If pneumonia is not treated effectively, it can lead to serious complications that significantly impact long-term health. Sepsis is a life-threatening condition where the infection spreads into the bloodstream, causing a body-wide inflammatory response that can lead to organ failure and lasting damage to the heart, kidneys, or brain. Pleural effusion occurs when fluid builds up in the space between the lungs and the chest wall; if infected (empyema), it can cause persistent fever, scarring, and permanent lung compression, requiring surgical drainage. A lung abscess is a pus-filled cavity in the lung tissue that can cause prolonged illness, coughing up blood, and chronic scarring, which may permanently reduce lung function and cause breathlessness long after the infection clears. These complications underscore the critical need for prompt and complete treatment of pneumonia.