What are inhaled corticosteroids and why are they first-line controllers for asthma?

Inhaled corticosteroids, or ICS, like fluticasone, budesonide, and beclomethasone are the most effective long-term controller medications for persistent asthma. They reduce airway inflammation, mucus production, and bronchial hyperresponsiveness. ICS are first-line because they reduce asthma exacerbations, hospitalizations, and deaths more effectively than any other single controller medication. They are taken daily regardless of symptoms. Local side effects include oral thrush from candida overgrowth and dysphonia or hoarseness. Rinsing the mouth after each use prevents thrush.