Gleevec (imatinib) is a brand-name oral tablet prescribed for some types of blood cancer in adults and some children. It’s also used in adults to treat some types of gastrointestinal cancer and skin cancer. As with other drugs, Gleevec can cause mild and serious side effects.

Gleevec can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days or weeks. But 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 Gleevec in clinical studies:

Mild side effects can occur when taking Gleevec. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Gleevec’s prescribing information.

Mild side effects that have been reported with Gleevec include:

These side effects may be temporary, lasting a few days or weeks. But 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 Gleevec and want to tell the FDA about it, visit MedWatch.

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

Gleevec may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Gleevec’s prescribing information.

If you develop serious side effects while taking Gleevec, 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 include:

  • Blood disorders, such as anemia (low levels of red blood cells), neutropenia (low levels of white blood cells), and thrombocytopenia (low platelet levels). Symptoms can include:
    • bleeding gums
    • blood in urine or stool
    • bruising easily
    • fatigue
    • fevers
    • frequent infections
    • fast heart rate
    • shortness of breath
  • Gastrointestinal (stomach or intestinal) problems, including perforations (tears). Symptoms can include:
    • fever
    • fast heart rate
    • nausea
    • severe abdominal pain
    • shortness of breath
    • vomiting
  • Heart problems, including heart failure. Symptoms can include:
    • abnormal heart rate or rhythm (such as feeling like your heart beat is too fast, too slow, or irregular)
    • chest pain
    • edema, also called fluid retention (excess fluid that can cause swelling of the feet, ankles, and legs)
    • shortness of breath
    • unexpected weight gain
  • Kidney damage. Symptoms can include:
    • confusion
    • edema
    • fatigue
    • high blood pressure
    • nausea
    • urinating less often than usual
  • Liver damage, including liver failure. Symptoms can include:
  • Severe edema in or around your heart, lungs, or abdomen. Symptoms can include:
    • chest pain
    • trouble breathing when you lie down
    • dry cough
    • shortness of breath
    • swollen abdomen
    • trouble taking deep breaths
    • unintentional, quick weight gain
  • Severe hemorrhage (bleeding that won’t stop), commonly in the intestines. Symptoms can include:
    • black, bloody, or tar-like stool
    • coughing up blood or black material
    • fatigue
    • nausea
    • abdominal cramps
  • Tumor lysis syndrome (release of harmful substances into your blood due to the death of cancer cells). Symptoms can include:
  • Eye side effects.*
  • Serious skin problems.*
  • Delayed growth in children.†
  • Allergic reaction.*

* For more information about this side effect, see “Side effect specifics” below.
† For more information on this side effect, see “Side effects in children” below.

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

Does stopping Gleevec cause withdrawal side effects?

It’s possible that suddenly stopping Gleevec could cause withdrawal side effects. (Withdrawal symptoms are effects that can occur when you stop taking a drug that your body has become dependent on.)

People taking Gleevac in the drug’s clinical studies did not report withdrawal symptoms. However, an older article reported that some people experienced bone pain and muscle pain after stopping Gleevec. These side effects went away within 3 months to about 1 year.

Do not stop taking Gleevec without speaking with your doctor first. If you’re considering stopping Gleevec, talk with your doctor about treatments you could use in case you have any symptoms after stopping the drug. These may include over-the-counter painkillers such as ibuprofen (Motrin, Advil) or acetaminophen (Tylenol).

How long do Gleevec’s side effects last? Are any side effects long term?

Most of Gleevec’s side effects last for a short time. Often, they’ll go away on their own after a few days or weeks.

Gleevec can also cause long-term side effects, including heart failure and certain blood disorders. (See “Serious side effects of Gleevec” above for details.) Your risk for serious side effects, including long-term side effects, decreases as you continue to take the drug.

If you’re concerned about long-term side effects from Gleevec, talk with your doctor. They may suggest ways to reduce your risk for certain side effects. They’ll also monitor you for symptoms of long-term side effects while you’re taking Gleevec.

What are the side effects of Gleevec 400 mg?

Clinical studies of Gleevec included people who took a 400-milligram (mg) dose of the drug. Some common side effects reported in these studies include:

For a full list of side effects Gleevec may cause, see the “Mild side effects” and “Serious side effects” sections above.

What side effects does Gleevec cause when taken to treat GIST?

Gleevec is approved to treat gastrointestinal stromal tumors (GISTs). This is a type of cancer that affects your stomach or intestines. Some common side effects reported by people who took Gleevec to treat GIST in clinical studies include:

  • edema
  • fatigue
  • nausea and vomiting
  • abdominal cramps
  • diarrhea

See “Mild side effects” and “Serious side effects” above for more information about side effects of Gleevec. You can also refer to Gleevec’s prescribing information.

What are the side effects of generic Gleevec?

The generic form of Gleevec is called imatinib. Side effects of these drugs are similar. This is because a generic medication is an exact copy of the active drug in a brand-name medication.

Your doctor or pharmacist can provide more information about how Gleevec compares with imatinib.

Learn more about some of the side effects that Gleevec may cause.

Hair loss

Gleevec may cause hair loss. Hair loss caused by cancer treatments such as Gleevec is usually temporary. This means that any hair you lose will likely regrow after you stop taking Gleevec.

What you can do

If you’re concerned about hair loss while taking Gleevec, talk with your doctor. They may recommend ways to manage or reduce this side effect.

