These factors include allergies, drugs, pregnancy, molds, cold air, exercise, cigarette smoke, chemical fumes, gastroesophageal reflux, and infections. It is the most common type of asthma, typically first starting in childhood. Seasonal variation in breathing symptoms is common as allergens and environmental factors in the air that cause asthma change. These factors include air temperature and moisture, molds, pollen count, and other air pollutant levels. Drugs, such as aspirin, can precipitate asthma.
Some patients develop asthma during pregnancy.
Asthma attacks are typically episodic. Intervals between attacks can be days, months, or years. In some individuals, asthma can become a daily problem. Symptoms of asthma vary, and are related to the severity of the airway obstruction. Common symptoms include wheezing, coughing, chest tightness, and shortness of breath during attacks.