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Zileuton, Oral zy-LOO-ton

What are other names for this medicine?

Type of medicine: leukotriene receptor antagonist

Generic and brand names: zileuton, oral; Zyflo CR

What is this medicine used for?

This medicine is taken by mouth to treat chronic (long-term) asthma, especially to help prevent asthma attacks. Short, sudden attacks of asthma are treated with other medicines.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

  • an allergic reaction to any medicine
  • liver disease

Tell your healthcare provider if you regularly drink alcohol.

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. It is not known whether this medicine will harm an unborn baby. Do not breast-feed while taking this medicine.

How do I take it?

Check the label on the medicine for directions about your specific dose. Take this medicine every day exactly as directed by your healthcare provider. Take it regularly, even when you do not have any symptoms of asthma. Do not reduce the dosage or stop taking your asthma medicines unless directed by your healthcare provider.

Do not break, crush, or chew these tablets. The extended-release tablets are usually taken 2 times a day, within 1 hour after the morning and evening meal. Swallow them whole.

Do not take this medicine for sudden attacks of asthma. Your healthcare provider will prescribe a different medicine for these attacks. However, continue to take this medicine during acute attacks.

What if I miss a dose?

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

Symptoms of an acute overdose have not been reported.

What should I watch out for?

This medicine will not stop an asthma attack that has already started. Take this medicine as prescribed to help prevent attacks. Keep your quick-relief medicine with you to treat an asthma attack. Contact your healthcare provider if you need to use quick relief medicines more often than usual while you are taking this medicine.

This medicine may affect your liver. You may need to have blood tests regularly. Keep all appointments for blood tests.

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

Also tell your provider if your symptoms do not improve or if your asthma gets worse while you are using this medicine.

If you need emergency care, surgery, or dental work, tell the healthcare provider or dentist you are taking this medicine.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat).

Serious (report these to your healthcare provider right away): The need for medicine for asthma attacks more often than usual, pain on your right side, severe nausea, itching, yellowing of your eyes or skin, dark urine, severe headache, muscle aches and pains, unusual tiredness.

Other: Headache, nausea, dizziness, trouble sleeping, diarrhea, stuffy or runny nose, sore throat.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

  • beta blockers such as acebutolol (Sectral), atenolol (Tenormin), carvedilol (Coreg), labetalol (Trandate), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), pindolol, propranolol (Inderal LA), and sotalol (Betapace)
  • headache medicines such as dihydroergotamine (DHE-45) and ergotamine (Cafergot, Ercaf, Migergot)
  • pimozide (Orap)
  • St. John's wort
  • theophylline
  • warfarin (Coumadin)

If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.


This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.


Developed by RelayHealth.
Medication Advisor 2012.1 published by RelayHealth.
Last modified: 2010-10-19
Last reviewed: 2010-10-18
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2012 RelayHealth and/or its affiliates. All rights reserved.
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