People are obsessed with the color of their secretions. In the hospital, you often get detailed descriptions about the color changes in a person’s stool, urine, or sputum. Stool color changes can reflect illness, but urine color is rarely helpful unless blood is present. As for snot, identifying the rainbow of possibilities may be helpful in some patients. Green is the only potentially worrisome shade. The green color comes from white blood cells called neutrophils. These immune cells appear when bacteria starts infecting the nasal passages or airways. When the white cells start fighting the infection, they produce an enzyme called myeloperoxidase. Myeloperoxidase is green because it contains a lot of iron.
Now, the hint of a green tinge doesn’t necessarily mean that you need antibiotics. If it is just in your nose at the beginning of an illness, it will probably pass. But if you are coughing it up, have underlying lung disease, or symptoms persist, go see your doctor.
So don’t take umbrage with people who blow their noses and then carefully inspect the tissue or handkerchief to evaluate their production. They are just being vigilant.
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"What turns snot green?" was posted on Wednesday, May 28th, 2008 at 10:20 pm.