Asthma is a condition in which your airways narrow and swell and may produce extra mucus. This can make breathing difficult and trigger coughing, a whistling sound when you breathe out, and shortness of breath. For some people, asthma is a minor nuisance.
What is the main cause of asthma?
The most common asthma triggers include allergies, air pollution, and other airborne irritants, other health conditions including respiratory infections, exercise or physical activity, weather and air temperature, strong emotions, and some medicines.