Difficulty breathing and coughing up phlegm are two symptoms of asthma, says the American Lung Association. However, those are also symptoms of bronchitis and pneumonia, notes Healthline. Chronic obstructive pulmonary disease, or COPD, is also characterized by problems with breathing and phlegm.
In general, asthma is characterized by additional mucus and narrowed, inflamed breathing passages, according to Mayo Clinic. Other symptoms include chest pain or tightness, wheezing, disrupted sleep and shortness of breath. The severity of asthma differs significantly among patients. Some have symptoms continually, while others experience them in specific situations, such as during exercise or exposure to allergens.