OpenClaim

Zafirlukast Side Effects

The most commonly reported side effects of zafirlukast include dyspnoea, asthma, and fatigue, based on 2,524 FDA adverse event reports from 2004 to 2025. 4.7% of reports found the drug to be ineffective.

Zafirlukast side effects

Percentages show how often each reaction appears relative to total reports for zafirlukast.

1
Dyspnoea8.1%204
2
Asthma6.9%174
3
Drug Ineffective4.7%118
4
Fatigue4.6%116
5
Dyspnoea4.5%114
6
Asthma4.4%110
7
Nausea3.7%94
8
Malaise3.6%91
9
Headache3.6%90
10
Cough3.4%87
11
Off Label Use3.4%85
12
Drug Ineffective3.2%80
13
Pneumonia3.1%79
14
Pain3.1%79
15
Dizziness2.8%71

These are voluntary reports and do not establish that zafirlukast caused these reactions.

Report severity

56.2%Serious1,419 reports
25.3%Hospitalizations639 reports
5.7%Fatal145 reports

Seriousness is determined by the reporter, not by OpenClaim.

Zafirlukast drug interactions

Other drugs that appear in adverse event reports alongside zafirlukast. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Omalizumab6.6%167
2
Fluticasone6.6%166
3
Dupilumab6.6%166
4
Budesonide6.2%157
5
Salmeterol-xinafoate5.8%146
6
Formoterol4.1%103
7
Esomeprazole3.9%99
8
Tiotropium-bromide3.2%82
9
Sodium-oxybate3.2%81
10
Albuterol3.0%76
11
Omeprazole2.7%67
12
Montelukast-sodium2.4%60
13
Adalimumab2.2%56
14
Prednisone2.2%56
15
Mepolizumab1.5%38

Taken alongside

1
Albuterol38.9%981
2
Fluticasone30.4%768
3
Salmeterol-xinafoate18.6%470
4
Acetaminophen17.5%441
5
Prednisone16.3%411
6
Levothyroxine-sodium15.6%395
7
Ergocalciferol14.8%374
8
Budesonide13.9%352
9
Aspirin12.8%323
10
Omeprazole12.6%319
11
Furosemide12.4%312
12
Ipratropium-bromide11.2%282
13
Formoterol11.0%277
14
Cetirizine-hydrochloride10.5%266
15
Atorvastatin-calcium10.3%259

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports zafirlukast side effects

71.1% of zafirlukast adverse event reports involve female patients and 23.0% involve male patients. The largest age group is adult at 63%. These figures reflect who reports side effects, not underlying risk.

Sex

Female71.1%
Male23.0%
Unknown5.9%

Age group

< 2<0.1%
2–110.5%
12–171.2%
18–6463.2%
65+35.0%

What is zafirlukast used for

Conditions and purposes for which patients were taking zafirlukast when the adverse event was reported.

Analgesic Asthma SyndromeAsthmaAsthma ProphylaxisAsthmaBlood Cholesterol IncreasedBlood Pressure AbnormalBlood Pressure MeasurementBreast OperationBreast ReconstructionBronchial DisorderBronchiectasisBronchiolitisBronchitisBronchopulmonary Aspergillosis AllergicBronchopulmonary Aspergillosis Allergic

Showing 15 of 76 indications

Zafirlukast brand names and reporting trend

Zafirlukast is sold under the brand name Zafirlukast.

Brand names

Zafirlukast916

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking zafirlukast with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.