Welchol (colesevelam hydrochloride) is a prescription drug that’s used to treat high cholesterol and type 2 diabetes. Welchol can cause side effects that range from mild to serious. Examples include nausea, constipation, and low blood sugar.

Specifically, Welchol is used to treat:

The active ingredient in Welchol is colesevelam hydrochloride. (An active ingredient is what makes a drug work.) Welchol comes as a tablet that you swallow and as a powder that you dissolve in water and drink.

Keep reading to learn about the common, mild, and serious side effects that Welchol can cause. For a general overview of the drug, including details about its uses, see this article.

Some people may experience mild or serious side effects during their Welchol treatment. Examples of Welchol’s commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Examples of mild side effects that have been reported with Welchol include:

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. Some may be easily managed, too. But if you have any symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop taking Welchol unless your doctor recommends it.

Welchol may cause mild side effects other than the ones listed above. See the Welchol prescribing information for details.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Welchol, visit MedWatch.

Some people may experience serious side effects during their Welchol treatment. Serious side effects that have been reported with this drug include:

  • blockage in the intestines
  • high levels of triglycerides (a type of fat), which could lead to acute pancreatitis (swelling of the pancreas)
  • low blood sugar* (in people with type 2 diabetes), which is often mild but may be severe in rare cases
  • allergic reaction*†
  • low levels of certain vitamins

If you develop serious side effects while taking Welchol, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Welchol. But it’s not clear whether this side effect occurred in studies.

Get answers to some frequently asked questions about Welchol’s side effects.

Does Welchol cause weight loss or weight gain?

In studies, some people who took Welchol for type 2 diabetes lost a small amount of weight. Other people in the studies experienced no change in weight or a small amount of weight gain. This varied depending on which other diabetes medications, if any, they took with Welchol.

In studies, weight gain was more likely when people used Welchol with diabetes drugs known to cause weight gain. These include insulins such as Tresiba (insulin degludec) and sulfonylureas such as Glucotrol XL (glipizide).

If you experience nausea or indigestion with Welchol, this could reduce your appetite. In some people, this may lead to weight loss. Also, Welchol is prescribed along with diet and exercise. In some cases, making changes to your diet and exercise routine could lead to weight loss.

If you have questions about changes in weight with Welchol or what to expect from your treatment, talk with your doctor.

Do side effects of Welchol vary between the 625-mg tablet and the liquid suspension?

No, side effects of Welchol aren’t known to vary between the 625-milligram (mg) tablet and the liquid suspension. No differences in side effects were reported in the drug’s studies.

If you have questions about your risk of side effects from Welchol, talk with your doctor or pharmacist.

Is memory loss a side effect of Welchol?

No, Welchol shouldn’t cause memory loss. This wasn’t a side effect reported in studies of the drug.

Welchol is sometimes taken along with a statin drug to treat high cholesterol. It’s unknown whether statins can cause memory loss. To learn more about statins and memory loss, see this article.

If you or a loved one notices that you’re experiencing memory loss during your treatment for high cholesterol, let your doctor know right away. They can try to determine the cause of your memory loss and discuss your treatment options.

Does Welchol cause hair loss?

No, Welchol doesn’t cause hair loss. This wasn’t reported in studies of the drug.

Low vitamin absorption is a possible side effect of Welchol. In some cases, this could contribute to hair thinning or loss. For details about the symptoms of vitamin deficiencies, see this article.

Welchol is sometimes taken along with a statin drug to treat high cholesterol. In rare cases, statins have caused hair loss. Other medications that lower cholesterol have rarely caused hair loss.

If you’re concerned about your cholesterol medications causing hair loss, talk with your doctor.

Welchol can be used to lower low-density lipoprotein (LDL) cholesterol in children ages 10–17 years who have a genetic (inherited) condition called heterozygous familial hypercholesterolemia.

In studies, most side effects in children taking Welchol were the same as those seen in adults. But children also experienced a few additional side effects, including:

To learn more about your child’s risk of side effects with Welchol, talk with their doctor.

Learn more about some of the side effects Welchol may cause in adults.

Nausea

Nausea can occur during Welchol treatment. In studies, this was more common than some of the drug’s other side effects. In most cases, nausea from Welchol is mild.

What might help

You can try a few remedies at home to help ease nausea:

  • drinking plenty of fluids to stay hydrated
  • eating bland foods such as crackers and broth
  • eating smaller, more frequent meals

Your doctor can give you more suggestions on how to manage nausea during your Welchol treatment.

Some over-the-counter medications (OTC), such as Pepto-Bismol (bismuth subsalicylate) or calcium carbonate, can also help to treat nausea. Before you try an OTC nausea medication, talk with your doctor. They can let you know about any OTC drugs that may interact with Welchol or your other medications.

If your nausea doesn’t go away after a few hours, or if you vomit several times from nausea, call your doctor. Your doctor can determine the cause of your symptoms and recommend an appropriate treatment.

Low blood sugar

Welchol can cause low blood sugar in some people. In studies of people taking Welchol for type 2 diabetes, low blood sugar was more common than some of the drug’s other side effects. But most people who used Welchol didn’t have low blood sugar.

