When you’re ill and sometimes hock-up some phlegm, it can be a range of colours from yellowish all the way to brownish. What’s in it that makes it that colour?
In: Biology
Red or brown is blood. Green is dead cells (bacteria, cells killed by viruses, immune cells). Clear phlegm is clean natural mucus without other stuff. Phlegm can also be colored by things you’ve inhaled. I grew up on a farm, and the hay harvest created lots of dust in the barn. When us kids helped with that, our snot was black afterwards.
Brighter red = fresher blood,
Darker red/brown = older blood, vomit from aspiration (inhaling food/vomit), smoke (cigarette, long-term),
Pink & frothy = blood and air (pulmonary oedema – i.e. water in the lungs) is the likely candidate),
Light brown = liquid feed that has been vomited up and the aspirated
Grey/Black = Smoke (fire, cigarette), London underground, other atmospheric pollutants
Yellow/green = Pus, dead microbials (generally bacteria),
Cream = pus
Very light green/clear = more normal sputum, asthma or COPD
Clear & frothy = water (aspiration or pulmonary oedema), normal sputum,
Bright blue = food dye used by the Speech and Language Therapist for swallow tests,
Bright green = my partner forgetting to wear their respirator while painting.
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