Mucus is a vital, slippery substance lining your body’s passages (nose, lungs, gut, etc.) that moisturizes tissues and traps germs, dust, and irritants, acting as a key part of your immune defence, often noticeable as snot or phlegm when you’re sick and producing more to flush out invaders like viruses. While normally clear and thin, changes in its colour, thickness, or amount (becoming thick, coloured, or excessive) signal your body fighting an infection, requiring you to stay hydrated, use saline sprays, or seek medical advice if severe.
