How long does cholestyramine take to work?

It depends on why you're taking cholestyramine. It might start to lower cholesterol levels after a few weeks, while itching from bile duct problems can improve in about [a week](https://www.ncbi.nlm.nih.gov/books/NBK534089/). Your prescriber will adjust your dose over time based on how well it’s working and how you tolerate it. Talk to your prescriber if you’re concerned about how long this medication is taking to work.

When's the best time to take cholestyramine?

The best time to take cholestyramine is [before or during meals](https://www.goodrx.com/cholestyramine/foods-to-avoid). Be sure to take your [other medications](https://www.goodrx.com/classes/bile-acid-sequestrants/interactions) at least 1 hour before or 4 to 6 hours after cholestyramine to avoid absorption problems. If taking it with meals doesn’t work for your schedule or other medications, talk to your prescriber for guidance.

Is cholestyramine for diarrhea?

Cholestyramine isn't FDA-approved to treat diarrhea. But it can be prescribed [off-label](https://www.goodrx.com/drugs/medication-basics/off-label-drug-prescriptions) for [diarrhea from irritable bowel syndrome (IBS)](https://www.goodrx.com/conditions/irritable-bowel-syndrome/cholestyramine-powder-for-ibs). This is because some types of diarrhea are caused by too much bile acid in your gut. By lowering bile acid levels, cholestyramine can help improve these symptoms.

cholestyramine

Generic Questran

Used for High Cholesterol

Cholestyramine is a bile acid sequestrant used to treat adults with high cholesterol and itching caused by bile duct problems. It comes as a powder in packets or a can that you mix with liquid to make an oral suspension before taking it. You take a dose by mouth 1 to 6 times a day, depending on your condition. The most common side effect is constipation.

Reviewed by:

Robert Chad Hakim, PharmD, BCCCP

Daisy Chau, PharmD

Last reviewed on April 6, 2026

What is Cholestyramine?

What is Cholestyramine used for?

High cholesterol, added onto a heart-healthy diet and exercise
Itching caused by bile duct problems

How Cholestyramine works

Cholestyramine is a bile acid sequestrant. It works by attaching to bile acids in your gut and removing them from your body.

Because of this, your body uses more cholesterol to make new bile acids, which helps lower your cholesterol levels. It also reduces the buildup of bile acids in your skin, which can help relieve itching.

When does Cholestyramine start working?Time passed since treatment started:

HOURS

DAYS

WEEKS

Full effect

MONTHS

Drug facts

Common Brands	Prevalite
Drug Class	Bile acid sequestrant
Controlled Substance Classification	Not a controlled medication
Generic Status	Lower-cost generic available
Availability	Prescription only

Common Brands

Prevalite

Drug Class

Bile acid sequestrant

Controlled Substance Classification

Not a controlled medication

Generic Status

Lower-cost generic available

Availability

Prescription only

Side effects of Cholestyramine

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

Constipation

Less Common Side Effects

Stomach discomfort or pain
Bloating or gas
Nausea
Vomiting
Diarrhea
Burping
Reduced appetite
Fatty stool
Rash

Cholestyramine serious side effects

Contact your healthcare provider immediately if you experience any of the following.

Stomach or intestine problems: no bowel movement, severe stomach pain, black or bloody stools

When do Cholestyramine possible side effects begin and end?

Time passed since treatment started:

HHOURS

DDAYS

WWEEKS

MMONTHS

Mild constipation

Stomach discomfort, bloating, or gas

Nausea or vomiting

Diarrhea

If a line continues to the right, you'll likely keep experiencing this side effect once it starts.

