Pharmacologic class (EPC) · 3 drug pages

Leukotriene receptor antagonist: adverse event reports filed with FDA

38,515 reports list a drug in this class as a suspect or interacting product, 2004–2026.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "There is no certainty that the reported event (adverse event or medication error) was actually due to the product. FDA does not require that a causal relationship between a product and event be proven, and reports do not always contain enough detail to properly evaluate an event." The information in these reports "cannot be used to estimate the incidence of these events."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

38,515
reports across the class: 0.2% of all reports; 2,088
reports, 12 months to June 2026: 2,677 in the 12 months before; 86.6%
marked serious by the reporter: 57.4% across all reports; 3
drugs with a page: brand and generic names counted separately

Leukotriene receptor antagonist is a pharmacologic class (an FDA Established Pharmacologic Class) with 3 drug pages on this site. Together those drugs are listed as a suspect or interacting product in 38,515 adverse event reports received by FDA, 0.2% of the database, from January 2004 to June 2026.

2,088 reports arrived in the 12 months to June 2026, down 22% from 2,677 in the 12 months before. FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases. 86.6% of the class's reports are marked serious, 4.1% record death among the outcomes and 27.9% record hospitalisation, as reported.

Across the class the reactions recorded most often are asthma (27.5%), dyspnoea (20.3%) and wheezing (16.5%). The class median share shown beside each term is the middle value across the member drugs; it is the comparison used on every drug page in this class.

The members table is ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Drugs in the class

Drug	Name type	Reports	Latest 12 months	Marked serious	Top term recorded
SingulairMontelukast sodium	brand	18,951	488	83.4%	Asthma
Montelukast	generic	12,863	1,066	89.8%	Asthma
Montelukast sodium	generic	6,701	534	89.5%	Asthma

Ordered by report count for navigation only. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic."

Reports by month, five years

FDA releases FAERS data quarterly, so the newest months are incomplete and grow in later releases.

Reactions recorded across the class

share of class reports recording the termmedian drug in the class

Asthmaasthma27.5%10,589
Dyspnoeashortness of breath20.3%7,829
Wheezingwheezing16.5%6,339
Drug ineffectivethe medicine did not work as expected11.6%4,485
Coughcough11.4%4,373
Therapeutic product effect incomplete10.1%3,894
Anxietyanxiety10%3,834
Loss of personal independence in daily activities8%3,075
Depressionlow mood7.9%3,027
Headachehead pain7.6%2,935
Pneumonialung infection7.4%2,844
Fatiguetiredness6.8%2,627
Drug hypersensitivityan allergic-type reaction to a medicine6.6%2,547
Obstructive airways disorder6.6%2,535
Sleep disorder due to a general medical condition6.3%2,408
Painpain, site not specified6.2%2,384
Suicidal ideationthoughts of suicide6%2,320
Aggressionaggressive behaviour5.5%2,118
Insomniadifficulty sleeping5.3%2,043
Malaisegeneral feeling of being unwell5.2%2,008
Chest discomfortchest discomfort5.2%2,007
Full blood count abnormal5%1,930
Vomitingbeing sick5%1,910
Hypertensionhigh blood pressure4.9%1,902
Pyrexiafever4.8%1,864

Solid bar: share of all class reports. Hollow bar: the median share across the 3 member drugs, the reference used on each member's page. One report can record several terms.

Outcomes, patients and reporters

Outcomes recorded

Death4.1%1,579

Life-threatening6.2%2,392

Hospitalisation (initial or prolonged)27.9%10,727

Disability7.6%2,935

Congenital anomaly0.9%331

Other serious67.5%25,999

Not serious13.4%5,169

Patient age

Under 21.3%500

2 to 1113.9%5,352

12 to 174.1%1,582

18 to 4415.1%5,809

45 to 6421.4%8,248

65 to 7410.1%3,898

75 and over6.6%2,528

Age not given27.5%10,598

Who reported

Physician24.1%9,297

Pharmacist4.1%1,564

Other health professional29.2%11,246

Lawyer1%371

Consumer or non-health professional38.1%14,682

Not given3.5%1,355

Grey bar: all 20,646,523 reports in the database. Outcome flags are as the reporter set them and are not verified by FDA.

Questions about Leukotriene receptor antagonist reports

Which drugs are in the Leukotriene receptor antagonist class on this site?

Singulair, Montelukast and Montelukast sodium. Class membership comes from the pharmacologic class (EPC) on the drug's FDA label.

How many reports does the class have?

38,515 reports through June 2026, 2,088 of them in the latest 12 months. A report listing two drugs of the class counts once for each.

What reactions are recorded most often?

asthma (27.5%), dyspnoea (20.3%), wheezing (16.5%), drug ineffective (11.6%) and cough (11.4%).

Can the members table be used to rank the drugs?

No. FDA states that adverse event reports "represent a small percentage of total usage numbers of a product", that "common products may have a higher number of adverse events due to the higher total number of people using the product", and that the data "by themselves are not an indicator of the safety profile of the drug or biologic." Drugs differ in how many people take them, in the conditions they treat, in time on the market and in how diligently reports are collected.

How do I report an adverse event?

Through FDA MedWatch (Form FDA 3500, or 1-800-FDA-1088) or to the manufacturer. See the guide on how to report.

Where this comes from. Counts are built from the openFDA Drug Adverse Event (FAERS) bulk export released 28 Sep 2026, which holds reports FDA received through 30 Jun 2026. Drug names are as reported, resolved to the brand or generic name on the FDA label where openFDA's harmonisation matched them; classes are the pharmacologic class (EPC) from the label and the National Drug Code Directory of 17 Sep 2026. A class is the Established Pharmacologic Class most often attached to a drug's reports by openFDA's label harmonisation, or from the NDC Directory where reports carry none. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.