Cholestyramine for Diarrhea

Cholestyramine is a medication usually prescribed to lower cholesterol. However, cholestyramine is sometimes also used to treat chronic diarrhea because it affects bile acid, a substance created in the liver that can cause diarrhea.

Since it's a drug approved by the Food and Drug Administration (FDA) for a different medical need, prescribing it to help with diarrhea is called an "off-label" use.

This article explains how cholestyramine helps with diarrhea and what you need to know about it before you take it, including proper dosage and side effects.

What Is Cholestyramine? 

Cholestyramine belongs to a class of drugs known as bile acid binders or sequestrants.

Cholestyramine is available as a generic drug and typically comes in a powder that can be added to beverages.

Uses

If you have high cholesterol, cholestyramine's ability to reduce bile acid has a special effect. It triggers a reaction that tells your body to convert blood cholesterol into bile acids. That results in less cholesterol in your blood.

Cholestyramine is used along with dietary changes to lower low-density lipoproteins (LDL). This so-called "bad" cholesterol raises your risk of heart disease.

Cholestyramine is also prescribed to relieve pruritus (itchiness) which can occur when the flow of bile between the liver and intestines is blocked. This causes a build-up of bile and a condition known as cholestasis.

Off-Label Uses for Diarrhea

Bile acids are produced in the liver and stored in the gallbladder. After they help with digestion in the intestines, the unused bile acids get reabsorbed and sent back to the liver to be recycled. Normally, only a small portion makes its way through the intestines and colon.

If your body releases extra bile acids that spill into the colon, you have a condition known as bile acid diarrhea (BAD), also called bile acid malabsorption (BAM). The excess bile acid in the colon causes loose and watery stools.

Cholestyramine helps stop the problems caused by too much bile acid. It attaches itself to bile acids within the digestive tract to ensure that the extra bile acids pass out of the body, which relieves symptoms of diarrhea.

Other Off-Label Uses

Cholestyramine may also be prescribed for Graves' disease, an autoimmune disorder that leads to an overproduction of thyroid hormones. Cholestyramine has been used for people with Graves' disease who have high levels of thyroid hormones in the blood.

When Should You Take Cholestyramine?

Your doctor may test a stool sample to check for bile acids. Sometimes, doctors prescribe cholestyramine without additional tests if they suspect BAM just to see if it helps with diarrhea.

When diagnosing BAM, doctors may classify the disorder into one of four different categories:

• Ileal diseases, including Crohn's disease, which prevents reabsorption of bile acids from the terminal ileum, the end of the small intestine that intersects with the colon
• Celiac disease, diseases of the pancreas such as chronic pancreatitis, or other disorders related to poor absorption of nutrients during digestion
• Diarrhea-predominant irritable bowel syndrome (IBS-D) with no clear underlying cause
• Excessive bile acid that occurs in some people who have high levels of triglycerides (a type of body fat) and in people who take the diabetes drug metformin

Reasons to Avoid

For certain people, cholestyramine is not a safe or effective treatment for diarrhea. It should not be used if you're allergic to the medication or if your bile duct is completely blocked, which means that no bile is being released into your intestines.

Phenylketonuria

Phenylketonuria (PKU) is a genetic disorder that makes you unable to fully break down the protein phenylalanine. Cholestyramine contains phenylalanine. Since people with PKU have to avoid this protein, the sequestrant can be dangerous for them.

When taking cholestyramine, ask your doctor if you need to take vitamin supplements since the drug makes it harder to absorb vitamins from food in your diet.

Dosage

Cholestyramine for diarrhea is typically given as an initial dose of 4 g a day, and it may be increased as needed to 4 g taken two to four times per day.

Cholestyramine is taken as a dissolvable powder or a chewable bar when used to treat high cholesterol. A dose of 4 to 7 grams (g) of medication (often the equivalent of 5 to 9 g of powder) may be taken one to six times a day as instructed by your doctor. The powder comes in a carton of individual packets or in a canister with a serving scoop.

When used to treat pruritus associated with a partial bile obstruction or Graves' disease, a dose of 4 g may be given up to three times per day for itching or four times a day for Graves' disease.

How to Take

To use cholestyramine effectively, follow these guidelines.

• Take this medication before a meal or prior to bed.
• Mix the powder form with 2 to 6 ounces of non-carbonated fluids such as water or juice.
• Drink the medication quickly instead of slowly sipping it.
  
• Try to take other medications or vitamins at least 1 hour before or 4 hours after taking cholestyramine since it can interfere with their absorption.
• If you use the bar form, be sure to drink plenty of water.

Side Effects

Side effects are more likely to occur in people over age 60, but you should be aware of possible problems no matter what your age. If you experience any of the following side effects, discuss them with your doctor.

Common

The most common side effects of cholestyramine are digestive problems. These may go away as your body gets used to the medication. They include:

• Constipation
• Abdominal discomfort or pain

The following side effects may also occur:

• Bloating
• Diarrhea
• Dizziness
• Gas
• Headache   
• Extra bleeding due to vitamin K deficiency
• Vitamin A or D deficiencies
• Osteoporosis
• Hyperchloremic acidosis, especially in children
• Rash or irritated skin or tongue

Severe

Seek medical help if you experience signs of an allergic reaction, such as hives, and call your healthcare provider immediately if you have:

• Rectal bleeding
• Severe abdominal pain
• Sudden loss of weight
• Vomiting
• Rectal bleeding or black stools

Warnings and Interactions

Tell your doctor if you're pregnant or breastfeeding or have any chronic health problems such as diabetes, kidney disease, or heart or blood vessel disease.

Cholestyramine can delay or reduce the absorption of other oral medications. Be sure to tell your doctor what other medications you are currently taking, such as:

• Oral birth control pills or hormone therapy
• Penicillin G
• Phenobarbital
• Phenylbutazone
• Warfarin
• Thyroid drugs
• Oral phosphate supplements
• Thiazide diuretics
• Propranolol
• Tetracycline
• Digoxin

Summary

The FDA has approved cholestyramine to help lower LDL cholesterol. It’s effective because it gets rid of bile acid, which forces the body to use more bile acid (that it makes from bad cholesterol). Cholestyramine's bile acid-eliminating ability also helps stop diarrhea caused by too much bile acid in the intestines,

Thus, doctors can prescribe the drug to patients who don’t need to lower their cholesterol but still want to reduce bile acid. 

Before prescribing the medication, though, your doctor needs to consider if cholestyramine might interact with other medications and whether you have conditions that would be aggravated by the drug (such as PKU). 

A Word From Verywell

In the end, it’s important to know that cholestyramine can allow you to manage diarrhea symptoms, but it won’t cure underlying disorders that might be causing the bile acid problems. You will need to work with your doctor to identify other symptoms and get proper tests to diagnose and treat the root cause of diarrhea.