ASTHMA - A disease process that is characterized by paradoxical narrowing of the bronchi (lung passageways) making breathing difficult. Treatment includes bronchodilators, which are given orally or delivered as an aerosol (inhaled). Corticosteroids are reserved for more difficult cases. Symptoms include wheezing, difficulty breathing (particularly exhaling air), and tightness in the chest. Factors, which can exacerbate asthma, include rapid changes in temperature or humidity, allergies, upper respiratory infections, exercise, stress, or smoke (cigarette). See status asthmaticus.