Pneumonia is a lung infection that can range from mild to life threatening. This is usually caused by bacterial or viral infections, but can sometimes be caused by fungal infections or by inhaling (inhaling) the substance into the lungs. Pneumonia causes the airways to swell and the alveoli (alveoli) to fill with fluid. In some cases, the problem occurs in one lobe (segment) of a lung, while severe cases can affect all five lobes.
Treatment may include prescription or over-the-counter medications and respiratory procedures. In severe cases, hospitalization may be necessary.