Asthma is a condition of chronic inflammation of the lungs. Pneumonia is an infection of the lungs' tissues, most commonly caused by viruses and bacteria. Both illnesses can present with similar symptoms, including cough, respiratory distress and hypoxia (low oxygen content in the blood).
Asthma does not cause pneumonia, but it can predispose a patient to pneumonia. This happens because asthma weakens the lungs' ability to clear up mucous and other cellular debris, weakening the lung's protective mechanisms against microbes.
Likewise, pneumonia can trigger an asthma attack. The body's response to microbial infections in the lungs involves attracting white blood cells and releasing proteins involved in the generation of inflammation that kills the microbes. Some of these substances can also trigger the inflammation of asthma.
X-rays can help in the diagnosis of pneumonia, but the findings in patients with asthma can resemble the findings of patients with pneumonia. These include nonspecific infiltrates, which can be signs of inflammation of asthma, or foci of infection in pneumonia.
By controlling asthma, a patient can avoid becoming vulnerable to infections that can result in pneumonia. Likewise, early treatment of pneumonia in patients with asthma can reduce the chance of an asthma exacerbation. Vaccines to prevent pneumonia, including the flu vaccine, are important in the health maintenance of patients with asthma.
Frequent asthma exacerbation and pneumonia can lead to pathological weakening of the lungs, which can lead to infections with more virulent organisms, increasing the possibility of hospitalization and long-term complications.