Venclexta (venetoclax) is a brand-name oral tablet that’s prescribed for certain types of cancer in adults. As with other drugs, Venclexta can cause side effects, such as nausea, fatigue, or dizziness.

Venclexta can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Venclexta in clinical trials. These side effects can vary depending on which condition the drug is being used to treat.

More common side effects in people who took Venclexta for chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) included:

More common side effects in people who took Venclexta for acute myeloid leukemia (AML) included:

Mild side effects can occur with Venclexta. They can vary depending on which condition the drug is being used to treat. This list doesn’t include all possible mild side effects of Venclexta. For more information, you can refer to Venclexta’s prescribing information.

Mild side effects in people who took Venclexta for CLL or SLL in clinical trials included:

  • nausea
  • diarrhea
  • cough
  • fatigue
  • respiratory infections, such as the common cold
  • muscle or bone pain*
  • swelling, especially of the arms or legs*

Mild side effects in people taking Venclexta for AML in clinical trials included:

  • nausea
  • bleeding
  • dizziness
  • diarrhea or constipation
  • fatigue
  • vomiting
  • fever
  • difficulty breathing
  • skin rash
  • abdominal pain
  • cough
  • mouth pain
  • muscle or bone pain*
  • swelling, especially of the arms or legs*

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Venclexta and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Venclexta may cause serious side effects. These are less common than mild side effects. The list below applies to both CLL and SLL. However, the list may not include all possible serious side effects of the drug. For more information, you can refer to Venclexta’s prescribing information.

If you develop serious side effects while taking Venclexta, 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.

Serious side effects that have been reported and their symptoms include:

  • Low blood pressure. Symptoms can include:
    • dizziness
    • blurry vision
    • nausea
    • difficulty concentrating
  • Low levels of certain blood cells. Symptoms can include:
    • difficulty breathing
    • more frequent infections
    • bruising more easily than usual
    • prolonged bleeding from cuts or wounds
  • Tumor lysis syndrome (a condition in which cancer cells release harmful chemicals into the blood). Symptoms can include:
  • Infection.*
  • Allergic reaction.*†

* To learn more, see the “Side effect specifics” section below.
† An allergic reaction is possible after taking Venclexta. However, this side effect wasn’t reported in clinical trials.

Venclexta may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Are there any long-term side effects of Venclexta?

It’s possible to develop long-term side effects from taking Venclexta, but this is uncommon. Most side effects that people taking Venclexta experienced in clinical trials were short term. These short-term side effects may go away during your treatment or after you stop taking the drug.

An example of a serious long-term side effect is kidney damage due to tumor lysis syndrome. (With this syndrome, cancer cells release harmful chemicals into the blood.)

Some other side effects may continue after you stop Venclexta treatment. For example, muscle or bone pain can last even if you no longer take the medication.

If you’re concerned about long-term side effects from Venclexta, talk with your doctor. They may be able to recommend ways to help prevent these side effects from occurring.

Does Venclexta cause hair loss?

You should not experience hair loss with Venclexta. Hair loss was not a side effect seen in clinical trials of people taking Venclexta.

Other medications that may be used to treat cancer may cause hair loss to occur. These can include chemotherapy.

If you’re concerned about losing your hair, talk with your doctor. They can help determine if any of your cancer drugs may cause hair loss.

Learn more about some of the side effects that Venclexta may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Venclexta.

Infection

Venclexta may increase the risk of infection. This is because the drug can affect the levels of white blood cells, and these cells help your body fight infection.

Infections can occur in people taking Venclexta for CLL, SLL, or AML.

In some cases, infections may be mild, such as the common cold. Venclexta can also cause more serious infections to occur, such as pneumonia. In addition, the drug can cause sepsis, which is a dangerous reaction to an infection.

Symptoms of an infection may include:

What you can do

If you develop any symptoms of an infection while taking Venclexta, talk with your doctor right away. In many cases, infections are mild. Your doctor may recommend that you take an antibiotic or other medication to treat the infection.

If you have a high fever or trouble breathing, your doctor may advise you to go to the hospital or seek other emergency care. A temperature above 103.1°F (39.5°C) is considered to be a high fever.

There may be other symptoms of infection you should watch for. Your doctor will likely discuss these with you before you start taking Venclexta.

Muscle or bone pain

Muscle or bone pain may occur with Venclexta. These were common side effects that people taking Venclexta reported in clinical trials. Muscle or bone pain occurred in people taking the drug for CLL, SLL, or AML.