Source: DailyMed

The following Cholestyramine side effects have also been reported

In some animal studies, cholestyramine was found to cause tumors. It is not known whether cholestyramine causes tumors in humans.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Rare

Black, tarry stools

stomach pain (severe) with nausea and vomiting

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

More common

Constipation

Rare

Loss of weight (sudden)

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Heartburn or indigestion

nausea or vomiting

stomach pain

Less common

Belching

bloating

diarrhea

dizziness

headache

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

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Avg retail price

N/A

$5.34

See prices

Pros and cons of Cholestyramine

Pros

Can help lower cholesterol if diet and exercise alone haven’t worked
Works only in your gut so it doesn’t get absorbed into your bloodstream
Powder can be mixed with foods like soup, applesauce, crushed pineapple, or pureed fruit
Available in regular and light (lower sugar) options

Cons

Can cause constipation and stomach discomfort
Interacts with many medications
Might need to be taken multiple times a day
Can reduce absorption of fat-soluble vitamins (A, D, E, and K), especially if taken for a long time

Pharmacist tips for Cholestyramine

Take cholestyramine before or during meals to help it work best.
Take other medications at least 1 hour before or 4 hours after cholestyramine. This helps prevent cholestyramine from blocking how well those medications are absorbed.
Cholestyramine causes constipation. Eating a high-fiber diet and staying well-hydrated can help. Let your care team know if constipation becomes severe or bothersome.
Follow a healthy lifestyle while taking cholestyramine. Eating a heart-healthy diet and exercising regularly can help you get the most out of treatment.
Taking cholestyramine for a long time might lower your levels of fat-soluble vitamins (A, D, E, and K). Your prescriber might recommend vitamin supplements during treatment.
Let your prescriber know if you're pregnant, plan to become pregnant, or breastfeeding. Cholestyramine can affect how your body absorbs important vitamins needed for you and your baby.

How to prepare:

If you have the large can, measure your dose using the scoop that comes with it. Don’t use household spoons because they may not be accurate.
Never take the medication dry. Mix it with liquid before taking it. You can stir it into 2 to 6 ounces of water or another drink, or mix it with foods like soup, applesauce, or crushed pineapple.
Don't sip or hold this medication in your mouth for a long time. This can damage your teeth or change their color.

Common questions about Cholestyramine

While there aren't specific foods that directly interact with how Cholestyramine work, you should try to limit foods that are high in cholesterol. These include fried foods, pizza, and full-fat dairy. It’s best to follow a heart-healthy diet with more fruits, vegetables, whole grains, and lean proteins. Talk to your prescriber or dietitian if you’re unsure what to eat.

It depends on why you're taking Cholestyramine. It might start to lower cholesterol levels after a few weeks, while itching from bile duct problems can improve in about a week. Your prescriber will adjust your dose over time based on how well it’s working and how you tolerate it. Talk to your prescriber if you’re concerned about how long this medication is taking to work.

The best time to take Cholestyramine is before or during meals. Be sure to take your other medications at least 1 hour before or 4 to 6 hours after Cholestyramine to avoid absorption problems. If taking it with meals doesn’t work for your schedule or other medications, talk to your prescriber for guidance.

Cholestyramine isn't FDA-approved to treat diarrhea. But it can be prescribed off-label for diarrhea from irritable bowel syndrome (IBS). This is because some types of diarrhea are caused by too much bile acid in your gut. By lowering bile acid levels, Cholestyramine can help improve these symptoms.

You shouldn’t stop taking Cholestyramine unless you talk to your prescriber first. If you stop it on your own, your cholesterol could go back up or your itching could return. But you should stop taking it and get medical help right away if you have serious side effects, such as unusual bleeding, black or bloody stools, or signs of an allergic reaction like rash, swelling, or trouble breathing.

You can eat right after taking Cholestyramine, since it’s often recommended to take it before or with meals. If you have questions about timing with your meals, your prescriber or pharmacist can help you set a schedule that works best for you.

Both Cholestyramine and colestipol (Colestid) are bile acid sequestrants used to treat high cholesterol. But Cholestyramine can also help treat itching caused by too much bile acid from a blockage. They also come in different forms. Cholestyramine is only available as a powder for oral suspension, whereas colestipol (Colestid) comes as tablets and granules for suspension. Talk to your care team if you have questions about comparing the two.

No, Cholestyramine is only available by a prescription from a healthcare professional.

Risks and warnings for Cholestyramine

Cholestyramine can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.

Higher risk of bleeding

Risk factors: Taking cholestyramine for a long time

Taking cholestyramine for a long time can raise your risk of bleeding because it lowers vitamin K levels, which is an important vitamin that helps stop bleeding. Get medical help if you are throwing up blood, have blood in your urine, or you experience black, tarry stools, or bleeding gums. You might need to be treated with vitamin K supplementation.

