Zyflo CR

Zyflo CR is a prescription medication used in maintaining asthma control and preventing asthma attacks. Zyflo CR belongs to a group of drugs called leukotriene receptor antagonists. They prevent leukotrienes from causing inflammation and constriction of airways leading to less asthma symptoms. 

This medication comes in tablets and is usually taken by mouth twice daily within one hour of meals. 

Common side effects of Zyflo CR include infection of the sinuses, nausea, and throat pain. 

Zyflo CR is a prescription medication used in maintaining asthma control and preventing asthma attacks in adults and children 12 years of age and older. 

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

Serious side effects have been reported with Zyflo CR. See the “Zyflo CR Precautions” section.

Common side effects reported by patients using Zyflo CR include the following:

• nose and throat irritation
• sinusitis
• upper respiratory infection
• throat pain
• headache
• muscle aches
• nausea
• diarrhea

This is not a complete list of Zyflo CR side effects. Ask your healthcare provider or pharmacist for more information.

Tell your healthcare provider about any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your healthcare provider if you take:

• theophylline (Theolair)
• warfarin (Coumadin)
• propranolol (Inderal)

This is not a complete list of Zyflo CR drug interactions. Ask your doctor or pharmacist for more information.

Serious side effects have been reported with Zyflo CR include the following:

Liver problems. The use of Zyflo CR may lead to liver damage. Your doctor will monitor your liver enzymes bilirubin during treatment. Tell your healthcare provider about any signs or symptoms of liver damage, which include the following:

• loss of appetite or start losing weight (anorexia)
• nausea or vomiting
• feel tired
• stomach pain or tenderness
• dark urine or light colored stools
• yellowing of your skin or the whites of your eyes
• fever or rash

Sleep disorders and behavior changes. Tell your doctor if you have any sleep problems or changes in behavior.

​Do not use Zyflo CR:

• if you have active liver disease or high liver enzyme levels
• a history of allergic reaction to zileuton or any of the ingredients of Zyflo CR

Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of Zyflo CR, there are no specific foods that you must exclude from your diet when receiving this medication. 

Before taking Zyflo CR, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to Zyflo CR or to any of its ingredients 
• drink alcohol
• have trouble swallowing pills
• have liver problems
• are pregnant or plan to become pregnant
• are breastfeeding or plan to breastfeed

​Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements. 

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

Zyflo CR falls into category C. In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans. Therefore, this medication may be used if the potential benefits to the mother outweigh the potential risks to the unborn child. 

Tell your doctor if you are breastfeeding or plan to breastfeed. 

It is not known if Zyflo CR crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, a choice should be made whether to stop nursing or stop the use of this medication. Your doctor and you will decide if the benefits outweigh the risk of using Zyflo CR. 

Take Zyflo CR exactly as prescribed. 

• Zyflo CR comes in tablet form and is taken twice daily within one hour of morning and evening meals
• Take Zyflo CR regularly as prescribed, even during symptom-free periods
• Do not cut, chew, or crush Zyflo CR tablets
• When taking Zyflo CR, do not decrease the dose or stop taking any other asthma medications unless instructed by a health care provider
• If you miss a dose, take the next dose at the scheduled time and not double the dose.

Tell your doctor if need to use short-acting asthma inhalers more often than usual. Tell your doctor if you need more than the maximum number of inhalations that are prescribed for a 24-hour period.

Zyflo CR does not treat asthma attacks. Make sure you always have a short-acting beta 2-agonist medicine with you. Make sure to use the short-acting beta 2-agonist medicine if a sudden asthma attack happens. 

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

The recommended dose for Zyflo CR for the treatment of asthma is two 600 mg tablets twice daily.

If you take too much of Zyflo CR, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

• Store Zyflo CR at 68°F to 77°F (20°C to 25°C).
• Protect from light.