Rezurock (belumosudil) is a prescription drug used to treat chronic (long-term) graft-versus-host disease. Rezurock can cause side effects that range from mild to serious. Examples include diarrhea and changes in blood pressure.

Rezurock is used in adults and certain children to treat chronic (long-term) graft-versus-host disease (GVHD). Doctors usually prescribe the drug after at least two other GVHD treatments haven’t worked.

The active ingredient in Rezurock is belumosudil. (An active ingredient is what makes a drug work.) The drug comes as an oral tablet.

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

Some people may experience mild to serious side effects during Rezurock treatment. Examples of the drug’s commonly reported side effects include:

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

Mild side effects have been reported with Rezurock. These include:

In most cases, these side effects should be temporary. And some may be easily managed. If you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop taking Rezurock unless your doctor recommends it.

Rezurock may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after taking Rezurock, but this side effect wasn’t reported in studies.

Serious side effects have been reported with Rezurock. These include:

If you develop serious side effects while taking Rezurock, 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 Rezurock, but this side effect wasn’t reported in studies.

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

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

How do side effects of Rezurock compare with those of Jakafi?

Many of Rezurock’s side effects are similar to those of Jakafi (ruxolitinib). But Jakafi may cause different side effects as well.

For example, both Rezurock and Jakafi may cause:

  • shortness of breath
  • mild and serious infections
  • diarrhea*

But Jakafi may also increase the risk of certain cancers and heart and blood vessel problems, such as stroke and heart attack. These side effects weren’t reported with Rezurock.

For lists of possible side effects of Rezurock, see the sections above. To learn more about Jakafi’s side effects, see this article. You can also talk with your pharmacist or doctor.

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

Does Rezurock cause long-term side effects?

It’s rare but possible. Long-term side effects include those that may start at any time you’re taking a drug, even if you’ve taken it for a long time. It also includes side effects that may not go away, even after you stop taking the drug.

Below are examples of side effects that may have long-term effects and were reported in Rezurock’s studies:

Talk with your doctor to learn more about possible side effects of Rezurock and how long they may last.

Learn more about some of the side effects Rezurock may cause.

Diarrhea

Diarrhea was a common side effect reported in studies of Rezurock. Diarrhea may cause symptoms such as:

  • abdominal pain, cramping, or bloating
  • loose, watery stool
  • frequent urges to have a bowel movement

What might help

If you have diarrhea during Rezurock treatment, talk with your doctor. They can recommend over-the-counter options, such as Pepto-Bismol (bismuth subsalicylate), to help relieve your symptoms.

It’s also recommended that you take your Rezurock dosage with food. Doing so can help prevent or ease digestive side effects, including diarrhea.

Changes in blood pressure

Taking Rezurock may lead to changes in blood pressure. High blood pressure was a common side effect reported in studies of Rezurock, while low blood pressure was less common.

High blood pressure may not cause symptoms unless it’s severely high. Symptoms of severely high blood pressure can include:

  • dizziness
  • headache
  • flushing (temporary warmth, redness, or deepening of skin color)

Low blood pressure may cause symptoms such as:

What might help

During your Rezurock treatment, your doctor may advise you to check your blood pressure at home. They’ll tell you how often to check it and can recommend a home monitor for you.

If you have changes in blood pressure during Rezurock treatment, talk with your doctor. They can tell you whether it’s safe to keep taking the drug. They can also recommend ways to help manage your blood pressure.

Allergic reaction

Like most drugs, Rezurock can cause an allergic reaction in some people. But this side effect wasn’t reported in studies. Symptoms can be mild to serious and can include:

  • skin rash
  • itchiness
  • flushing
  • 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 a treatment to manage your symptoms. Examples include:

  • an oral antihistamine, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Rezurock, they’ll decide if 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’ve had a serious allergic reaction to Rezurock, they may have you switch to a different treatment.

Keeping track of side effects

During your Rezurock treatment, consider taking 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 a new drug or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the 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 your symptoms 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 Rezurock affects you. They can then use this information to adjust your treatment plan if needed.

Below is important information you should consider before taking Rezurock.

Warnings

Rezurock can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Rezurock is a good treatment option for you.

Talk with your doctor about your health history before starting this medication. Be sure to tell them if any of the following factors apply to you:

Alcohol and Rezurock

There are no known interactions between alcohol and Rezurock. If you have questions about consuming alcohol while taking this medication, talk with your doctor or pharmacist.

Pregnancy and breastfeeding with Rezurock

Before starting Rezurock treatment, it’s important to talk with your doctor if you’re pregnant, breastfeeding, or planning to be either.

Pregnancy

Rezurock is not safe to take during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor about your treatment options.

If you’re able to become pregnant, your doctor may recommend using a form of birth control during your Rezurock treatment. You may also need to continue taking birth control for 1 week after your Rezurock treatment ends.

Breastfeeding

Rezurock is not safe to take while breastfeeding. Your doctor will likely advise you to avoid breastfeeding during your Rezurock treatment and for at least 1 week after treatment ends. If you’re breastfeeding or planning to do so, talk with your doctor about your options.

Like most drugs, Rezurock can cause a number of side effects that range from mild to serious. But most are temporary and go away after a few days to weeks. If you have questions about side effects that Rezurock can cause, talk with your doctor. Examples to help get you started include:

  • Does my risk of side effects depend on the Rezurock dosage I take?
  • Are there any side effects of Rezurock I should tell you about right away?
  • Do I have any health factors that increase my risk of side effects from Rezurock?

To learn more about Rezurock, see these articles:

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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.