Answer

For anyone coughing up yellow phlegm, it is often a sign of bronchial infection, but minor diagnoses are often created from the color of the phlegm. If you are coughing up yellow, green, or brown phlegm, the body is in the process of fighting some sort of infection.

If the color of your phlegm is brown or gray, it could be the body is expelling tars or resins accumulated from smoking or inhaling too much of dust.

Causes of coughing up yellow phlegm

Coughing up yellow phlegm can be due to various causes which are as follows:

Common cold, a frequent cause of acute coughing up phlegm in the morning and phlegm in throat.

Allergies due to irritants, like, dust, pet dander, chemical fumes, etc.

Smoking, causing coughing up phlegm that is green rusty brown yellow blood-stained or foul smelling.

Gastro-esophageal reflux or bacterial or viral infections in the lungs, like, acute bronchitis, whooping cough, croup in children.

Severe illnesses, like, pneumonia, asthma, acute heart failure or pulmonary embolism (a clot in the blood vessels of the lung) may lead to coughing up phlegm for 3 weeks.

Related Resources:

1. Coughing Up Yellow Mucus