Zafirlukast - Oral

What Is Zafirlukast?

Zafirlukast is an oral prescription tablet used for the long-term management of asthma.

Accolate, the brand version of zafirlukast, is no longer available in the United States. However, the generic form of zafirlukast is available, and the brand formulation is available outside the United States.

Zafirlukast controls asthma symptoms by reducing inflammation, edema (fluid), and airway narrowing. It is a selective peptide leukotriene receptor antagonist (LTRA) that binds to the leukotriene receptors in the lungs and prevents their activation.

Drug Facts

Generic Name: Zafirlukast

Administration Route(s): Oral

Drug Availability: Prescription

Therapeutic Classification: Anti-inflammatory

Available Generically: Yes

Controlled Substance: N/A

Active Ingredient: Zafirlukast

Dosage Form(s): Tablet

What Is Zafirlukast Used For?

The Food and Drug Administration approved zafirlukast for long-term prevention of asthma symptoms in adults and children aged 5 years and older.

Zafirlukast does not treat acute asthma symptoms as they are happening, and it will not stop an ongoing asthma attack.

Zafirlukast Drug Information

Verywell / Dennis Madamba

How to Take Zafirlukast 

Take your prescribed dose of zafirlukast twice a day, at least one hour before or two hours after meals. Do not take it with food. Food can reduce the bioavailability of zafirlukast, which affects how the medication is absorbed in the body.


Store zafirlukast in its original container, and keep it away from the reach of children or pets. Keep it at a room temperature of 68 F to 77 F, and away from light or moisture.

Off-Label Uses

Healthcare providers can prescribe zafirlukast off-label for treating several conditions that are caused by severe inflammation. Off-label use means a drug is prescribed for a condition that it is not approved to treat.

Off-label uses of zafirlukast include:

  • Chronic itching and hives
  • Inflammatory lung disease
  • Capsule contracture, a type of inflammatory scarring that can occur after breast augmentation

Zafirlukast has also been studied in experimental research for its effects on Alzheimer’s dementia, with promising results, although it is not prescribed for treating this condition.

How Long Does Zafirlukast Take to Work?

It can take up to a week or longer for this medication to begin having a therapeutic effect.

What Are the Side Effects of Zafirlukast?

This is not a complete list of side effects, and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at or 1-800-FDA-1088.

Zafirlukast can cause several different side effects, some of which are mild and tolerable, and some of which are serious. It is important to be aware of the potential side effects and talk to your healthcare provider about what to do if you or your child experiences them.

Common Side Effects

The most common side effects of zafirlukast are:

  • Headaches 
  • Infection 
  • Nausea 
  • Diarrhea 
  • Insomnia 
  • Back pain
  • Muscle weakness

Discuss these issues with your healthcare provider rather than putting up with them. Often, lifestyle methods or medications can help alleviate these side effects. If they are interfering with your quality of life, your provider might change your prescription.

Severe Side Effects

Zafirlukast is typically well tolerated, without complications. But, in rare instances, it can cause serious side effects with potentially harmful effects on your health.

Serious side effects include:

  • Hypersensitivity reactions, which can cause severe itching, rash, blisters, and/or angioedema (a type of swelling)
  • Depression, which can cause sadness, appetite changes, sleep pattern changes, and/or diminished motivation
  • Liver damage, which can cause nausea, tiredness, and yellow discoloration of the skin and eyes
  • Spasm of the airways, which can cause difficulty breathing
  • Systemic eosinophilia, eosinophilic pneumonia, or vasculitis, which are inflammatory conditions
  • Churg Strauss syndrome, an inflammatory condition that causes vasculitis (inflammation of the blood vessels) and is often treated with systemic steroid therapy

If left untreated, these conditions can rapidly worsen. Often, treatment will help resolve these complications. Your healthcare provider will likely switch you to a different asthma treatment if you develop any of the serious side effects of zafirlukast.

Long-Term Side Effects

This medication should not continue to cause additional problems after you stop taking it. However, long-term problems can occur if you develop organ damage due to side effects while taking it. For example, it may take a long time for your liver to recover from damage.

Report Side Effects

Zafirlukast may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Zafirlukast Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):
    • For asthma:
      • Adults and children 12 years of age and older—20 milligrams (mg) two times a day.
      • Children 5 to 11 years of age—10 mg two times a day.
      • Children younger than 5 years of age—Use and dose must be determined by your doctor.


Older adults (aged 65 years and older) and children aged between 5 and 11 years old may need a lower-than-standard dose of zafirlukast.

Missed Dose

If you miss your dose of zafirlukast, try to take it as soon as possible. If it is close to the time for your next dose, you should take your next dose without doubling up and then resume your regular schedule.

Overdose: What Happens If I Take Too Much Zafirlukast?

Taking too much zafirlukast can cause a rash or upset stomach.

Your healthcare provider would observe you for symptoms of an overdose and give you treatment for your symptoms as needed.