Eye side effects

Eye-related side effects were reported by some people taking Gleevec in clinical studies.

The most common eye side effects caused by Gleevec are blurry vision and swelling. Some less common eye side effects include:

What you can do

You should avoid driving or operating machinery until you know how Gleevec will affect you. Eye side effects (and non-eye-related side effects such as dizziness) can make it dangerous to drive and do similar activities.

Talk with your doctor if you have symptoms of eye side effects while taking Gleevec.

If you have swelling around your eye, your doctor may prescribe a diuretic (also called a water pill). Diuretics help your body get rid of excess fluid, which can reduce swelling.

If you have blurry vision or other eye problems, your doctor may recommend you see an eye doctor or specialist. They may also decrease your Gleevec dosage. Or they may recommend that you stop taking Gleevec and try a different medication.

Skin problems, such as a rash

Gleevec can cause mild or serious skin problems. A mild rash was one of the more common side effects reported by people taking Gleevec in clinical studies. Other mild skin problems may include:

Higher doses of Gleevec may be more likely to cause skin problems.

Although rare, Gleevec can also cause serious skin problems, such as:

What you can do

Contact your doctor if you have symptoms of mild skin side effects, such as a rash, while taking Gleevec. They may recommend ways to relieve your symptoms.

If you think you may be experiencing a serious skin reaction, contact your doctor right away. Although rare, some serious skin reactions can be life threatening.

Allergic reaction

As with most drugs, Gleevec can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • rash
  • itching
  • flushing (temporary warmth, redness, or deepening of skin color)
  • 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 Gleevec. But if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Children who took Gleevec in clinical studies had side effects that were very similar to those in adults. In these studies:

  • the most common mild side effects in children were nausea and vomiting
  • neutropenia (low levels of white blood cells) and thrombocytopenia (low platelet levels) were the most common serious side effects in children
  • fewer children experienced muscle pain or bone pain than adults
  • edema, also called fluid retention (excess fluid that can cause swelling), wasn’t reported in children

Gleevec can also cause delayed growth in children and adolescents younger than 18 years old. Delayed growth refers to not growing at a typical rate. This may cause your child to be smaller in size than other children their age.

It’s not known whether this may result in long-term effects on growth. Your child’s doctor will closely monitor your child’s development and how quickly they grow while taking Gleevec.

Your child’s doctor can answer any questions about Gleevec and its side effects in children.

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

Being age 65 years or older: If you’re age 65 or older, you may be at higher risk for certain side effects caused by Gleevec. This includes fluid retention (excess fluid that causes swelling in your feet, ankles, or legs). Your doctor may monitor you for this side effect more closely if you’re prescribed Gleevec and you’re age 65 or older.

Heart or kidney problems, including hypereosinophilic syndrome (HES): Gleevec may cause problems with your heart or kidneys, including heart failure or kidney failure. If you already have heart or kidney problems, including HES, you may be at higher risk for these side effects. Your doctor can help determine if Gleevec is safe for you to take.

Use of levothyroxine (Synthroid) after thyroidectomy: A thyroidectomy is surgery to remove your thyroid gland. If you’re taking levothyroxine or Synthroid to increase your thyroid hormone levels, your doctor may monitor you more closely than usual while you take Gleevec. This is because Gleevec may cause low thyroid hormone levels. Your doctor can provide more information about this.

Liver problems: Taking Gleevec can cause liver problems, including liver failure and liver damage that’s severe enough to require a transplant. If you have existing liver problems, you may be at higher risk for these side effects. Your doctor can give you more information and help determine whether treatment with Gleevec is safe for you.

Allergic reaction: You should not take Gleevec if you’ve ever had an allergic reaction to Gleevec or any of its ingredients. Talk with your doctor about other treatments that might be better choices for you.

Alcohol use with Gleevec

Alcohol isn’t known to interact with Gleevec. But drinking alcohol while taking Gleevec could increase your risk for mild side effects. These include nausea, diarrhea, headache, and fatigue. This is because both alcohol and Gleevec can cause these side effects.

Alcohol use with Gleevec may also increase your risk of liver damage. This is a possible serious side effect of Gleevec. Alcohol can also cause liver damage, so combining the two may increase your risk.

If you drink alcohol and you’re taking Gleevec, ask your doctor how much alcohol, if any, is safe to drink.

Pregnancy and breastfeeding while taking Gleevec

You should avoid taking Gleevec while pregnant. There have been reports of pregnancy loss and harm to the fetus when people took Gleevec during pregnancy. If you can become pregnant, talk with your doctor about your birth control options while taking Gleevec. You’ll need to use birth control while taking Gleevec and for at least 14 days after your last dose.

You should avoid breastfeeding while taking Gleevec and for at least 1 month after your last dose. The drug could cause serious side effects in a breastfed child. Your doctor can recommend safe feeding options for your child.

If you’d like to learn more about Gleevec, talk with your doctor or pharmacist. They can help answer any questions you have about managing side effects from taking the drug. And make sure to talk with your doctor if you have any symptoms of serious side effects of Gleevec.

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

  • More information on Gleevec. For details on other aspects of Gleevec, refer to this article.
  • Dosage. For information about Gleevec’s dosage, you can see this article.
  • How it works. To learn about how Gleevec works, refer to this article.
  • A look at cancer. For details on cancer, see our cancer hub as well as this list of related articles.

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.