Should Cetirizine Be Stopped After Starting Montelukast?
No, cetirizine should not be stopped after starting montelukast—these medications work through different mechanisms and can be safely continued together, with combination therapy often providing superior symptom control compared to either agent alone. 1, 2, 3
Rationale for Continuing Both Medications
Complementary Mechanisms of Action
- Cetirizine blocks histamine receptors to reduce sneezing, rhinorrhea, and itching, while montelukast blocks leukotriene receptors to primarily address nasal congestion and inflammation 1, 4
- These distinct pathways target different inflammatory mediators in allergic disease, making combination therapy mechanistically rational 3, 4
Evidence Supporting Combination Therapy
- Combination therapy with montelukast plus antihistamines (cetirizine or desloratadine) produces significantly greater improvement in nasal symptoms than either medication alone in patients with persistent allergic rhinitis 3
- A randomized controlled trial demonstrated that montelukast-levocetirizine combination achieved mean nasal symptom scores of 2.14 compared to 3.02 with levocetirizine alone and 3.44 with montelukast alone 3
- Gradual symptom improvement continues over 6 weeks with combination therapy, with the greatest benefit seen when both agents are used together 2
Safety Profile of Concurrent Use
- No contraindications or drug interactions exist between montelukast and cetirizine 1
- Both medications can be taken without regard to timing relative to each other, though montelukast is typically recommended in the evening 1
- No dose adjustments are required when using these medications concurrently in patients with normal liver and kidney function 1
Clinical Context and Caveats
When Montelukast Alone May Be Considered
The EPOS 2020 guidelines note that montelukast has very low quality evidence for chronic rhinosinusitis and is not recommended unless patients cannot tolerate nasal corticosteroids 5
Important Safety Monitoring
- The FDA has issued a black box warning regarding potential mood changes, depression, and suicidal thoughts with montelukast 1
- Patients should be monitored for unusual behavioral or mood changes when starting or continuing montelukast therapy 1
- Various neuropsychiatric events have been reported with anti-leukotrienes, though evidence of association remains conflicting 5, 6
Onset of Action Differences
- Cetirizine provides symptom relief within hours of administration 1
- Montelukast begins producing clinical benefits within 1-2 days, providing continuous control rather than acute symptom relief 1, 7
- Both medications demonstrated significant improvement within the first 24 hours in controlled trials 2
Practical Recommendation
Continue both medications together unless there are specific contraindications, intolerance, or inadequate response. The combination provides complementary mechanisms targeting different aspects of allergic inflammation, with established safety and superior efficacy compared to monotherapy 1, 2, 3, 4