Reviewed on 11/28/2022

What Is Fludarabine and How Does It Work?

Fludarabine is a prescription medication used to treat the symptoms of B-Cell Chronic Lymphocytic Leukemia

  • Fludarabine is available under the following different brand names: Fludara, Oforta

What Are Side Effects Associated with Using Fludarabine?

Common side effects of Fludarabine include:

  • Mild nausea,
  • Loss of appetite,
  • Diarrhea,
  • Mild itching,
  • Skin rash,
  • Headache,
  • Muscle pain, and
  • Tried feeling

Serious side effects of Fludarabine include:

  • Hives,
  • Difficulty breathing,
  • Swelling of the face, lips, tongue, or throat,
  • Fever,
  • Chills,
  • Sore throat,
  • Flu symptoms,
  • Easy bruising,
  • Unusual bleeding (nosebleeds, bleeding gums),
  • Loss of appetite,
  • Nausea,
  • Vomiting,
  • Mouth sores,
  • Unusual weakness,
  • Pale or yellowed skin,
  • Dark-colored urine,
  • Cough with yellow or green mucus,
  • Stabbing chest pain,
  • Shortness of breath,
  • Black, bloody, or tarry stools,
  • Coughing up blood,
  • Lower back pain,
  • Blood in your urine,
  • Urinating less than usual or not at all,
  • Numbness or tingly feeling around the mouth,
  • Fast or slow heart rate,
  • Weak pulse,
  • Fainting,
  • Muscle weakness,
  • Tightness,
  • Contraction,
  • Overactive reflexes,
  • Drowsiness,
  • Mood changes,
  • Increased thirst,
  • Swelling,
  • Rapid weight gain,
  • Vision problems,
  • Headache or pain behind the eyes,
  • Changes in behavior,
  • Confusion,
  • Agitation,
  • Seizure,
  • Severe blistering,
  • Peeling, and
  • Red skin rash

Rare side effects of Fludarabine include:

  • none 

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are the Dosages of Fludarabine?

Adult dosage

Injectable solution

  • 25 mg/mL

Powder for injection

  • 50 mg


  • 10 mg

B-Cell Chronic Lymphocytic Leukemia

Adult dosage

  • 25 mg/sq. Meter Intravenous infusion over 30 minutes once a day for 5 days (up to 30 mg/sq.meter)  
  • 40 mg/sq. meter orally for 5 days
  • Repeat every 28 days

Renal impairment

  • CrCl 30-70 mL/min: reduce by 20%
  • CrCl below 30 mL/min: Intravenous not recommended; orally reduce 50%

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Other Drugs Interact with Fludarabine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Fludarabine?


  • Hypersensitivity 
  • Concomitant pentostatin: risk of fatal pulmonary toxicity
  • IV: severe renal impairment

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Fludarabine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Fludarabine?”


  • Bone marrow depression, renal impairment, elderly
  • Allopurinol and hydration are recommended for patients newly diagnosed with CLL or those at risk of tumor lysis syndrome
  • Very high doses (and rarely, normal doses) have caused irreversible or fatal neurotoxicity manifesting after 21-60 days
  • Risk of potentially fatal autoimmune hemolytic anemia
  • Avoid pregnancy
  • No efficacy in children

Pregnancy and Lactation

  • Use in LIFE-THREATENING emergencies when no safer drug is available.
  • Lactation
    • Not known if excreted in breast milk, do not nurse

Health Solutions From Our Sponsors