The aftermath of a lung infection such as pneumonia is pleurisy, an inflammation of the pleura, the two-ply membrane that encloses each lung and lines the chest cavity. Pleurisy can also be a complication of tuberculosis or a chest injury.
The layers of the pleura join at edges so that the pleura resemble a balloon, completely empty of air and wrapped tightly around each of the lungs. Normally, only a thin lubricating layer of fluid lies between the inner and outer pleural linings, and the lungs move freely within the pleura during breathing.
If the pleura becomes inflamed by infection, the movement of the lung may be restricted, and breathing, especially deep breathing, will be painful.
Sometimes excess fluid seeps into the pleural space, a condition known as pleural effusion. Although pain may stop because there is no longer any friction between the two layers, pleural effusion is a serious matter that may recur if not promptly attended to. As with pleurisy, it is treated by draining the effusion and treating the underlying condition - the pneumonia or other lung infection that caused the pleural condition.
Many acute respiratory conditions can become chronic, particularly when aggravated by environmental factors such as cigarette smoke or air pollution.