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