What you can do

If you experience muscle or bone pain with Venclexta, talk with your doctor. They may suggest an over-the-counter pain reliever, such as Tylenol (acetaminophen) or Advil (ibuprofen). Your doctor may also recommend exercise. If your pain is severe, they may lower your dosage of Venclexta or pause your treatment.

Swelling, especially of the arms or legs

Swelling is a possible side effect of Venclexta. Swelling most often occurs in the arms, legs, feet, or hands. This was a common side effect that occurred in people taking Venclexta for CLL, SLL, or AML in clinical trials.

What you can do

If you notice swelling in your arms or legs while you take Venclexta, talk with your doctor about how to treat it. In some cases, they may recommend that you elevate your arm or leg to try to decrease the swelling. If your swelling is severe, your doctor may recommend a prescription medication, such as a diuretic, to ease the swelling.

Allergic reaction

As with most drugs, Venclexta can cause an allergic reaction in some people. However, this side effect wasn’t reported in clinical trials.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Venclexta. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Venclexta. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Kidney problems: Tell your doctor about any kidney problems you have before you start taking Venclexta. Kidney problems may increase your risk of certain side effects, such as tumor lysis syndrome. Your doctor may monitor your blood levels more often than usual during your Venclexta treatment.

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

Liver problems: If you have liver problems, talk with your doctor before you start taking Venclexta. If your liver isn’t working as well as it should, the drug can build up in your body and increase your risk of side effects. For this reason, if you have certain liver problems, your doctor may recommend that you take a lower dosage of Venclexta than usual. This is meant to help prevent side effects from occurring.

Electrolyte problems: If you have problems with your blood electrolyte levels, you may be at an increased risk of side effects from Venclexta. The drug may also worsen your condition. This is because Venclexta may cause tumor lysis syndrome, which may trigger atypical electrolyte levels.

Problems with electrolyte levels include trouble regulating your potassium, calcium, or phosphorus levels.

Talk with your doctor about any electrolyte conditions you may have. They may recommend treatment to return your electrolyte levels to usual before you start taking Venclexta. Your doctor may also monitor the levels more often than usual throughout your treatment with Venclexta.

High uric acid level or gout: If you have or had a high uric acid level or gout, tell your doctor before you start taking Venclexta. This medication may cause tumor lysis syndrome to occur, which can increase uric acid levels. If your uric acid level is already high, Venclexta may worsen your condition. Your doctor may recommend medication to lower the level. They may also monitor your uric acid level more often than usual throughout your Venclexta treatment.

Alcohol use with Venclexta

There are no known interactions between Venclexta and alcohol.

However, drinking alcohol may worsen some of the side effects of Venclexta. For example, both Venclexta and alcohol can cause nausea, vomiting, and dizziness. You may be at an increased risk of these side effects if you drink alcohol while taking the medication.

If you drink alcohol, talk with your doctor about how much is safe for you to drink while you take Venclexta.

Pregnancy and breastfeeding while taking Venclexta

Here’s some information about pregnancy, breastfeeding, and Venclexta.

Pregnancy: Venclexta may cause harm to a developing fetus if the drug is taken during pregnancy. At this time, clinical trials have not studied the safety of the drug in pregnant people.

In animal trials,* pregnant animals given Venclexta experienced increased rates of pregnancy loss.

Due to this risk, if you can become pregnant, your doctor will order a pregnancy test before you start taking Venclexta. This is to confirm that you’re not pregnant. They’ll also recommend that you use an effective form of birth control while taking Venclexta and for at least 30 days after stopping treatment.

If you’re a male† taking Venclexta and your sexual partner can become pregnant, talk with your doctor about birth control. The manufacturer of Venclexta hasn’t provided guidance about birth control in males taking the drug.

Breastfeeding: Due to the risk of a child who’s breastfed being exposed to Venclexta in breast milk, breastfeeding while taking Venclexta is not recommended. You should also not breastfeed for at least 1 week after stopping Venclexta treatment.

It’s not known whether Venclexta passes into human breast milk or what effects the drug may have on a child who is breastfed. In animal trials,* Venclexta did pass into breast milk.

Talking with your doctor. If you’re pregnant or planning a pregnancy, talk with your doctor. You should also talk with them if you’re breastfeeding or planning to. They can advise you on treatment options for your cancer and healthy ways to feed your child.

* Animal trials do not always predict what may happen in humans.
† Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Although you may experience side effects from taking Venclexta, most are mild. Serious side effects are possible as well. If you develop serious side effects during your treatment, be sure to talk with your doctor.

If you’d like to learn more about Venclexta, talk with your doctor or pharmacist. They can help answer any questions you have about side effects of taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today 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.