Model released. Young woman using an inhaler to control an asthma attack. Asthma attacks vary in severity from breathlessness, dry cough, wheezing, or a feeling of chest tightness, to chronic breathing difficulty. All symptoms are caused by narrowing of the bronchioles in the lungs and triggered by a variety of stimuli including infection, exertion, emotional stress, and allergens such as pollen and dust. Once an attack has started, a bronchodilator drug (such as salbutamol or terbutaline) is administered; as the patient inhales through the device, the drug is taken up and passed into the bronchi. Relief is usually rapid.