What does it mean when you're coughing up yellow phlegm and then you cough up white phlegm?

The desription of: Phlegm points to infection when yellow, orange or blood tinged, and clear can mean you have cleared a mucus plug. But these are primitive. Allergy, cold and bronchitis can do this, as well as pneumonia...Or cancer. Persistent productive cought needs to be evaluated.

Typical : Phlegm can change from yellow to white. Many times, infection can look dark yellow, dark green, dark brown. If you have drastic worsening of phlegm or even blood, you should definitely see a doctor.