8 Imatinib (Gleevec) Side Effects and How to Manage Them

Imatinib (Gleevec) is a prescription medication that treats various forms of blood cancer, gut-related cancer, and skin cancer. It comes as an oral tablet that you should take with food and a full glass of water.

Imatinib works by reducing the growth of cancer cells in your body. However, as with any medication, it may cause side effects. Some side effects are common and mild, while others are more serious. A combination of lifestyle and dietary changes, imatinib dosage adjustments, and supportive medications can all help combat side effects you may experience.

Imatinib side effects at a glance

Common imatinib side effects include:

• Fluid buildup

• Increased risk of infection

• Nausea

• Muscle cramps

• Muscle pain

• Diarrhea

• Rash

• Fatigue

• Headache

• Joint pain

• Stomach pain

• Cold symptoms

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Rare but serious imatinib side effects may include:

• Severe infection

• Liver problems

• Kidney issues

• Stomach or brain bleeds

• Low white blood cell, red blood cell, and platelet counts

• Rapid breakdown of cancer cells (tumor lysis syndrome)

• Heart problems

• Severe skin reactions, including Stevens-Johnson syndrome

Here, we’ll review eight notable imatinib side effects and how to manage them.

1. Fluid buildup

Fluid buildup (edema) happens when your body holds onto too much water and other fluids. Possible symptoms include swelling in your arms, legs, or around the eyes. This can also include puffiness around your ankles or hands. In rare cases, you may have buildup that affects your lungs, which can make it hard to catch your breath.

Fluid buildup is imatinib’s most common side effect overall. The risk of experiencing it is greater with larger imatinib doses and if you’re older than 65. Thankfully, you can take a few proactive measures to prevent substantial fluid buildup. 

For starters, consider reducing your salt intake. This is because high-salt foods and drinks can prompt your body to hold more fluid. Mild physical activity, such as walking or stretching, can also help. It’s important to weigh yourself on a regular basis, too. Large, unexpected weight changes are a possible sign of significant fluid buildup.

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Your oncologist will likely keep an eye on your body weight. They may prescribe you diuretics, or "water pills," to help your body remove excess fluid when needed. In other cases, they may need to adjust your imatinib dose if you have severe fluid buildup. The good news is that severe fluid buildup is rare.

2. Nausea

You may feel nauseated while taking imatinib. There are a few steps you can take on your own to feel better. 

For example, always take imatinib with food and a large glass of water. This helps reduce nausea and other gut-related side effects. Eating small, frequent meals throughout the day may also lessen nausea (in lieu of a few larger ones). Avoiding greasy, fried, or overly spicy foods can also reduce nausea. 

Speak to your oncologist if nausea becomes hard to handle. They may want to prescribe an anti-nausea medication.

Good to know: It’s best to speak to your oncologist before taking ginger supplements or consuming large amounts of ginger tea for nausea. This is because large quantities of ginger can increase your risk of stomach bleeds.

3. Diarrhea

Diarrhea is another common imatinib side effect. This may feel like a mild and self-resolving issue, but it’s important to stay on top of it. Diarrhea can lead to dehydration and other unwanted outcomes if it persists.

Eating a plain diet, such as the bananas, rice, applesauce, and toast (BRAT) diet, can help manage diarrhea symptoms in the short term. These foods are mild, easy to digest, and can reduce worsening digestive problems. However, it’s not a good idea to stick with the BRAT diet over time — it doesn’t have a lot of nutrients.

Staying hydrated is also important. Ask your oncologist about how much water or electrolyte-rich drinks you should consume.

Tell your oncologist if your diarrhea is bothering you. Also let them know if you experience diarrhea that lasts longer than 24 hours, notice blood in your stool, or develop a fever. They may need to adjust your imatinib dose to help your digestive system recover. They can also recommend an anti-diarrheal medication.

4. Muscle cramps

Imatinib may occasionally cause muscle cramps. You may feel cramps in your legs, arms, or hands that feel like sudden, uncomfortable contractions. Muscle cramps usually aren’t dangerous, but they can disrupt your day if you have them frequently.

It’s helpful to stay hydrated and ensure you’re consuming enough minerals in your diet, such as magnesium, calcium, and potassium. Low levels of these minerals can increase your risk of muscle cramps.

Muscle cramps can be hard to handle on your own though, so always feel empowered to contact your oncologist if you’re experiencing them. They can suggest exercises and stretches, among other tips, that can help lessen your symptoms.

5. Skin rashes

Skin rashes are another possible imatinib side effect. They may look like red, itchy patches or tiny, red flat spots. Most people only have mild skin symptoms, but more severe rashes can happen in rare cases. 

Rashes may be uncomfortable, but you can manage them in most cases. Avoiding harsh soaps and skincare products can help reduce irritation. Gentle, loose clothing can lessen friction and minimize skin irritation.

Contact your oncologist if your skin rash worsens, you develop blisters, or your rash spreads. They may want to adjust your imatinib dose or prescribe a topical corticosteroid. They can also take a look at your skin to make sure nothing severe is underway.

6. Low blood cell counts

Imatinib may lower your blood cell counts, including your white blood cells, red blood cells, and platelets. 

It’s possible that you’re taking imatinib to treat a cancer that’s causing high levels of white blood cells. But low white blood cell counts can also be harmful; a deficiency increases your risk of infection. Low red blood cell counts (anemia) can cause fatigue and weakness. Low platelets can increase your risk of bruising and bleeding.

Your oncologist will likely monitor your blood cell counts before you start imatinib and routinely while you’re taking it. They may adjust your imatinib dose and/or prescribe supportive medications to boost your blood cell counts.

7. Liver or kidney problems

Liver and kidney issues are possible with several cancer medications. They may be related to imatinib or another medication you may be taking.

Many people don’t have any visible symptoms when their liver isn’t working well. But possible symptoms of liver dysfunction include jaundice (yellowing of the skin or eyes), dark urine, and upper stomach pain. Severe liver toxicity is rare while taking imatinib, but it’s been reported in some cases.

Symptoms that may indicate kidney issues include sudden leg swelling or difficulty producing urine. Your kidneys’ job is to remove waste products from your body in your urine. Kidneys that aren’t producing urine can be a sign of an issue. However, overly frequent urination may be an issue too.

It’s hard to prevent kidney and liver problems on your own. Your oncologist should review your lab work routinely to monitor your liver and kidney health. Depending on what these tests show, they can stop or adjust your imatinib prescription.

8. Heart problems

Heart problems are rare with imatinib. But they can be serious when they do happen. Heart failure and abnormal left heart valve function have been reported in rare cases.

Keep an eye out for possible symptoms of cardiac dysfunction — especially if you have a history of heart problems. Symptoms to watch for include chest pain, feeling like you can’t catch your breath, and lower leg or ankle swelling. Seek medical care right away if you experience symptoms like these.

Your oncologist may refer you out to a cardiologist if they suspect heart problems. From there, a cardiologist may conduct additional tests to evaluate your heart health.

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Written by:

Mandeep Sohal, PharmD

Mandeep Sohal, PharmD, has more than 7 years of experience in the pharmaceutical industry and is licensed in California. In his career, he’s had experience with specialty pharmacy, community pharmacy, pharmacy benefit management, and pharmaceutical manufacturers.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Vanessa Carranza, PharmD

Vanessa Carranza, PharmD, is a pharmacist who has dedicated her career to the advancement of medical education for healthcare providers, patients, and caregivers, most notably in the oncology space.

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