Brand Names: Zyflo CR

Generic Name: zileuton (Pronunciation: zye LOO ton)

• What is zileuton (Zyflo CR)?
• What are the possible side effects of zileuton (Zyflo CR)?
• What is the most important information I should know about zileuton (Zyflo CR)?
• What should I discuss with my healthcare provider before taking zileuton (Zyflo CR)?
• How should I take zileuton (Zyflo CR)?
• What happens if I miss a dose (Zyflo CR)?
• What happens if I overdose (Zyflo CR)?
• What should I avoid while taking zileuton (Zyflo CR)?
• What other drugs will affect zileuton (Zyflo CR)?
• Where can I get more information?

What is zileuton (Zyflo CR)?

Zileuton is a leukotriene (loo-koe-TRY-een) inhibitor. Leukotrienes are chemicals your body releases when you breathe in an allergen (such as pollen). These chemicals cause swelling in your lungs and tightening of the muscles around your airways, which can result in asthma symptoms.

Zileuton is used to prevent asthma attacks in adults and children as young as 12 years old.

Zileuton may also be used for other purposes not listed in this medication guide.

What are the possible side effects of zileuton (Zyflo CR)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have any of these serious side effects:

• nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);
• skin rash, bruising, severe tingling, numbness, pain, muscle weakness;
• mood or behavior changes, anxiety, depression, or thoughts about suicide or hurting yourself; or
• worsening asthma symptoms.

Less serious side effects may include:

• cold symptoms such as stuffy nose, sinus pain, sneezing, sore throat;
• headache;
• diarrhea, upset stomach;
• weakness; or
• muscle pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the Zyflo CR (zileuton extended release tablets) Side Effects Center for a complete guide to possible side effects »

What is the most important information I should know about zileuton (Zyflo CR)?

Call your doctor at once if you have nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes). These may be early signs of liver problems.

Do not use zileuton to treat an asthma attack that has already begun. It will not work fast enough to reverse your symptoms. Use only a fast-acting inhalation medication to treat an asthma attack. Talk with your doctor if any of your asthma medications do not seem to work as well in treating or preventing asthma attacks.

It may take up to a few weeks of using this medicine before your symptoms improve. For best results, keep using zileuton as directed, even if you feel fine. Having no asthma symptoms is a sign that the medication is working.

Call your doctor right away if you feel that this medicine is not working as well as usual, or if it makes your condition worse. If it seems like you need to use more of any of your medications in a 24-hour period, talk with your doctor.

Avoid drinking alcohol while you are taking zileuton. Alcohol can increase your risk of liver damage.

Call your doctor at once if you have any mood or behavior changes, anxiety, depression, or thoughts about suicide or hurting yourself.