Skip to Content

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.

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

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

Nervous system

Nervous system side effects have included headache, asthenia, somnolence, dizziness, fever, insomnia, and pain.[Ref]


A 47-year-old man with persistent asthma developed sinus congestion, cough, malaise, arthralgia, a progressive rash over his trunk and extremities, and fever within one month of reinitiating zafirlukast therapy. Prior to the development of these symptoms, the patient had been receiving inhaled steroids in combination with zafirlukast therapy. A skin eruption was observed on his face, arms, and trunk. A chest film showed basilar reticulonodular infiltrates, and laboratory findings revealed a positive titer for rheumatoid factor, a blood eosinophil count of 4,350 and an elevated total IgE level (851 intl units/L). The patient's prior medications were discontinued, and he was treated with intravenous hydrocortisone, acyclovir, ceftriaxone, and erythromycin. The patient demonstrated rapid improvement of all signs and symptoms following initiation of hydrocortisone. A causal relationship between zafirlukast therapy and the development of systemic vasculitis was suspected.

Following nearly two months of zafirlukast therapy, a 53-year-old female with a history of asthma and chronic sinusitis developed arthralgias involving her knees, wrists, shoulder and joints. She further developed amaurosis fugax and a hemorrhagic, maculopapular eruption on her elbows and fingers. Her chest film showed multiple pulmonary nodes, and a bronchoscopic lung biopsy revealed eosinophilic infiltrates and granulomas. The patient was initiated on high-dose steroid therapy after which all signs and symptoms promptly resolved. It was believed that this case report represented zafirlukast-induced Churg-Strauss syndrome independent of steroid therapy.[Ref]

Immunologic side effects have included Churg-Strauss syndrome, also known as allergic granulomatosis, and drug-induced lupus. In addition, increased incidence of infection in patients over the age of 55 has been noted in clinical trials of patients receiving zafirlukast.[Ref]


Gastrointestinal side effects have included dry mouth, nausea, diarrhea, abdominal pain, vomiting and dyspepsia.[Ref]


Musculoskeletal side effects have included arthralgia, myalgia and back pain.[Ref]


In clinical trials, SGPT elevations were comparable between treatment and placebo groups. However, one case of hepatitis and hyperbilirubinemia was observed in a patient receiving zafirlukast 40 mg per day for 100 days.[Ref]

Hepatic side effects have included elevations of hepatic transaminase levels.[Ref]


General side effects have included malaise.[Ref]


Dermatologic side effects have included pruritus.[Ref]


Psychiatric side effects have included insomnia and depression.


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

2. 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

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

4. 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

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

6. 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

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

8. 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

9. 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

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

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

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

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

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

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

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

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

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

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.