds? How long until we reassess? Do I need blood tests or vitamin checks? These simple questions help you avoid surprises and get the best results from treatment.

Cholestyramine can be very helpful when used right. Use correct timing with other drugs, watch for constipation, and stay in touch with your healthcare team if anything feels off.