Venclexta (venetoclax) can cause side effects that range from mild to serious. More common side effects include nausea, diarrhea, and anemia. If side effects from Venclexta become difficult to tolerate, talk with your doctor about coping tips or other treatment options.

Venclexta is used in adults to treat:

Keep reading to learn about the common, mild, and serious side effects Venclexta can cause. To learn more about Venclexta, including its uses, dosage, and cost, read this Venclexta overview.

The following lists contain a few of the more common side effects reported by people who took Venclexta in studies. These side effects can vary depending on the condition being treated.

More common side effects in people taking Venclexta for CLL or SLL include:

In people taking Venclexta for AML, more common side effects include:

  • low blood cell levels
  • nausea
  • diarrhea or constipation
  • fever
  • edema

For more information about some of these common Venclexta side effects, see the “Side effect specifics” section.

Taking Venclexta may cause mild side effects in some people. These side effects can vary depending on the condition you’re using the drug to treat. Examples of mild side effects that have been reported with Venclexta include:

In most cases, these side effects should be temporary. And some may be easily managed, too. But if you have any symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop using Venclexta unless your doctor recommends it.

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

For more information about some of these mild Venclexta side effects, see the “Side effect specifics” section.

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Venclexta may cause serious side effects. The following 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:

For more information about some of these serious Venclexta side effects, see the “Side effect specifics” section.

Allergic reaction

For some people, Venclexta can cause an allergic reaction.

But it’s not clear whether this side effect occurred in the drug’s studies.

In general, symptoms of an allergic reaction can be mild or serious, and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically 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 and can determine whether you should keep taking Venclexta.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty 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 Venclexta, they may have you switch to a different treatment.

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

Edema

Edema (fluid buildup) is a common side effect of Venclexta. Fluid may collect in various areas of the body and cause swelling. Fluid buildup from Venclexta most commonly causes swelling of the legs, arms, feet, and hands.

In studies of people who took Venclexta for AML, fluid buildup caused swelling in several parts of the body. In some people, fluid buildup or swelling was reported in the legs, arms, hands, feet, eyelids, and the area around the eyes, face, or penis.

Symptoms of fluid buildup may include:

  • swelling and puffiness
  • stiffness or pain
  • pitting of the skin
  • bruising or discoloration of the skin
  • difficulty putting on socks or shoes
  • weight changes

What might help

Treatment of edema depends on how severe the swelling is and what areas of your body are affected.

You may be able to ease swelling by placing a cold compress on the affected areas for a few minutes at a time. When possible, try to elevate the swollen area above heart level. For example, prop your legs up on pillows while you’re lying down.

Limiting sodium in your diet can help to ease fluid buildup. Being physically active and exercising also helps.

If your symptoms of this side effect become bothersome or severe, tell your doctor. They may suggest treatments, such as diuretics, to relieve this side effect, especially if you have certain health conditions.

Low blood cell levels

Taking Venclexta can lower the levels of certain cells in your blood. These include white blood cells, red blood cells, and platelets.

In studies, low blood cell levels commonly occurred in people taking Venclexta. The symptoms of this side effect depend on which types of blood cells have low levels.

Neutropenia (low levels of neutrophils, a type of white blood cell) is common while taking Venclexta. This increases your risk of infections because white blood cells fight off pathogens (germs) that cause infections. General symptoms of an infection can include fever, chills, body aches, and cough. If you develop infection symptoms while taking Venclexta, tell your doctor right away.

Thrombocytopenia (low platelet levels) is also a common side effect of Venclexta. If you don’t have enough platelets in your body, your blood won’t be able to clot (stop bleeding) after an injury. Symptoms can include bruising or bleeding easily, nosebleeds, coughing up blood, and blood in your urine, stool, or vomit.

Anemia (low red blood cell levels) can also occur while taking Venclexta. Red blood cells carry oxygen throughout your body. A typical symptom of anemia is fatigue.

What might help

Blood cell levels (also called blood cell counts) are measured using a blood test called a complete blood count (CBC). Your doctor will likely test your CBC regularly while you’re taking Venclexta.

If you develop symptoms of low blood cell levels, you should let your doctor know right away. Don’t wait to see if your symptoms go away on their own.

If your doctor confirms that your blood cell levels are low, they may have you pause or stop taking Venclexta. They may also prescribe certain medications or supplements to help treat or prevent low blood cell levels.

If you have questions about your risk of low blood cell levels, talk with your doctor or pharmacist.

Nausea

Nausea was one of the most common side effects reported in studies of people taking Venclexta. It’s also a common side effect of many types of medications used to treat cancer.

Nausea can cause vomiting and lead to dehydration.

What might help

It’s important to always take Venclexta with plenty of water. Continue to drink water throughout each day to keep your body hydrated.

If you develop nausea that becomes severe or doesn’t go away, tell your doctor. If you’re dehydrated due to vomiting, they may suggest medical care. This might include giving you fluids intravenously (through a vein). They may also prescribe an anti-nausea medication, such as Zofran (ondansetron).

Before taking Venclexta, discuss your health history with your doctor.

Venclexta may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

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.