6 mins read

Overview: Zileuton is used for the long-term treatment of asthma. Common side effects include nausea and upset stomach. Tell your health care provider right away if you get severe nausea or a yellowish color to your skin or the whites of your eyes. Zileuton is used on a regular basis. It will not stop a sudden asthma attack. Always have your rescue inhaler with you.

Uses

What is zileuton used for?

Zileuton is commonly used for the long-term treatment of asthma.

Zileuton may also be used for other conditions as determined by your health care provider.

How does zileuton work (mechanism of action)?

Zileuton helps improve asthma symptoms by blocking substances in the body called leukotrienes that cause inflammation and swelling in the airways.

How is zileuton supplied (dosage forms)?

Brands and other names

  • Zyflo
  • Zyflo CR

Dosage forms and strengths

  • 600 mg extended-release oral tablets
  • 600 mg oral tablets

How should I store zileuton?

Zileuton should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect zileuton from light.

Side Effects

What are the most common side effects of zileuton?

The most common side effects of zileuton are listed below. These side effects may vary depending on the form of zileuton you are taking. Tell your health care provider if you have any of these side effects that bother you.

  • Headache
  • Infection in the nose or throat, sore throat, or common cold symptoms
  • Nausea
  • Diarrhea 
  • Upset stomach or belly pain
  • Muscle aches

There may be other side effects of zileuton that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of zileuton?

While less common, the most serious side effects of zileuton are described below, along with what to do if they happen.

Severe Allergic Reactions. Zileuton may cause allergic reactions, which can be serious. Stop taking zileuton and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Sleep or Mood Problems. Zileuton may cause new or worsened mental health problems that affect your mood, thoughts, feelings, behavior, and general well-being. These effects can occur in people with or without a history of mental health problems and may continue even after stopping zileuton. Tell your health care provider if you have any of the following.

  • Unusual changes in your mood, behavior, or thinking
  • Sleep problems

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking zileuton. Keep all appointments to have your blood checked. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Warnings & Precautions

Who should not use zileuton?

Allergies to Ingredients. People who are allergic to any of the following should not take zileuton.

  • Zileuton
  • Zyflo
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific zileuton products they stock.

Liver Problems. Zileuton should not be used if your liver is not working as well as it should be. If there is a concern about the health of your liver, your health care provider may do tests to see if it is working well enough to take this medicine.

What should I know about zileuton before using it?

Do not take zileuton unless it has been prescribed to you by a health care provider. Take it as prescribed.

Do not share zileuton with other people, even if they have the same condition as you. It may harm them.

Keep zileuton out of the reach of children.

Zileuton is a medicine used on a regular basis and is not to be used when a quick response to breathing problems is needed. Zileuton will not stop a sudden asthma attack. Always have your rescue inhaler with you for asthma attacks.

Do not chew, cut, or crush zileuton extended-release tablets. You should swallow them whole.

What should I tell my health care provider before using zileuton?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if zileuton is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • A history of mental health problems
  • Liver problems
  • A history of drinking alcohol

Other Medicines and Supplements. Zileuton may interact with other medicines and supplements. Before taking zileuton, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how zileuton could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take zileuton while you are pregnant or trying to get pregnant.

If you become pregnant while taking zileuton, you can sign up for the MothersToBaby Pregnancy Studies conducted by the Organization of Teratology Information Specialists. Call 877-311-8972 or visit www.mothertobaby.org/ongoing-study/asthma. This registry collects safety information about the use of asthma medicines during pregnancy.

Breastfeeding. It is not known if zileuton passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should stop breastfeeding or stop zileuton.

Interactions

Does zileuton interact with foods or drinks?

Extended-Release Tablets. Take zileuton extended-release tablets within one hour after your morning and evening meals.

Tablets. Zileuton tablets can be taken with or without food. Making it part of your routine by taking the tablets with meals and at bedtime may help you take them regularly.

It is unknown if drinking alcohol will affect zileuton. The risk of liver problems may increase if you drink large amounts of alcohol while taking zileuton.

Does zileuton interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking zileuton.

  • Warfarin, which is a blood thinner
  • Theophylline (Elixophyllinj, Theo-24), which is a medicine for asthma or certain other breathing problems
  • Propranolol (Inderal LA, Innopran XL), which is a medicine that may be used for certain heart conditions or to lower blood pressure
  • Cyclosporine (Gengraf, Neoral, Sandimmune, and others), which is a medicine that suppresses your immune system

Zileuton may alter the blood levels of many other medicines. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with zileuton. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much zileuton?

If you or someone else has used too much zileuton, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of zileuton?

Extended-Release Tablets. If you miss an extended-release tablet dose, skip the missed dose. Take your next dose at the usual time. Do not take double or extra doses.

Tablets. If you miss a tablet dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.