Zyflo® (zileuton)

Zyflo ® (zileuton) is an oral medication indicated to prevent asthma attacks. It works by blocking the formation of chemicals, called leukotrienes, that cause swelling and tightening of the airways which lead to the onset of asthma symptoms.1-3

Zyflo comes in tablet form. It is part of a preventive and long-term treatment regimen for bronchial asthma. It is not indicated for the relief of an acute asthma attack.

Zileuton is distributed by AstraZeneca Pharmaceuticals in the US.1,2

How does Zyflo (zileuton) work?

Zyflo is a preventive drug. It is not a rescue inhaler and does not provide immediate relief of acute symptoms. Your doctor may also prescribe short-acting bronchodilators for emergency relief of an acute asthma attack.1,2

Zyflo helps reduce airway inflammation.1-3 It works to prevent the development of asthma symptoms including wheezing, coughing, mucus secretion, swelling, tightness in the chest, and shortness of breath.1,2

What is the active ingredient in Zyflo?

The active ingredient in Zyflo is zileuton.1-3

What are some of the possible side effects of Zyflo?

The most common side effects of Zyflo include:1-3

  • Elevated liver enzymes
  • Headache
  • Infection
  • Nausea or upset stomach
  • Diarrhea
  • Generalized pain

Zyflo can cause rare but serious side effects, including:1-3

  • Severe liver problems including pain or tenderness in the right upper side of the stomach area (abdomen)
  • Yellowing of the skin or whites of the eyes
  • Darkening of the urine
  • Serious allergic reactions including rash, swelling of the mouth, tongue, and face
  • Flu-like symptoms including loss of appetite, feeling tired, or sinus discomfort
  • Changes in mood or behavior including insomnia and depression

Things to know

Before starting this medication, you should talk to your doctor about all drugs (prescription and over the counter), supplements, and vitamins you are taking. Some drugs or supplements may interfere with each other. This means both drugs may work less well, or you may have serious side effects. While taking Zyflo your doctor may adjust the doses of some of the other drugs you take.

In particular, zileuton may interact with categories of drugs including:1-3

  • Certain blood thinners
  • Certain blood pressure medications
  • Certain other asthma medications like theophylline

Before starting treatment with Zyflo, discuss all of your health conditions with your doctor, especially:1-3

  • Hypersensitivity to zileuton
  • Liver problems
  • Drink substantial quantities of alcohol

Your doctor may recommend liver enzyme test monitoring on a regular basis. Do not take Zyflo if you have active liver disease or elevated transaminase levels.

Zyflo is indicated for the treatment of asthma in adults and children over age 12.1-3 Tell your doctor if you are pregnant or plan to become pregnant. Zyflo should be used during pregnancy and breastfeeding only if the potential benefit justifies any potential risks to the baby.1-3

Dosing information for zileuton

Be sure to talk to your doctor if you have any questions about your medication regimen.1,2

View full prescribing information.

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Last reviewed: April 2020.