Risk of acid imbalance

Risk factors: Taking cholestyramine for a long time | Children | Smaller individuals | Higher dose | Kidney problems | Dehydration | Also taking spironolactone

Very rarely, cholestyramine can affect acid levels in the body. This risk is higher in children, smaller individuals, or people taking higher doses. It can also be more likely if you have kidney problems, are dehydrated, or take certain medications like spironolactone. Talk to your prescriber if you have concerns or notice symptoms like tiredness, confusion, or fast breathing.

Constipation

Cholestyramine can cause or worsen constipation. Your prescriber will usually recommend you start on a low dose and slowly increase it to help lower this risk.

To help prevent constipation, drink plenty of fluids and eat more fiber. Your prescriber might also recommend a stool softener if needed. If constipation gets worse, or if the medication isn’t working well, your prescriber could adjust your dose or consider a different treatment.

Interactions with other medications

Cholestyramine can affect how well your body absorbs other medications. It can bind to certain medications in your gut and make them work less well. Because of this, take your other medications at least 1 hour before or 4 to 6 hours after cholestyramine.

This medication can also affect how your body absorbs vitamins A, D, E, and K. If you use it long term, your prescriber might recommend vitamin supplements.

Caution in people with phenylketonuria (PKU) - light formulation only

Tell your care team if you have phenylketonuria (PKU), a condition where your body can’t break down phenylalanine. The “light” forms of cholestyramine are often sweetened with aspartame, which contains phenylalanine and can be harmful for people with PKU. Regular versions usually don’t contain aspartame. Always check the label or ask your pharmacist which version you have.

Cholestyramine dosage

The average cost for 1 carton of 60 packets of 9g of Cholestyramine is $46.75 with a free GoodRx coupon. This is 24.90% off the average retail price of $62.25.

Can of powder

Dosage	Quantity	Price as low as	Price per unit
378g of 4g/dose	1 can	$29.89	$29.89
348.6g of 4g/dose	1 can	$20.71	$20.71
368.76g of 4g/dose	1 can	$29.27	$29.27
239.4g of 4g/dose	1 can	$32.93	$32.93

Carton

Dosage	Quantity	Price as low as	Price per unit
60 packets of 9g	1 carton	$46.75	$46.75
60 packets of 8.3g	1 carton	$46.75	$46.75

Packet

Dosage	Quantity	Price as low as	Price per unit
9g of 4g/dose	30 packets	$27.90	$0.93

Typical dosage for Cholestyramine

The typical starting dose is 1 pouch or 1 scoopful by mouth once or twice a day with a meal.

Your prescriber might raise the dose up to 2 to 4 pouches or scoopfuls a day divided into two doses, depending on how you're responding to the medication.

The maximum daily dose is 6 pouches or scoopfuls.

Interactions between Cholestyramine and other drugs

Cholestyramine may interact with certain medications or supplements. Always let your doctor and pharmacist know about any other medications or supplements (including prescribed and over-the-counter medications, vitamins, and dietary or herbal supplements) that you are currently taking. The list below does not include all possible drug interactions with Cholestyramine. Please note that only the generic name of each medication is listed below.

More on Cholestyramine interactions

Portrait of a man with his home-cooked meals.
Anchiy/E+ via Getty Images

5 Food and Drinks to Avoid While Taking Cholestyramine

Written by Amy Walsh, MD, MDP

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Aceclofenac
Anisindione
Cephalexin
Cerivastatin
Diclofenac
Dicumarol
Digitoxin
Ezetimibe
Furosemide
Hydrochlorothiazide
Levothyroxine
Meloxicam
Metronidazole
Phenprocoumon
Propranolol
Valproic Acid
Warfarin

How much does Cholestyramine cost?

To access savings, use a GoodRx coupon and pay just a fraction of the retail price.

Prevalite (brand)

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$5.34

(save 92.15%)

Cholestyramine (generic)

GoodRx lowest price

$5.34

(save 95.01%)

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Cholestyramine contraindications

Contraindications are specific health conditions or situations in which a person should not take a medication due to safety concerns. If you have any of the following conditions or if any of the following apply to you, let your healthcare provider know because Cholestyramine will not be safe for you to take.