Coughing and phlegm may be caused by respiratory infections or pneumonia. Respiratory infections are usually infections that occur in the nasal cavity and throat area. Coughing, sneezing, and increased sputum occur when there is an increase in glandular secretions that clear and adhere to harmful substances such as bacteria, foreign bodies, and viruses when infections occur in these two areas. Coughing is a normal bodily reaction that helps the body clear the respiratory tract and lungs of bacteria, viruses, and foreign bodies. The presence of coughing sputum when coughing indicates that harmful substances are being expelled from the body, and the patient may also experience flu-like symptoms such as mild fever, nasal congestion, and a runny nose. Pneumonia causes the air sacs of the lungs, or alveoli, to become infected, and the alveoli are filled with fluid or pus, causing the body to respond with a cough, along with fever, difficulty breathing, shortness of breath, lack of energy, and other symptoms. The exact cause of coughing and phlegm can only be determined after further examination.