Salmeterol and Fluticasone Propionate are commonly combined to treat asthma and chronic obstructive pulmonary disease (COPD). Salmeterol is a long-acting bronchodilator that relaxes airway muscles and improves airflow. Fluticasone Propionate is a corticosteroid that reduces inflammation by blocking the release of inflammatory chemicals. Together, they help prevent breathing difficulties, reduce flare-ups, and improve overall respiratory function.