The prognosis for different degrees of lung infections varies. Patients with mild lung infections may resolve on their own and are not life-threatening. Severe pneumonia, on the other hand, may be fatal within days to weeks if not treated promptly. The prognosis of patients with pulmonary infections is related to the patient’s underlying condition, the type of pathogenic bacteria, and whether timely and effective treatment is given. Patients with mild infections and symptoms can eventually be cured by their own resistance and are not life-threatening, even if they are not treated. However, patients with severe pneumonia need to be actively hospitalized for treatment of the cause and symptomatic management. If a patient with severe pneumonia is not treated effectively and promptly, he or she may suffer a short period of exacerbation and complications, and death may occur within a few days or even a few weeks. Therefore, patients with pulmonary infections are advised to go to the hospital in a timely manner for symptomatic treatment and effective antibacterial therapy to avoid life-threatening progression of the disease, and to eat a light diet and avoid smoking and alcohol as much as possible.