What is the risk of psychiatric issues associated with Singulair (montelukast)?

Risk of Psychiatric Issues with Singulair (Montelukast)

Singulair (montelukast) carries a significant risk of serious neuropsychiatric adverse events, prompting the FDA to issue a boxed warning in 2020, and should be reserved for patients with inadequate response or intolerance to alternative therapies, particularly when symptoms are mild. 1

FDA Boxed Warning and Regulatory Position

The FDA drug label explicitly warns about serious neuropsychiatric events including agitation, aggressive behavior, hostility, anxiousness, depression, disorientation, hallucinations, insomnia, irritability, memory impairment, obsessive-compulsive symptoms, restlessness, sleepwalking, suicidal thoughts and behavior (including completed suicide), tics, and tremor 1. These events have occurred in patients both with and without prior psychiatric history, and importantly, some symptoms have persisted even after discontinuing the medication 1.

The 2024 American Thoracic Society guideline reinforces this concern, noting that the FDA strengthened warnings about serious behavior and mood-related changes, including suicidal thoughts or actions, and recommended that montelukast's benefits may not outweigh risks when disease symptoms are mild and treatable with alternatives 2.

Quantifying the Risk: Recent Evidence

Observational Studies Show Mixed but Concerning Signals

The most recent 2025 Swedish nationwide cohort study of 74,291 children (ages 6-17) found no increased overall risk of neuropsychiatric adverse events when comparing montelukast to long-acting beta-agonists (HR 0.99,95% CI 0.84-1.16) 3. However, this contrasts sharply with other high-quality evidence.

A 2023 Danish nationwide cohort study of adults with asthma demonstrated that montelukast initiation was significantly associated with:

• 14% increased risk of requiring neuropsychiatric medication (HR 1.14,95% CI 1.08-1.20) 4
• Age-stratified risk showing highest vulnerability in younger adults (ages 18-29: HR 1.28; ages 30-44: HR 1.16) 4

A 2022 propensity-matched cohort study of 154,946 patients found:

• 11% increased odds of any neuropsychiatric outcome in asthma patients (OR 1.11,95% CI 1.04-1.19) 5
• 7% increased odds in allergic rhinitis patients (OR 1.07,95% CI 1.01-1.14) 5
• Highest risk for anxiety disorders (OR 1.21 in asthma) and insomnia (OR 1.15 in allergic rhinitis) 5

A 2026 cross-sectional study from Saudi Arabia found montelukast users had:

• 4.1-fold increased odds of anxiety symptoms (aOR 4.1,95% CI 2.01-8.45) 6
• 4.3-fold increased odds of depressive symptoms (aOR 4.3,95% CI 1.92-9.86) 6

A 2025 meta-analysis confirmed 11% increased risk of anxiety (RR 1.11,95% CI 1.06-1.16) without heterogeneity between studies 7.

Clinical Algorithm for Prescribing Decisions

When to AVOID Montelukast:

• Allergic rhinitis with mild symptoms adequately controlled by intranasal corticosteroids or antihistamines 1
• Any patient with current or prior history of depression, anxiety, suicidal ideation, or other psychiatric disorders
• Children and young adults (highest risk group per age-stratified data) 4
• Patients with sleep disorders or insomnia

When Montelukast May Be Considered (After Risk-Benefit Discussion):

• Asthma patients unable or unwilling to use inhaled corticosteroids 8
• Combined asthma and allergic rhinitis requiring unified treatment 9
• Aspirin-exacerbated respiratory disease 1
• Exercise-induced bronchoconstriction as adjunct 1
• Documented intolerance to or failure of preferred therapies

Mandatory Monitoring Protocol:

1. Pre-treatment counseling: Explicitly discuss neuropsychiatric risks with patients and caregivers 1
2. Baseline assessment: Document current mental health status, sleep patterns, behavioral characteristics
3. Early monitoring: Weekly contact during first month (highest risk period for symptom emergence)
4. Ongoing surveillance: Monthly assessment for behavioral changes, mood alterations, sleep disturbances
5. Immediate discontinuation protocol: If ANY new neuropsychiatric symptoms emerge, stop montelukast immediately and contact healthcare provider 1
6. Post-discontinuation monitoring: Continue supportive care until symptoms resolve, as some cases show persistent symptoms 1

Comparative Efficacy Context

Montelukast is consistently less effective than inhaled corticosteroids for asthma 8 and less effective than intranasal corticosteroids for allergic rhinitis 9. The 2020 NAEPP guidelines note that montelukast and other leukotriene receptor antagonists have "increased risk of adverse consequences" that make their use "less desirable," explicitly referencing the FDA boxed warning 10.

Critical Pitfalls to Avoid

1. Do not minimize the boxed warning: This is the FDA's strongest safety alert short of withdrawal
2. Do not assume prior tolerance predicts future safety: Neuropsychiatric events can occur at any time during treatment
3. Do not continue montelukast if behavioral changes occur: The risk of persistent symptoms after discontinuation mandates immediate cessation 1
4. Do not use as first-line for mild disease: Reserve for inadequate response to safer alternatives 1
5. Do not overlook age-related vulnerability: Younger patients show disproportionately higher risk 4

Mechanism and Biological Plausibility

Animal studies demonstrate that montelukast distributes into the brain in rats 1, providing biological plausibility for central nervous system effects, though the exact mechanisms remain poorly understood 1.