Yes, a child can safely take Zyrtec (cetirizine) and Singulair (montelukast) together.
The combination of cetirizine and montelukast is safe and often more effective than either medication alone for treating allergic conditions in children. The FDA-approved dosing for both medications allows concurrent use, and recent high-quality research demonstrates this combination provides superior symptom control with minimal adverse effects 1, 2.
Evidence Supporting Combined Use
FDA Approval and Safety
The Singulair FDA label explicitly states that patients with both asthma and allergic rhinitis should take only one dose of montelukast daily, but does not contraindicate concurrent antihistamine use 1. The label documents that combination therapy is standard practice, with no drug-drug interactions or safety concerns noted between these medication classes.
Clinical Efficacy Data
A 2024 randomized controlled trial in 147 children aged 6-14 years demonstrated that montelukast plus levocetirizine (a cetirizine analog) was significantly more effective than montelukast alone 2. The combination group showed:
- Greater reduction in daytime nasal congestion (p=0.0341)
- Better control of rhinorrhea (p=0.0469)
- Improved nighttime symptoms (p=0.0381)
- Superior quality of life improvements (p<0.0001)
- Fewer adverse events than monotherapy
A 2022 multicenter study of 2,254 patients with allergic rhinitis and asthma confirmed these findings, showing significant symptom improvement with the combination over 3-6 months with no serious adverse reactions 3.
Age-Appropriate Dosing
For children 6-14 years:
- Montelukast: 5 mg chewable tablet once daily
- Cetirizine: Standard pediatric dosing (typically 5-10 mg once daily)
For children 2-5 years:
- Montelukast: 4 mg chewable tablet or oral granules once daily
- Cetirizine: Age-appropriate dosing per product label
Safety Profile
The combination is well-tolerated. Common side effects remain mild and similar to placebo: upper respiratory infections, headache, and pharyngitis 1. Importantly, a 2025 Swedish nationwide study of 74,291 children found no association between montelukast use and neuropsychiatric adverse events (HR 0.99,95% CI 0.84-1.16), contradicting earlier FDA concerns 4.
Clinical Context
While guidelines recommend intranasal corticosteroids as first-line for moderate-to-severe allergic rhinitis 5, the combination of an oral antihistamine and leukotriene receptor antagonist provides a reasonable alternative when:
- Intranasal medications are not tolerated or refused
- Concurrent asthma requires treatment
- Oral therapy is preferred by the family
- Additional symptom control is needed
The combination therapy approach is particularly valuable because it targets different inflammatory pathways—histamine-mediated symptoms via cetirizine and leukotriene-mediated inflammation via montelukast 6.
Administration Timing
Both medications can be given once daily. Montelukast is typically given in the evening for asthma/allergic rhinitis, while cetirizine timing can be individualized. They can be taken together or separately without affecting efficacy 1.