Pneumonia is an acute respiratory infection that causes inflammation and consolidation of the lungs. It is the second leading cause of death in children under five years old. Pneumonia can be caused by bacteria, viruses, fungi or other pathogens. It is classified based on location in the lungs or cause. Symptoms include fever, cough, difficulty breathing and chest pain. Diagnosis involves physical exam, blood tests, chest imaging and sputum culture. Treatment is with antibiotics and antipyretics. Vaccines can help prevent pneumonia caused by some bacteria. Complications may include pleural effusion or lung damage if not treated properly.