Cytarabine is a chemotherapy medicine used most often for leukemia. You may hear it called an antimetabolite or Ara-C. It is usually given by injection or infusion by trained health professionals.
Brand Name(s)
- PMS-Cytarabine (Canada)
Warning(s)
- Low blood counts (bone marrow suppression): This drug can lower your white blood cells, red blood cells, and platelets. This raises your risk for infection, bleeding, and anemia. Your care team will check your blood often.
- Infection risk: Wash your hands often and avoid people who are sick. Call your care team right away if you have fever, chills, sore throat, cough, sinus pain, painful urination, mouth sores, or a wound that will not heal.
- Bleeding risk: You may bruise or bleed more easily. Use a soft toothbrush and an electric razor. Call your care team if you have black or bloody stools, vomit that looks like coffee grounds, blood in urine, coughing or throwing up blood, bleeding from gums, or unusual vaginal bleeding.
- Stomach and mouth problems: Nausea, vomiting, diarrhea, stomach pain, decreased appetite, and mouth sores can happen. Tell your care team if these do not improve.
- Liver problems: This drug can affect your liver. Tell your team if you have dark urine, yellow skin or eyes, very tired feeling, decreased appetite, upset stomach, or light-colored stools.
- High-dose effects: Severe and sometimes deadly organ problems have happened with high doses in some studies. Your team will watch you closely.
- Benzyl alcohol: Some products contain benzyl alcohol, which can be harmful to newborns and infants. Ask your team if this applies to your situation.
- Vaccines: Talk with your care team before getting any vaccines. Some vaccines may not work well or may raise your risk of infection while on this medicine.
- Tumor lysis syndrome (TLS): Cytarabine can cause TLS, a rapid breakdown of cancer cells. Call right away for fast or irregular heartbeat, fainting, trouble passing urine, muscle cramps or weakness, nausea, vomiting, diarrhea, poor appetite, or unusual tiredness.
- Pregnancy and breastfeeding: This drug may harm an unborn baby. If you can become pregnant, use reliable birth control during treatment. If you become pregnant, tell your care team right away. Tell your team if you are breastfeeding; they will discuss risks to your baby.
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Allergic reactions and other serious symptoms—get help right away if you have:
- Rash; hives; itching; swelling of the face, mouth, lips, tongue, or throat; wheezing; chest or throat tightness; trouble breathing, swallowing, or talking; or unusual hoarseness.
- Shortness of breath, cough, or fever that could signal lung problems.
- Very bad stomach pain; severe diarrhea or constipation; mucus or blood in stools; throwing up blood or coffee-ground vomit.
- Kidney problems: unable to pass urine, change in urine amount, blood in urine, or sudden big weight gain.
- Pancreatitis: very bad stomach or back pain, severe nausea or vomiting.
- Nervous system problems: confusion, mood changes, fever, numbness or tingling in hands or feet, stiff neck, sensitivity to bright light, or very weak muscles.
- Chest pain; severe sleepiness; rapid swelling or sudden weight gain; swelling in arms or legs.
- Severe eye symptoms: vision changes, eye pain, or severe eye irritation.
- Pain, redness, or irritation at the injection site.
- Drug interactions: Tell your doctor and pharmacist about all medicines and supplements you take. Do not start, stop, or change any medicines without checking first.
- Share your medication list: Make sure all your health care providers (doctors, nurses, pharmacists, dentists) know you are taking cytarabine.
Kind of Cancers It Is Used For (not a complete list)
- Acute myeloid leukemia (AML)
- Acute lymphoblastic leukemia (ALL)
- Chronic myeloid leukemia (CML) in blast crisis
- Leukemia or lymphoma that has spread to the brain or spinal fluid (sometimes given into the spinal fluid)
- Sometimes used in certain non-Hodgkin lymphomas, as part of combination chemotherapy
Mechanism of Action
Cytarabine is an antimetabolite, a type of chemotherapy that looks like a normal building block of DNA. Cancer cells take it up and try to use it, but it blocks DNA-making enzymes and stops cells from copying their DNA.
Without the ability to make DNA, rapidly dividing cancer cells die. Normal fast-growing cells (like those in the bone marrow, mouth, gut, and hair) can also be affected, which is why side effects like low blood counts, mouth sores, diarrhea, and hair loss may happen.
Common Side Effects
- Upset stomach, nausea, or vomiting
- Diarrhea or stomach pain
- Decreased appetite
- Mouth irritation or mouth sores
- Feeling tired or weak
- Hair loss
- Muscle or bone pain
These are not all possible side effects. Tell your care team about any symptoms that bother you or do not go away. You can also report side effects to your national health agency.
Learn more about cytarabine on MedlinePlus
Last reviewed: 2025-12-17
