|A cough that is accompanied with mucus or phlegm (sputum), commonly called a "productive cough," is usually a sign that an infection has developed in the lungs. Coughing up phlegm or mucus can be caused by various things and include the common cold, allergies, irritants (smoking, dust, pet dander, chemical fumes), gastro-esophageal reflux or bacterial or viral infections in the lungs such as acute bronchitis, pneumonia, whooping cough, croup in children. The mucus or phlegm often varies in consistency and color ranging from yellow, green, brown, grey or may even contain blood.
Coughing mucus and phlegm commonly occurs in the morning. If you are coughing up mucus and phlegm and it persists, consult your doctor. Constantly coughing mucus and phlegm can lead to nausea. Based on your cough symptoms, your doctor will perform a physical examination as well as certain diagnostic tests. Tests such as a chest x-ray, blood tests, sputum examination, ECG and CT exam may be ordered to rule out serious diseases such as TB or lung cancer.