Can Montelukast Cause Drowsiness?
Yes, montelukast can cause drowsiness, though this is not one of its most common side effects. The FDA drug label explicitly lists drowsiness as a reported adverse reaction, and multiple clinical guidelines acknowledge this potential effect 1.
Evidence from FDA Drug Labeling
The official FDA prescribing information for montelukast (Singulair) clearly identifies drowsiness as a possible side effect 1. In post-marketing surveillance and clinical studies, drowsiness has been documented among the adverse reactions, though it occurs less frequently than other neuropsychiatric effects 1. The FDA label also notes that "the incidence of somnolence was similar to that of placebo" in controlled clinical trials for allergic rhinitis, suggesting the drowsiness rate is relatively low 1.
Clinical Guideline Perspectives
The 2019 Journal of Allergy and Clinical Immunology guidelines on mast cell activation syndrome note that while montelukast itself is not specifically characterized as sedating, it is mentioned in the context of medications that may affect alertness 2. This guideline contrasts montelukast with clearly sedating antihistamines (like diphenhydramine) and other agents known to cause drowsiness 2.
The 2018 ESMO delirium guidelines list multiple sedating medications but do not specifically categorize montelukast among the primary sedating agents, suggesting drowsiness is not a predominant concern compared to antihistamines or benzodiazepines 2.
Research Evidence on Sleep-Related Effects
Recent research reveals a more complex picture regarding montelukast and sleep disturbances:
A 2022 pediatric study found sleep disturbance was the most common adverse reaction to montelukast, affecting 15.1% of children, including sleep difficulties (5.5%), sleep interruption and decreased sleep (4.4%), and nightmares (1.82%) 3.
A 2025 cross-sectional analysis of NHANES data (2005-2018) involving 16,520 adults found that montelukast exposure was associated with sleep disorders (OR: 1.72; 95% CI: 1.32-2.26) after adjusting for multiple confounding factors 4.
A 2014 systematic review of case reports identified sleep disturbance as one of the documented adverse drug reactions to montelukast, along with other neuropsychiatric effects 5.
Important Clinical Context
The FDA issued a black box warning in 2020 regarding serious behavior and mood-related changes with montelukast, which includes sleep-related disturbances 2. The 2024 American Thoracic Society guidelines specifically reference this warning when discussing montelukast use in children with persistent obstructive sleep apnea 2.
Practical Considerations
- Drowsiness from montelukast appears less predictable and less common than with traditional sedating antihistamines 2.
- Sleep disturbances (including both insomnia and excessive sleepiness) may occur more frequently in children than adults 3, 6.
- The mechanism may involve multiple pathways including estrogen signaling and receptor activation pathways, rather than direct sedation 4.
- Symptoms typically appear within days to months of starting treatment and resolve after discontinuation 6.
Monitoring Recommendations
Patients and caregivers should be counseled to monitor for drowsiness, sleep disturbances, and other neuropsychiatric changes when initiating montelukast 1, 3. If drowsiness or sleep problems develop and are clinically significant, discontinuation should be considered, particularly given alternative treatment options for asthma and allergic rhinitis 2, 3.