May 25, 2017
Recommended Topic Related To:


"In an article published in the journal Archives of Disease in Childhood, two respiratory specialists claim that doctors are overdiagnosing asthma in children, with inhalers being prescribed needlessly.

According to Asthma UK, 1.1 mill"...




(zileuton tablets)
Tablets Generic Name: zileuton

Please read this leaflet carefully before you start taking ZYFLO® tablets. Also, read it each time you get your ZYFLO prescription refilled.

This leaflet provides important information about taking ZYFLO. It is not meant to take the place of your doctor's specific instructions. Talk to your doctor if you have any questions about ZYFLO. Your doctor or pharmacist can also provide you with additional information about ZYFLO.

What is the most important information I should know about ZYFLO?

The most important things to remember are to take all your doses of ZYFLO every day and to make sure that you return to your doctor's office for scheduled liver enzyme tests.

You should also know that you should seek medical help immediately if you need more “puffs” of your bronchodilator inhaler than normal or if you use the maximum number of “puffs” prescribed for one 24-hour period. These could be a sign of worsening asthma which means that your asthma therapy may need to be changed.

What is ZYFLO?

ZYFLO, which contains the active ingredient zileuton, blocks the formation of certain chemicals (leukotrienes) that may contribute to your asthma symptoms.

Who should not take ZYFLO?

You should not take ZYFLO if you:

  • have active liver disease or have liver enzymes that are elevated.
  • have ever had an allergic reaction to this medicine.

Your doctor will determine if it is safe for you to take ZYFLO.

What should I tell my doctor before I take the first dose of ZYFLO?

You should tell your doctor if you:

  • have ever had liver disease, hepatitis, jaundice (yellow eyes or skin), or dark urine.
  • drink alcohol.
  • are taking any prescription or nonprescription medicines. Your doctor may adjust the doses of some of your other medicines while you are taking ZYFLO.
  • if you are taking theophylline for your asthma, the blood-thinning medication warfarin, or the blood-pressure medication propranolol, your doctor may need to change the doses of these drugs.
  • are pregnant, planning to become pregnant, or are breast-feeding.

How should I take ZYFLO?

  • ZYFLO is taken four times a day with or without food. It may be easier to remember to take ZYFLO if you make it part of your daily routine such as with meals and at bedtime.
  • For ZYFLO to help control your asthma symptoms, it must be taken everyday as prescribed by your doctor. ZYFLO WILL NOT relieve an asthma attack that has already started. While taking ZYFLO, it is important to keep taking your other asthma medicines as directed and to follow all of your doctor's instructions.
  • Even if you have no asthma symptoms, do not decrease the dose of ZYFLO or stop taking the medicine without talking to your doctor first. Feeling good is a sign that the medicine is working.
  • When you take your dose of ZYFLO, the tablets may be swallowed whole or split in half to make them easier to swallow.

What should I avoid while talking ZYFLO?

  • Because ZYFLO may affect how other medications work, always talk to your doctor before you start or stop taking any medicines while taking ZYFLO. This includes all prescription and nonprescription medicines.
  • Never take a larger dose of ZYFLO or take it more often than your doctor has prescribed.
  • It is also important for you to know that it may take several days or a few weeks to get the full benefit from ZYFLO and that you should not stop taking it if you do not feel better right away.

What are the possible side effects of ZYFLO?

All medicines, including ZYFLO, cause side effects in some people. Some of the most common side effects are abdominal pain, upset stomach, and nausea. You should tell your doctor if you experience any new or unusual symptoms while taking ZYFLO.

One side effect that occurs in a small number of patients is an increased release of substances from the liver called “enzymes.” Liver enzymes can be measured by a simple blood test. It is important that your doctor makes sure that your liver enzymes do not become too high and that it is safe for you to continue taking ZYFLO. To insure your safety, your doctor will do this blood test before you first start taking ZYFLO and repeat it on a regular basis while you are taking the medicine.

Usually, even if your liver enzymes are increased, you will not notice any symptoms. However, some symptoms of increased liver enzymes are feeling more tired than normal, “flu-like” symptoms, itching, yellow skin, and/or yellow color in the whites of the eyes, or urine that is darker than normal.

Sleep problems and changes in your behavior can happen while you take ZYFLO. Tell your healthcare provider if you have any sleep problems or changes in behavior.

If you notice these or any other symptoms that you think may be caused by ZYFLO, call your doctor immediately. Once the medicine is stopped, these symptoms usually go away.

Even if you do not have any of these symptoms, you should continue to see your doctor for regular check-ups and liver enzyme tests.

Where should I keep my supply of ZYLFO?

Keep ZYFLO and all medicines out of the reach of children. In case of an accidental overdose, call your doctor or a Poison Control Center immediately.

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

If you would like more information about ZYFLO, ask your doctor or pharmacist. If you have any questions or concerns about taking ZYFLO, discuss them with your doctor.

Revised: June, 2012

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

Zyflo - User Reviews

Zyflo 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 sorted by most helpful. Patient Discussions FAQs

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Allergies & Asthma

Improve treatments & prevent attacks.