Phlegm
Green Phlegm: What It Means, 9 Causes & How to Treat
Green phlegm can be caused by bacterial infections, like sinusitis, pneumonia or severe COVID-19 infection. It may also be an immune system response to inflammation, and is often accompanied by symptoms like shortness of breath and a productive cough. Learn more about the causes of green phlegm and when to see a doct.