Fast-acting drugs inhaled into the lungs can quickly and directly reach and act on the diseased area, which can play a rapid role in dilating the bronchial tubes and fighting airway inflammation. Unlike oral medications, inhalation medications need to be absorbed into the bloodstream through the gastrointestinal tract and then reach the lungs. For example, after inhalation of beta 2 agonist, 5-10 minutes to take effect. Portable quantitative inhalers are small and lightweight, and can be carried around without special equipment, making inhalation convenient and widely used around the world. The inhalation dosage is often only 1/10 to 1/20 of the oral dosage. Less side effects The inhaled drug is not absorbed by the digestive tract and metabolized by the liver, and can be applied to the airway mucosa, thus reducing the adverse effects caused by oral and intravenous administration.