This can lead to a sinus infection.
But when less concentrated, the mucus appears pale green—which, depending on how your eyes work, might look yellow to you instead.
Albert Rizzo, the chief medical officer of the American Lung Association, there are many reasons for why someone might be coughing up blood.
However, be on watch for oximeter declines or pulse rate elevation at rest, or return of fever - these can be signs of post-day7-8 hyperinflammation and an early treatment doctor would give steroids-at-day8 to quell this hyperinflammation to prevent progression to hypoxia etc.
What really matters is your accompanying symptoms and how long they stick around, Dr.
Mucus even contains some antibodies to help neutralize germs that can make you sick 1, , M.