Low blood sugar with Welchol is more likely in people who take other medications that lower blood sugar. These include sulfonylureas, insulin, and metformin.

Symptoms of low blood sugar include:

In rare cases, low blood sugar can be severe. Symptoms of severely low blood sugar can include seizures and loss of consciousness. In some cases, severely low blood sugar can lead to coma or may even be fatal. If you’re concerned about your risk of low blood sugar with Welchol, talk with your doctor.

What might help

If you have type 2 diabetes, your doctor or pharmacist will help you create an action plan for if your blood sugar gets too low. This usually involves a specific routine. For example, some people will take 15 grams of glucose or drink 4 ounces of juice or non-diet soda, wait 15 minutes, and check their blood sugar level.

Welchol is prescribed along with diet and exercise. Your doctor can suggest a diet and exercise plan to fit your needs and help manage your blood sugar.

If you have questions about your risk of low blood sugar while taking Welchol, talk with your doctor. But if your symptoms feel severe or life threatening, go to the closest emergency room or call 911.

Allergic reaction

Like most drugs, Welchol can cause an allergic reaction in some people. But in studies of the drug, this side effect occurred in only one person.

Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, usually in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest an OTC oral antihistamine, such as Benadryl (diphenhydramine), or a product you apply to your skin, such as hydrocortisone cream, to manage your symptoms.

If your doctor confirms you had a mild allergic reaction to Welchol, they’ll decide whether you should continue taking it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Welchol, they may have you switch to a different treatment.

Keeping track of side effects

During your Welchol treatment, consider keeping notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were taking when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how it affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help them learn more about how Welchol affects you. They can then use this information to adjust your treatment plan if needed.

Welchol may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before starting Welchol. The list below includes factors to consider.

Sensitivity to phenylalanine: Welchol oral suspension contains phenylalanine, a substance that makes it taste better. Some people with a rare medical condition called phenylketonuria can have a reaction to phenylalanine. If you have phenylketonuria, Welchol oral suspension may not be safe for you, but you may be able to take the tablet form. Talk with your doctor about whether Welchol is right for you.

High triglycerides: If you have a high level of triglycerides, this can lead to pancreatitis. Your doctor likely won’t prescribe Welchol for you if your triglycerides are above a certain level or if you’ve previously had pancreatitis because of high triglycerides. If you have high triglycerides, talk with your doctor to see whether Welchol is safe for you to take. If they decide to prescribe Welchol for you, they may monitor your triglyceride levels closely during your treatment through blood tests.

Allergic reaction: If you’ve had an allergic reaction to Welchol or any of its ingredients, your doctor will likely not prescribe Welchol. Ask them what other medications are better options for you.

Vitamin deficiencies: If your body doesn’t get enough of certain vitamins, including vitamins A, D, E, and K, Welchol may not be right for you. This is because Welchol can prevent your body from absorbing these vitamins when you eat. So if you already have a low amount of these vitamins, Welchol can make this deficiency worse. Your doctor can determine whether you may take Welchol.

Blockage in your intestines: If you have a medical condition that causes slow or difficult digestion, Welchol may not be right for you. This drug may raise your risk of a blockage in your intestines. If you’ve had issues with this type of blockage before, your doctor likely won’t prescribe Welchol for you. Your doctor can determine whether Welchol is safe for you to take.

Alcohol use and Welchol

It should be safe to drink alcohol while taking Welchol. But both Welchol and alcohol can cause nausea, so consuming alcohol during your treatment may make this side effect worse.

Also, both Welchol and excessive alcohol use can increase your triglyceride levels. This increases your risk of acute pancreatitis (swelling of the pancreas).

If you drink alcohol, talk with your doctor about the amount that may be safe to drink during your Welchol treatment.

Pregnancy and breastfeeding while taking Welchol

It’s not known whether Welchol is safe to use during pregnancy or while breastfeeding.

If you’re pregnant or breastfeeding, or planning to become pregnant or breastfeed, talk with your doctor about whether Welchol is right for you.

Like other medications, Welchol may cause mild or serious side effects. You can ask your doctor about ways to lower your risk of side effects or treat them if they occur. Here are a few questions to get you started:

  • Does the Welchol tablet cause fewer side effects than the oral suspension?
  • Does Welchol cause any long-term side effects?
  • What can I do to lower my risk of side effects from Welchol?
  • How do I know if I have high triglycerides?
  • Do any of my current medical conditions raise my risk of side effects from Welchol?

To learn more about Welchol, see these articles:

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Q:

Will my side effects from Welchol be worse if I also take a statin?

Anonymous

A:

It’s possible. Welchol is sometimes taken along with a statin drug to treat high cholesterol.

Some of Welchol’s side effects, such as muscle pain and nausea, can also be side effects of statins. Some people taking both drugs may have a higher risk of certain side effects. Or the side effects they experience may be worse.

If you have concerns about your risk of side effects during your Welchol treatment, talk with your doctor or pharmacist.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.
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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.