Symptoms of asthma and bronchitis may overlap.
George Doyle/Stockbyte/Getty Images
Your lungs and airways are susceptible to a variety of diseases, including those caused by infectious organisms, environmental agents, genetic abnormalities and immune disorders. Bronchitis -- a nonspecific term for inflammation of your medium-sized airways -- can be caused by infections or exposure to environmental irritants. Asthma is a lung disorder characterized by airway inflammation, partially reversible airflow obstruction and hyper-reactivity to various stimuli, such as pollens, dust or smoke. While bronchitis and asthma share certain features and may coexist, they are different conditions.
Inflammation: A Universal Response
Your airways respond to irritation in a predictable fashion. Whether the initial insult is an infectious agent, pollen, smoke or an occupational aerosol, airway irritation triggers the release of inflammatory chemicals from immune cells embedded within your lungs' mucus membranes. These chemicals exert widespread effects that include increased mucus production and blood flow, thickening of your airway walls and stimulation of cough reflexes. If you have asthma, the muscles surrounding your airways may constrict, leading to reduced airflow.
Symptoms May Overlap
Bronchitis can be classified as acute or chronic. Acute bronchitis is usually the result of a viral infection, while the most common cause of chronic bronchitis is smoking. In either acute or chronic bronchitis, the most notable symptom is cough. The hallmark of asthma is wheezing, which is a high-pitched whistling sound heard during exhalation. However, the presence or absence of cough or wheezing will not necessarily distinguish bronchitis from asthma. Wheezing may be heard during bouts of acute bronchitis in people who do not have asthma, and asthma is one of the most common causes of a cough. Furthermore, people with asthma do not always wheeze. Thus, it may be difficult to distinguish bronchitis from asthma in certain situations. Your doctor may order further evaluation, such as spirometry or pulmonary function tests, to clarify your diagnosis.
Does Bronchitis Trigger Asthma?
If you already have asthma, an episode of acute viral bronchitis can aggravate your condition. In fact, viral respiratory infections are among the most common causes of hospitalization for people with asthma. Some evidence suggests that viral respiratory infections in children -- particularly infections caused by rhinoviruses or respiratory syncytial virus -- may increase the risk for asthma later in life. However, the most common trigger for asthma is sensitivity to environmental allergens, such as pollens or dust mites.
Management May Overlap
Asthma and chronic bronchitis both require long-term therapy. Many of the medications used by people with asthma -- antiinflammatory and airway-expanding inhalers -- are also used by people who have chronic bronchitis. When people with asthma or chronic bronchitis suddenly get worse, doctors may prescribe antibiotics, as well. In contrast, acute bronchitis typically only lasts 2 to 3 weeks, and inhalers are not necessary unless you are wheezing. Antibiotics are usually not required. Due to the difficulty in differentiating between bronchitis and asthma, people who have persistent coughing or wheezing should see a medical professional.