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pronounced as (ee flor' ni theen)

Why is this medication prescribed?

Eflornithine is used to treat a certain type of neuroblastoma (a cancer that begins in nerve cells) in adults and children who have completely responded or partially responded to other treatments. Eflornithine is in a class of medications called ornithine decarboxylase (ODC) inhibitors. It works by blocking the action of a substance that signals cancer cells to multiply. This helps stop or slow the spread of cancer cells.

How should this medicine be used?

Eflornithine comes as a tablet to take by mouth. It is usually taken with or without food twice a day. Take eflornithine at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take eflornithine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you are unable to swallow the tablet(s), you may chew the tablet(s) or you may crush the tablet(s) and mix with 2 tablespoons of soft food or liquid. Eat or drink the mixture right away or within 1 hour of mixing. If any crushed tablet pieces remain, mix with another 2 tablespoons of soft food or liquid, and swallow the entire mixture to make sure you have taken all of the medication.

If you vomit after taking eflornithine, do not take another dose. Continue your regular dosing schedule.

Your doctor may decrease your dose of eflornithine, treat you with other medications, or interrupt or stop your treatment if you experience certain side effects. Be sure to tell your doctor how you are feeling during your treatment with eflornithine.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking eflornithine,

  • tell your doctor and pharmacist if you are allergic to eflornithine, any other medications, or any of the ingredients in eflornithine tablets. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor if you have or have ever had hearing problems, a low number of red or white blood cells or platelets, or liver problems.
  • tell your doctor if you are pregnant, plan to become pregnant, or plan to father a child. You or your partner should not become pregnant during your treatment with eflornithine. If you are a female that can become pregnant, you will need to have a pregnancy test before you begin treatment, and you should use effective birth control during your treatment and for 1 week after your final dose. If you are a male with a female partner that can become pregnant, use effective birth control during your treatment and for 1 week after your final dose. If you or your partner become pregnant while taking eflornithine, call your doctor. Eflornithine may harm the fetus.
  • tell your doctor if you are breast-feeding or plan to breastfeed. Your doctor may tell you not to breast-feed during your treatment and for 1 week after your final dose.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking eflornithine.
  • you should know that eflornithine may cause serious hearing problems. Hearing loss may be severe and may require hearing aids. You will need to have a hearing exam before you start taking eflornithine and at least every 6 months during your treatment with eflornithine. Call your doctor right away if you have any of the following symptoms: new or worsening hearing loss or ringing in the ears.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget a dose?

Take the missed dose as soon as you remember it. However, if it is within 7 hours of the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medication cause?

Eflornithine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • runny nose, sneezing, and congestion
  • diarrhea
  • vomiting
  • burning, red, itchy, crusty, or irritated eyes
  • rash
  • arm or leg pain
  • hair loss
  • ear pain or other signs of ear infection

Some side effects can be serious. If you experience any of these symptoms or those listed in the SPECIAL PRECAUTIONS section, call your doctor immediately:

  • fever, chills, cough, sore throat, difficulty urinating, pain when urinating, or other signs of infection
  • warm, red, or painful skin; or sores on the skin
  • unusual bruising or bleeding
  • blood in urine or stool
  • pale skin
  • unusual tiredness or weakness
  • shortness of breath
  • yellowing of the skin or eyes, dark-colored (tea-colored) urine, light-colored stools, pain in upper right part of the stomach, nausea, vomiting, or loss of appetite

Eflornithine may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests before and during your treatment to check your body's response to eflornithine.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Iwilfin®
Last Revised - 02/15/2024