As per Clinical Therapeutics, Vol 40, July 2018, A fixed dose combination of Montelukast and Levocetirizine is safe and effective for the treatment of Perennial Allergic Rhinitis and Asthma compared to Montelukast alone. Levocetirizine reduces the Vascular permeability and inhibits release of Histamine into airway. Montelukast is a leukotriene receptor Antagonist and reduces Bronchoconstriction. Cozytril LM tablet is used for Allergic Bronchial Asthma, Allergic Rhinitis, Persistent Allergic Rhinitis, Seasonal Allergic Rhinitis, Perennial Allergic Rhinitis and Idiopathic Urticaria.