Imatinib

Say it: ih-MA-tih-nib · Brand names: Gleevec, Imkeldi

Imatinib is a targeted pill that blocks the abnormal protein that drives some leukemias and some other cancers.

What it is

In chronic myeloid leukemia, two genes join to make an abnormal protein called BCR-ABL. It tells blood cells to grow out of control. Imatinib blocks BCR-ABL and a few related proteins, like KIT in stomach tumors called GIST.

Often used for

• chronic myeloid leukemia (CML)
• acute lymphoblastic leukemia with the Philadelphia chromosome
• gastrointestinal stromal tumors (GIST), including after surgery
• a skin tumor called dermatofibrosarcoma protuberans
• some rare blood and bone marrow conditions

How you get it

It is a pill you take by mouth once or twice a day with a meal and a large glass of water. A liquid form is also available. Many people with leukemia take it for years. Your schedule may be different.

Common side effects and what helps

• Puffy eyes or swelling in the legs. Weigh yourself often and limit salt.
• Nausea. Taking it with food and a full glass of water helps.
• Muscle cramps or bone aches. Stretch gently and drink fluids.
• Diarrhea. Drink plenty of fluids.
• Rash. Use gentle soap and moisturizer.
• Feeling tired. Rest when you need to and take short walks when you can.
• Low blood counts, found on blood tests. Your team will check them.

Call your care team right away if you have

• Fast weight gain, or swelling with shortness of breath
• A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, chills, or other signs of infection
• Bleeding that will not stop, black or bloody stools, or coughing up blood
• Yellow skin or eyes, dark urine, or pain on the right side of your belly
• Skin that blisters or peels
• Bad belly pain

Before you start, tell your team

• If you have heart, liver, or kidney problems
• If you take thyroid hormone, such as levothyroxine
• If you are pregnant, may become pregnant, or are breastfeeding
• All the medicines, vitamins, and herbal products you take, since some can change how this medicine works

Good to know

• You will have blood tests to check your blood counts and liver, more often at first.
• It can cause fluid to build up. Your team will watch your weight.
• In children, it can slow growth, so growth is watched closely.
• This medicine can harm an unborn baby. Ask your team about birth control during treatment and for a while after.

At home

• Take it with a meal and a large glass of water.
• If you cannot swallow the pills, ask your team how to mix them in water or apple juice.
• Avoid touching crushed pills with bare skin. Wash your hands after handling them.
• If you miss a dose or throw up after a dose, ask your team what to do. Do not take an extra dose on your own.
• Store the pills at room temperature in their original container, away from children and pets.
• Do not eat grapefruit or drink grapefruit juice, since it can raise the amount of medicine in your blood.

Questions to ask

• How long will I take this medicine?
• How often will I have blood tests to check how well it is working?
• Are any of my other medicines, foods, or supplements a problem with this medicine?
• What should I do if I miss a dose?
• Which side effects should I call you about right away, and which can wait?

Side effect guides

• Fatigue (tiredness)
• Nausea and vomiting
• Diarrhea
• Skin rash (including EGFR-inhibitor rash)

Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.