May 24, 2017
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Zyflo CR

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Zyflo CR


(zy"-flo) CR
(rileuton) extended-release tablets

Read the Patient Information that comes with ZYFLO CR carefully before you start taking it and read it each time you get a refill.

There may be new information. This leaflet does not take the place of talking with your health care provider about your medical condition or your treatment.

What is ZYFLO CR?

ZYFLO CR is a medicine that is used to prevent asthma attacks and for long-term management of asthma in adults and children 12 years of age and older. ZYFLO CR blocks the production of leukotrienes. Leukotrienes are substances that may contribute to your asthma.

ZYFLO CR is not a rescue medicine (it is not a bronchodilator) and should not be used if you need relief right away for an asthma attack.

Who should not take ZYFLO CR?

Do not take ZYFLO CR if you have:

  • active liver disease or repeated blood tests showing elevated liver enzymes (substances released by the liver).
  • ever had an allergic reaction to ZYFLO CR or any of the ingredients in ZYFLO CR.

What should I tell my health care provider before taking ZYFLO CR?

ZYFLO CR may not be right for you. Tell your health care provider if you:

  • have ever had liver problems, including hepatitis, jaundice (yellow eyes or skin), or dark urine.
  • drink alcohol. Tell your health care provider how much and how often you drink alcohol.
  • have difficulty swallowing pills.
  • are pregnant or planning to become pregnant. It is not known if ZYFLO CR will harm your unborn baby. Do not take ZYFLO CR during pregnancy unless you and your health care provider decide that taking the medicine is more important than the possible risk to your unborn baby.
  • are breastfeeding. It is not known if ZYFLO CR passes into your breast milk. You and your health care provider should decide if you will take ZYFLO CR or breastfeed. You should not do both.

Tell your health care provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. ZYFLO CR and other medicines may affect each other causing side effects. Your health care provider may need to adjust the doses of certain medicines while you are taking ZYFLO CR. Talk with your health care provider before starting or stopping any prescription or nonprescription medicine.

Know the medicines you take. Keep a list of your medicines and show it to your health care provider and pharmacist when you get a new medicine.

How should I take ZYFLO CR?

  • Take ZYFLO CR exactly as prescribed by your health care provider. Do not decrease the dose of ZYFLO CR or stop taking the medicine without talking to your health care provider first, even if you have no asthma symptoms.
  • Take two ZYFLO CR tablets two times each day within one hour after your morning and evening meals.
  • Swallow ZYFLO CR whole. Do not chew, cut or crush ZYFLO CR tablets. Tell your health care provider if you cannot swallow the tablets whole.
  • Follow your health care provider's instructions for what to do if you get sudden symptoms of an asthma attack. You can continue taking ZYFLO CR during asthma attacks.
  • Get medical help right away if you need to use your rescue medicine more often than usual or if you use the highest number of 'puffs' prescribed for one 24-hour period. These could be signs that your asthma is getting worse. This means that your asthma therapy may need to be changed.
  • Keep taking your other asthma medicines as directed while taking ZYFLO CR.
  • If you miss a dose, just take your next scheduled dose when it is due. Do not double the dose.
  • If you take too much ZYFLO CR, call your health care provider or a Poison Control Center right away.

What are the possible side effects of ZYFLO CR?

ZYFLO CR can cause serious side effects.

Liver problems. Liver function enzymes and bilirubin can increase while taking ZYFLO CR, and severe liver injury can occur. Sleep disorders and changes in your behavior can happen while you take ZYFLO CR. Tell your healthcare provider if you have any sleep problems or changes in behavior.

Keep all of your health care provider's appointments and be sure to follow all of your health care provider's instructions. Have your blood tests done as ordered to check your liver enzymes.

Allergic reactions can happen while taking ZYFLO CR. Tell your health care provider right away if you get any of the following signs or symptoms: rash or hives.

Tell your health care provider if you have any new or unusual symptoms that bother you or do not go away while taking ZYFLO CR. These are not all of the possible side effects of ZYFLO CR. For more information, ask your health care provider or pharmacist.

How should I store ZYFLO CR?

  • Store ZYFLO CR between 68°F and 77°F (20°C-25°C).
  • Protect ZYFLO CR from light and replace the cap each time after use.

Keep ZYFLO CR and all medicines out of the reach of children.

General Information about ZYFLO CR:

Medicines are sometimes prescribed for conditions that are not mentioned in the patient leaflet. Do not use ZYFLO CR for a condition for which it was not prescribed. Do not give ZYFLO CR to other people, even if they have the same symptoms you have. It may harm them.

This patient information leaflet summarizes the most important information about ZYFLO CR. If you would like more information about ZYFLO CR, talk with your health care provider or pharmacist. You can ask your health care provider or pharmacist for information about ZYFLO CR that is written for health professionals.

For more information go to or call 1-888-661-9260.

What are the ingredients in ZYFLO CR?

Active ingredient: zileuton

Inactive ingredients: crospovidone, ferric oxide, glyceryl behenate, hydroxypropyl cellulose, hypromellose, magnesium stearate, mannitol, microcrystalline cellulose, povidone, pregelatinized starch, propylene glycol, sodium starch glycolate, and talc.

Last reviewed on RxList: 11/29/2016
This monograph has been modified to include the generic and brand name in many instances.

Zyflo CR - User Reviews

Zyflo CR User Reviews

Now you can gain knowledge and insight about a drug treatment with Patient Discussions.

Here is a collection of user reviews for the medication Zyflo CR sorted by most helpful. Patient Discussions FAQs

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