Cholestyramine resin belongs to the class of medications known as bile acid sequestrants. When used along with changes to diet and exercise, this medication helps to reduce cholesterol levels in the blood. It works by binding to cholesterol-like substances called bile acids in the intestines and preventing them from being absorbed into the body.

Cholestyramine resin may be used for symptomatic control of bile-induced diarrhea due to short bowel syndrome and may also be used to relieve itchiness associated with partial blockage of bile ducts.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of cholestyramine resin is 4 g (1 packet) 1 to 6 times daily depending on circumstances.

The powder must be mixed with water (120 mL to 180 mL for the regular powder and 60 mL to 90 mL for the "light" powder) or other fluids (milk, fruit juice, or other non-carbonated beverage). It may also be mixed with watery soups or pulpy fruits with a high moisture content such as applesauce or crushed pineapple.

Other medications should be taken at least one hour before or 4 to 6 hours after cholestyramine resin. Cholestyramine should never be taken in its dry form. The colour of cholestyramine resin may vary somewhat from batch to batch but this does not affect the performance of the medication.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and protect it from moisture. Keep it out of the reach of children.

Do not take cholestyramine resin if you:

• are allergic to cholestyramine resin or to any of the ingredients of the medication
• have bile ducts that are completely blocked

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• bloating
• constipation
• diarrhea
• gas
• heartburn or indigestion
• irritation of tongue
• irritation of skin around the genitals and rectum
• loss of appetite
• nausea or vomiting
• rash
• skin irritation
• stomach pain

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• black, tarry stools
• stomach pain (severe) with nausea and vomiting

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Bleeding tendency: Long-term use of cholestyramine resin may increase bleeding tendency due to vitamin K deficiency.

Constipation: Cholestyramine resin may produce or worsen constipation. Fecal impaction (a large mass of stool that may be lodged in the colon) and worsening of hemorrhoids may occur.

Nutrition: Cholestyramine resin can absorb fat-soluble vitamins such as vitamins A, D, E, and K from the digestive system, preventing them from being absorbed into the body. People who use cholestyramine for a long period of time are at an increased risk of not getting enough of these nutrients. Talk to your doctor about whether supplements may be beneficial.

Pregnancy: Since cholestyramine resin is not absorbed by the body, it is not expected to harm the baby during pregnancy when taken in recommended doses. However, this medication may reduce the absorption of fat-soluble vitamins (vitamins A, D, E, and K), which should be taken into account when planning for vitamin intake during pregnancy.

Breast-feeding: Breast-feeding mothers should exercise caution when taking cholestyramine resin. The possible lack of proper vitamin absorption may have an effect on breast-feeding infants.

Children: The effects of this medication on children are not known. Experts recommend, however, that treatment with this medication be considered for children 10 years or older who have tried diet therapy but still have unacceptably high serum cholesterol levels. In certain situations where a young child has extremely high serum cholesterol levels, treatment with medication may even start before 10 years of age. If a child starts treatment with this medication, a carefully planned diet should be followed in order to obtain best results.

Seniors: People over 60 years of age may be more likely to experience gastrointestinal (stomach and intestines) side effects.

There may be an interaction between cholestyramine resin and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.