Levocetirizine + Montelukast is a combination of two medicines: Levocetirizine and Montelukast, which relieves sneezing and runny nose due to allergies. Levocetirizine is an antiallergic which blocks a chemical messenger (histamine) responsible for runny nose, watery eyes and sneezing. Montelukast is a leukotriene antagonist. It works by blocking another chemical messenger (leukotriene). This reduces inflammation (swelling) in the airways and nose, and improves symptoms.