Red 6 Good Colouring Agent/Pigment No known benefits Red 6 at a glance Pigment used to add colour to makeup and skin care Ruled safe in its current use Also known as D&C Red No. 6 Red 6 description Red 6 is a synthetic pigment used to add colour to makeup, as well as skin care products. It is water soluble. The United States Food and Drug Administration has ruled Red 6 safe in its current use. It is also known as D&C Red No. 6, indicating it is approved for use in drugs and cosmetics, but not in foods.