When you're sick you'll often produce more phlegm, and might notice it's thicker or a different color: white, green, yellow or maybe even brown. We all produce mucus, even when healthy. Mucus is a ...

Clear, bubbly phlegm does not typically indicate a problem. However, coughing up large amounts could indicate an underlying health issue, such as fluid in the lungs. Phlegm, or sputum, is a type of ...

When a person has black or dark-colored mucus, they may have inhaled potentially harmful pollutants. Coughing up black mucus may also be due to an underlying infection or condition. Mucus serves an ...