The combination of Montelukast Sodium (equivalent to Montelukast 4mg) and Levocetirizine Dihydrochloride 2.5mg is commonly used to manage allergic conditions and respiratory issues. Montelukast is a leukotriene receptor antagonist that works by blocking leukotrienes, substances in the body that cause inflammation, bronchoconstriction, and mucus production, helping to prevent asthma attacks and reduce allergy symptoms like nasal congestion. Levocetirizine is an antihistamine that works by blocking histamine receptors, which helps alleviate symptoms of allergic rhinitis, such as sneezing, runny nose, and itchy eyes. This combination is effective in treating conditions like seasonal allergies, allergic rhinitis, and asthma, providing relief from both allergic symptoms and inflammation in the airways.