What causes yellow phlegm in the lungs?

Yellow phlegm in the lungs may be caused by upper respiratory tract infections, bronchitis, pneumonia, or other conditions.

1. Upper Respiratory Tract Infection

This condition is a general term for acute inflammation of the pharynx, larynx, and nasal passages. It is primarily caused by infection with pathogens such as viruses or bacteria. Two to three days after onset, yellow phlegm may appear in the lungs, accompanied by symptoms such as hoarseness, sore throat, reduced sense of taste, and body aches.

2. Bronchitis

When the body is affected by infectious or non-infectious factors, chronic nonspecific inflammation may develop in the trachea, bronchial mucosa, and surrounding tissues. After onset, yellow phlegm may occur along with symptoms such as coughing, wheezing, and shortness of breath.

3. Pneumonia

When the lungs are infected by pathogens such as viruses or bacteria, infectious inflammation may develop in the alveoli, distal airways, and lung interstitium. Under inflammatory stimulation, yellow phlegm may appear in the lungs, accompanied by symptoms such as coughing and fever.

In addition to the above, yellow phlegm could also result from conditions such as lung abscess or tuberculosis. It is recommended to maintain a light diet, drink plenty of water appropriately, and ensure adequate hydration in the body.