Lip stain is a cosmetic product used to color the lips, usually in liquid or gel form. It generally lasts longer than lipstick and leaves less color on the lips. A lip stain is a lip product in which the skin absorbs the color, rather than creating a layer on the lips like lipstick. While it doesn't have the resistance of a commercial lip shade, you know it's perfectly safe. Just be sure to use a lip brush and not your finger when applying it to keep germs out. Also, keep the stain in the refrigerator to prolong its freshness.