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Zafirlukast Side Effects

For the Consumer

Applies to zafirlukast: oral tablet

As well as its needed effects, zafirlukast may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking zafirlukast, check with your doctor immediately:

Less common:
  • Cough or hoarseness
  • fever or chills
  • lower back or side pain
  • pain
  • painful or difficult urination
  • Abdominal or stomach pain
  • clay-colored stools
  • dark urine
  • diarrhea
  • dizziness
  • headache
  • itching
  • loss of appetite
  • nausea
  • rash
  • unpleasant breath odor
  • unusual tiredness or weakness
  • vomiting of blood
  • yellow eyes or skin
Incidence not known:
  • Attack, assault, or force
  • attempts at killing oneself
  • discouragement
  • dry mouth
  • fear or nervousness
  • feeling sad or empty
  • fever with or without chills
  • general feeling of tiredness or weakness
  • hyperventilation
  • irregular heartbeats
  • irritability
  • lack of appetite
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loss of interest or pleasure
  • restlessness
  • seeing, hearing, or feeling things that are not there
  • shakiness in the legs, arms, hands, or feet
  • shortness of breath
  • sleeplessness
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • tiredness
  • trembling or shaking of the hands or feet
  • trouble with concentrating
  • trouble with sleeping
  • unable to sleep
  • unusual bleeding or bruising

Minor Side Effects

Some zafirlukast side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Less common:
  • Acid or sour stomach
  • back pain
  • belching
  • difficulty with moving
  • heartburn
  • indigestion
  • joint pain
  • lack or loss of strength
  • muscle aching or cramping
  • muscle pains or stiffness
  • stomach discomfort or upset
  • swollen joints
  • vomiting
Incidence not known:
  • Hives or welts
  • redness of the skin

For Healthcare Professionals

Applies to zafirlukast: oral tablet


The most commons adverse effects may be associated with headache or gastrointestinal disturbances. These symptoms are usually mild.[Ref]

Nervous system

Very common (10% or more): Headache (up to 12.9%)
Common (1% to 10%): Dizziness (1.6%)
Frequency not reported: Neuropathy, neuropsychiatric events[Ref]


Common (1% to 10%): Nausea (up to 3.1%), diarrhea (up to 2.8%), abdominal pain (up to 2.8%), vomiting (up to 1.5%), dyspepsia (1.3%)[Ref]


In most of the postmarketing reports, the patient's symptoms abated and the liver enzymes returned to normal or near normal after stopping this drug.[Ref]

Common (1% to 10%): SGPT elevation (1.5%), AST (1.4%)
Rare (less than 0.1%): Hyperbilirubinemia without other elevated liver function tests; fulminant hepatitis or progressed to hepatic failure, liver transplantation and death
Postmarketing reports: Symptomatic hepatitis (with or without hyperbilirubinemia) without other attributable cause; hepatic dysfunction[Ref]


Common (1% to 10%): Myalgia (1.6%), back pain (1.5%)
Frequency not reported: Arthralgia[Ref]


Common (1% to 10%): Generalized pain (1.9%), asthenia (up to 1.8%), accidental injury (1.6%), fever (1.4%)
Rare (less than 0.1%): Increased theophylline levels with or without clinical signs or symptoms of theophylline toxicity when this drug was added to an existing theophylline regime.
Frequency not reported: Edema, malaise[Ref]


Common (1% to 10%): Respiratory tract infection (3.5%)[Ref]

Infections were usually mild or moderate, predominantly affecting the respiratory tract and not necessitating withdrawal from the therapy.
In clinical trials, an increased proportion of patients over the age of 55 years reported these infections. Infections occurred equally in both sexes and were associated with coadministration of inhaled corticosteroids.[Ref]


Rare (less than 0.1%): Bleeding disorders including menorrhagia, thrombocytopenia[Ref]


Rare (less than 0.1%): Alopecia
Frequency not reported: Bruising, pruritus[Ref]


Rare (0.01% to 0.1%): Granulomatosis
Very rare (less than 0.01%): Agranulocytosis[Ref]


Systemic eosinophilia may also involve various body systems including vasculitic rash, worsening pulmonary symptoms, cardiac complications or neuropathy.[Ref]

Rare (less than 0.1%): Systemic eosinophilia, eosinophilic pneumonia, or clinical features of vasculitis consistent with Churg-Strauss syndrome[Ref]


Frequency not reported: Urticaria, angioedema, rashes (with or without blistering)[Ref]


Frequency not reported: Insomnia, depression[Ref]


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Accolate (zafirlukast)." Zeneca Pharmaceuticals, Wilmington, DE.

4. Smith LJ, Geller S, Ebright L, Glass M, Thyrum PT "Inhibition of leukotriene D4-induced bronchoconstriction in normal subjects by the oral LTD4 receptor antagonist ICI 204,219." Am Rev Respir Dis 141 (1990): 988-92

5. Spector SL "Leukotriene inhibitors and antagonists in asthma." Ann Allergy Asthma Immunol 75 (1995): 463-70,473-4

6. Findlay SR, Barden JM, Easley CB, Glass M "Effect of the oral leukotriene antagonist, ICI 204,219, on antigen- induced bronchoconstriction in subjects with asthma." J Allergy Clin Immunol 89 (1992): 1040-5

7. Kelloway JS "Zafirlukast: the first leukotriente-receptor antagonist approved for the treatment of asthma." Ann Pharmacother 31 (1997): 1012-21

8. Spector SL, Smith LJ, Glass M "Effects of 6 weeks of therapy with oral doses of ICI 204,219, a leukotriene D4 receptor antagonist, in subjects with bronchial asthma. ACCOLATE Asthma Trialists Group." Am J Respir Crit Care Med 150 (1994): 618-23

9. Torres M, Reddy KR "Severe liver injury." Ann Intern Med 135 (2001): 550

10. Danese S, De Vitis I, Gasbarrini A "Severe Liver Injury Associated with Zafirlukast." Ann Intern Med 135 (2001): 930

11. Wechsler ME, Drazen JM "Zafirlukast and Churg-Strauss syndrome." Chest 116 (1999): 266-7

12. Finkel TH, Hunter DJ, Paisley JE, Finkel RS, Larsen GL "Drug-induced lupus in a child after treatment with zafirlukast (Accolate)." J Allerg Clin Immunol 103 (1999): 533-4

13. Wechsler ME, Garpestad E, Rlier SR, et al. "Pulmonary infiltrates, eosinophilia, and cardiomyopathy following corticosteroid withdrawal in patients with asthma receiving zafirlukast." JAMA 279 (1998): 455-7

14. Wechsler ME, Drazen JM "Zafirlukast and Churg-Strauss syndrome - Reply." JAMA 279 (1998): 1950

15. Knoell DL, Lucas J, Allen JN "Churg-Strauss syndrome associated with zafirlukast." Chest 114 (1998): 332-4

16. Honsinger RW "Zafirlukast and Churg-Strauss syndrome." JAMA 279 (1998): 1949

17. Wechsler M, Drazen JM "Churg-Strauss syndome." Lancet 353 (1999): 1999

18. Churg J, Churg A "Zafirlukast and Churg-Strauss syndrome." JAMA 279 (1998): 1949-50

19. Green RL, Vayonis AG "Churg-Strauss syndrome after zafirlukast in two patients not receiving systemic steroid treatment." Lancet 353 (1999): 725-6

20. Katz RS, Papernik M "Zafirlukast and Churg-Strauss syndrome." JAMA 279 (1998): 1949

It is possible that some side effects of zafirlukast may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.