Home What Is Zafirlukast?

What Is Zafirlukast?

Uses, Side Effects, Dosage & FAQs (2026 Guide)

Written by: Mariah Powers Medically reviewed by: Andy Acevedo, PharmD Last Updated:

Zafirlukast is an oral medication for long-term asthma management.

Providers typically prescribe this daily pill to help improve lung function and reduce the frequency of asthma symptoms over time. It is designed as a maintenance therapy for chronic asthma and is not intended to treat sudden asthma attacks.

How It Works

Zafirlukast belongs to a class of medications known as leukotriene receptor antagonists. It works by blocking leukotrienes, which are inflammatory chemicals that cause airway tightening, swelling, and mucus production. By limiting leukotriene production, zafirlukast helps reduce airway inflammation and decrease asthma symptoms.

Quick Facts
Common Brands Accolate
Drug Class Leukotriene receptor antagonist
Generic Status Generic is available
Availability Prescription only

Dosing

Zafirlukast is taken orally and is typically available in 10 mg and 20 mg tablets. The standard dosage is 20 mg taken by mouth twice daily. 

Take this medication at the same time every day on an empty stomach at least 1 hour before or 2 hours after a meal.

Note: Dosing information below is educational only. Your prescribing physician will determine your specific dose based on your individual health needs. Always follow your healthcare provider’s instructions for exact dosing.

Uses

FDA-Approved Uses

Zafirlukast is FDA-approved for long-term treatment of chronic asthma.

Off-Label Uses

You may see Zafirlukast prescribed for uses that are not “FDA-approved.” This is a common and legal practice called “off-label” prescribing, where a doctor uses their clinical judgment to prescribe a drug for a different (but well-researched) purpose.

While doctors may consider zafirlukast to treat other conditions, it has no widespread off-label uses.

Side Effects


Like all medications, zafirlukast can cause side effects. Some common side effects may improve over time as your body adjusts to the medication. Other side effects may be serious and require medical attention.

Common Side Effects

  • Headache
  • Nausea
  • Diarrhea
  • Vomiting
  • Abdominal pain
  • General pain
  • Back pain
  • Dizziness
  • Weakness
  • Fever
  • Infection

Serious Side Effects

Serious side effects are rare, but it’s important to know what to look for if they do occur. Contact your doctor or seek medical care if you have signs of a severe reaction to zafirlukast.

  • Allergic reactions: An allergic reaction to zafirlukast can include trouble breathing, wheezing, hives, skin rash, or severe swelling of the face, lips, tongue, or throat.
  • Liver damage (hepatotoxicity): Signs of liver issues may include right upper stomach pain, extreme tiredness, persistent nausea or vomiting, loss of appetite, dark urine, light-colored stool, or yellowing of the skin and whites of the eyes (jaundice).
  • Mood and behavior changes: Individuals may experience new or worsened mental health symptoms such as depression, anxiety, agitation, hostility, hallucinations, trouble sleeping, or thoughts of self-harm.
  • High eosinophil levels: A rare increase in these white blood cells can lead to inflamed blood vessels, causing symptoms like intense itching, rash, shortness of breath, sinus pain, or tingling in the arms, hands, legs, or feet.

Call your doctor immediately if you experience any concerning or prolonged symptoms.

Pharmacist Tips

Keep A Rescue Inhaler Accessible

Standard guidelines suggest keeping a rapid-acting rescue inhaler (like albuterol) available, as zafirlukast will not provide relief during a sudden asthma attack.

Take Daily As Prescribed

Providers typically recommend taking zafirlukast every day as prescribed, even during periods when you don’t have asthma symptoms.

Take On An Empty Stomach

Guidelines indicate that zafirlukast should be taken on an empty stomach because food impairs the body’s ability to absorb the drug. In practice, this means taking zafirlukast at least 1 hour before or 2 hours after meals.

Store Properly

Store the tablets at room temperature in a cool, dry place within their original container, and protect them from light and excessive moisture.

Drug Interactions

Certain medications and substances can interact with zafirlukast, potentially altering how it works or increasing the risk of side effects.

  • Blood thinners: Taking zafirlukast with warfarin (Coumadin) can increase the risk of bleeding. Taking these drugs together may require closer monitoring of blood coagulation and dosage adjustments.
  • Seizure medications: Interactions may occur between zafirlukast and antiseizure drugs such as phenytoin (Dilantin) and carbamazepine (Tegretol), potentially decreasing the effect of both when co-administered
  • Antibiotics and antifungals: Medications such as erythromycin, clarithromycin, and fluconazole (Diflucan) can interact with zafirlukast by increasing levels in the body and the potential for side effects.
  • Heart and blood pressure medications: Interactions are possible with calcium channel blockers (such as amlodipine, nifedipine, diltiazem, felodipine, verapamil) and antiarrhythmics (like dofetilide and quinidine).
  • Immunosuppressants: Drugs that affect the immune system, such as cyclosporine (Gengraf, Neoral), may interact with zafirlukast.
  • Food: Taking zafirlukast with food reduces its absorption and may impact its effectiveness.