Sometimes the medication can be removed from the stomach with gastric lavage.² This is a procedure in which a tube is placed into the mouth and advanced to the stomach to remove the contents before they are absorbed in the body.

What Happens If I Overdose on Zafirlukast?

If you think you or someone else may have overdosed on zafirlukast call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking zafirlukast, call 911 immediately.


Drug Content Provided and Reviewed by IBM Micromedex®

It is very important that your doctor check the progress of you or your child at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

You or your child may be taking other medicines for asthma along with zafirlukast. Do not stop taking or reduce the dose of the other medicines, even if your asthma seems better, unless you are told to do so by your doctor.

Check with your doctor if your or your child's symptoms do not improve or if your asthma gets worse.

Stop using this medicine and check with your doctor right away if you or your child have pain or tenderness in the upper stomach; pale stools; dark urine; loss of appetite; nausea; unusual tiredness or weakness; or yellow eyes or skin. These could be symptoms of a serious liver problem.

This medicine may cause a rare blood condition called Churg-Strauss syndrome. This usually occurs in patients who have asthma or are taking oral steroid medicines that is being stopped or the dose is being reduced or lowered. Tell your doctor right away if you or your child have the following symptoms: a feeling of pins and needles, flu-like symptoms, numbness of the arms or legs, rash, or pain and swelling of the sinuses.

This medicine may cause some people to be agitated, disoriented, irritable, or display other abnormal behaviors. It may also cause some people to have suicidal thoughts and tendencies or to become more depressed and have problems with sleep. If you, your child, or your caregiver notice any of these side effects, tell your doctor or your child's doctor right away.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

What Are Reasons I Shouldn’t Take Zafirlukast?

You should not take this medication if you have ever had an allergic reaction to it, or have impaired liver function or liver damage.

What Other Medications Interact With Zafirlukast?

Zafirlukast has several medication interactions. If you take a medication that interacts with zafirlukast, your healthcare provider might adjust the doses or monitor for side effects.

Interactions include:

What Medications Are Similar?

There are many medications prescribed for the treatment of asthma with a variety of different mechanisms. Some medications are prescribed as part of combination therapy. 

Like zafirlukast, Singulair (montelukast) and Zyflo (zileuton) are LTRAs used for the treatment of asthma.

Frequently Asked Questions

  • What is zafirlukast used for?

    Zafirlukast is used as maintenance therapy for asthma to prevent symptoms and asthma attacks.

  • How does zafirlukast work?

    This medication prevents inflammation, airway narrowing, and fluid in the lungs by binding to the leukotriene receptors and preventing their action. It is a selective peptide leukotriene receptor antagonist (LTRA).

  • What drugs should not be taken with zafirlukast

    This medication can increase the effects of warfarin. Additionally, taking aspirin, fluconazole, theophylline, or erythromycin can alter the effects of zafirlukast.

  • What are the side effects of zafirlukast?

    The most common side effects include headaches, infections, nausea, diarrhea, and insomnia. Serious side effects can include an allergic reaction, inflammation, liver damage, depression, or difficulty breathing.

  • How do I safely stop taking zafirlukast?

    Don’t stop taking this medication suddenly unless your healthcare provider instructs you to do so. You may need to gradually decrease your dose as you start using a new asthma treatment.

How Can I Stay Healthy While Taking Zafirlukast

Make sure that you’re aware of the potential side effects while taking zafirlukast, and get medical attention if you experience signs of a serious side effect.

You can also use lifestyle strategies to help manage your asthma. This includes identifying and avoiding your asthma triggers, such as foods, environmental substances, and more.

Additionally, be sure to tell your doctor or pharmacist before you start any new medications, supplements, or herbs while you are taking zafirlukast.

Medical Disclaimer

Verywell Health's drug information is meant for education purposes only and not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Food and Drug Administration. Accolate (zafirlukast) Tablets. Updated November 2013.

  3. Generali JA, Cada DJ. Zafirlukast: chronic urticaria. Hosp Pharm. 2015 Nov;50(10):873-875. doi:10.1310/hpj5010-873

  4. Meshram D, Bhardwaj K, Rathod C, et al. The role of leukotrienes inhibitors in the management of chronic inflammatory diseases. Recent Pat Inflamm Allergy Drug Discov. 2020;14(1):15-31. doi:10.2174/1872213X14666200130095040

  5. Headon H, Kasem A, Mokbel K. Capsular contracture after breast augmentation: An update for clinical practice. Arch Plast Surg. 2015 Sep;42(5):532-43. doi:10.5999/aps.2015.42.5.532

  6. Xiong LY, Ouk M, Wu CY, et al. Leukotriene receptor antagonist use and cognitive decline in normal cognition, mild cognitive impairment, and Alzheimer's dementia. Alzheimers Res Ther. 2021 Sep 3;13(1):147. doi:10.1186/s13195-021-00892-7

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.