Green phlegm indicates a widespread and robust immune response. The white blood cells, germs, and other cells and proteins produced during the immune response are what give the phlegm its green color. While phlegm of this color can point to an infection, antibiotics are not always needed.

What bacteria causes green sputum?

Streptococcus pneumoniae: Rust-colored sputum. Pseudomonas, Haemophilus, and pneumococcal species: May produce green sputum.

Does Covid cause green phlegm?

While both can cause coughing, coronavirus causes a dry cough and can often leave you breathless. The common chest cold will cause a yellow or green phlegmy cough. If you have a common chest cold, your symptoms are more likely to be mild and stay mild.