Always give your doctor and pharmacist a complete list of all your medications, vitamins, and supplements to check for potential interactions.

FAQs

Why do I absolutely have to take zafirlukast on a completely empty stomach?

Food can affect how well the body absorbs zafirlukast. Taking zafirlukast with a meal can reduce absorption of the active ingredient, which may diminish its ability to manage asthma symptoms. Sandard guidelines suggest taking zafirlukast at least 1 hour before eating or 2 hours after finishing a meal.

Is zafirlukast a rescue medication I can use when I’m having an asthma attack?

Zafirlukast is not a rescue medication and will not relieve sudden breathing problems. It is a long-term maintenance therapy designed to maintain breathing improvements over time. Providers typically recommend carrying a fast-acting rescue inhaler (such as albuterol) for emergency relief.

What is the real difference between zafirlukast and montelukast?

Zafirlukast and montelukast (Singulair) are in the same class of drugs (leukotriene receptor antagonists) for asthma control, but there are notable differences between them. Zafirlukast is usually taken twice daily on an empty stomach, while montelukast is taken once a day with or without food. Additionally, montelukast is commonly used for seasonal allergies and exercise-induced asthma, but zafirlukast is used for treating chronic asthma.

Can taking zafirlukast cause anxiety or sudden mood changes?

Zafirlukast may cause new or worsening mental health issues. Some individuals have reported changes in mood or behavior, including feelings of anxiety, nervousness, agitation, depression, difficulty sleeping, or thoughts of self-harm. Contact a healthcare provider immediately if you notice any sudden changes in mood while taking zafirlukast.

Is it safe to take an allergy pill (like Zyrtec or Claritin) at the same time as zafirlukast?

Pharmacists recommend consulting with your prescribing doctor before taking any allergy pills alongside zafirlukast. Your doctor can address whether any other medications, including over-the-counter drugs, are safe to use with zafirlukast.

Can I drink alcohol while taking zafirlukast?

It is currently unknown if drinking alcohol affects zafirlukast. Your doctor can offer personalized guidance about alcohol consumption while managing chronic asthma.

How long does it take for zafirlukast to improve my asthma symptoms?

Zafirlukast works gradually to improve lung function. Guidelines suggest taking zafirlukast for at least 1 to 2 months before your doctor can assess its effectiveness. Clinical studies have shown improvements in asthma symptoms after approximately 3 months.

Is it safe to use zafirlukast if I am currently pregnant or breastfeeding?

Your provider can help you weigh the risks and benefits of this medication during pregnancy. For nursing mothers, the drug manufacturer does not recommend taking zafirlukast because the medication may pass into breast milk.

Do I have to use my daily steroid inhaler with zafirlukast?

Standard guidelines recommend continuing to use prescribed inhaled corticosteroids unless otherwise instructed by a healthcare provider. Zafirlukast is commonly prescribed when inhaled steroids alone are not providing adequate asthma control.

Can I cut or crush the zafirlukast tablet if I have a hard time swallowing pills?

Zafirlukast is a tablet intended to be swallowed whole. Consult your doctor or pharmacist if you have difficulty swallowing the tablets.

What happens if I eat a heavy meal right after taking my dose of zafirlukast?

If a heavy meal is consumed too close to taking a dose of zafirlukast, the food can interfere with the drug’s absorption. This can reduce the amount of active medication entering the bloodstream, potentially making treatment less effective. For this reason, guidelines stipulate that you should take zafirlukast at least 1 hour before eating or at least 2 hours after a meal.

Does zafirlukast help clear up my seasonal allergies, too?

Zafirlukast is primarily used to treat chronic asthma. It is not FDA-approved as a treatment for seasonal allergy symptoms.

Will I have to take zafirlukast indefinitely?

Zafirlukast is intended for long-term management of chronic asthma. Providers typically recommend taking the medication daily, even in the absence of symptoms, to enhance lung function and prevent future asthma attacks. Your doctor will regularly evaluate the ongoing need for this or any asthma therapy.

Comparable Medications

Zafirlukast, Montelukast (Singulair), Zileuton (Zyflo), Albuterol (ProAir / Ventolin), Budesonide (Pulmicort)?

This is a once-daily oral leukotriene receptor antagonist that can be taken with or without food. It may be prescribed to treat asthma, including exercise-induced asthma, and allergies.


Zileuton

Zileuton is a 5-lipoxygenase inhibitor, which is designed to reduce airway inflammation.


Albuterol is a fast-acting rescue inhaler utilized for immediate relief during sudden asthma attacks.


Budesonide

This medication is an inhaled corticosteroid commonly used to reduce airway inflammation.

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Important: Information on this page is for educational purposes only. Prescribing decisions are made by independent, licensed providers. TelyRx operates technology-enabled pharmacies and a telehealth platform that connects patients with board-certified licensed providers. Prescriptions, when provider-approved and issued, are filled and shipped by TelyRx-affiliated pharmacies. We do not employ physicians or make prescribing decisions. Learn more about our editorial standards here.