The severity of the disease is not usually determined clinically by the color of the sputum, which mostly represents different pathogenic infections. The common pathogens that cough up white sputum are viruses, mycoplasma, tuberculosis, candida infections, etc. The body mobilizes a large number of white blood cells for immunity, which makes the sputum appear white. Common diseases are common cold, chronic bronchitis, bronchial asthma, tuberculosis, lung cancer, etc. Coughing yellow sputum is common in bacterial infections, such as Streptococcus pneumoniae, Streptococcus pyogenes, and Pseudomonas aeruginosa infections, where apoptotic leukocytes mix with pigments produced by bacteria, causing sputum to appear yellow. Common diseases are bacterial pneumonia, lung abscess, bronchiectasis, bacterial acute bronchitis, etc. It should be noted that even for the same disease, the sputum coughed up can appear differently depending on the cause. Take the common cold as an example, patients can cough up both yellow and white sputum. If the common cold is combined with a viral infection or mycoplasma infection, the patient will have a dry cough or a small amount of white sputum. In the case of secondary bacterial infection, the patient may cough yellow sputum. If a patient has coughing symptoms, he or she should go to the respiratory medicine department of the hospital and have the cause clarified by the results of throat swabs, blood tests and other related tests. If the diagnosis is confirmed, patients need to take medication according to the specific cause. In addition, patients should drink more water to speed up the expulsion of phlegm.