What a 2/5 rating means
On the comedogenic scale, a 2 is still within the non-comedogenic range that dermatologists generally consider low-risk. That places D&C Red #19 in the range most people, including many with acne-prone skin, tolerate well.
One thing the number cannot tell you is concentration. Ingredients are listed in descending order, so D&C Red #19 near the end of a label is present in tiny amounts and matters far less than the same ingredient near the top.
About D&C Red #19
It is a cosmetic colorant that gives makeup its shade. A synthetic xanthene dye used in blushes and lip colour. At 2 it rates lower than the D&C reds most often blamed for cosmetic acne — 17, 21, 3, 30 and 36 — but it is still a pigment worth checking if blush or lipstick breaks you out.
On a label it can read as D&C Red 19, D&C Red #19, D C Red 19, Ci 45170 — worth knowing when you scan an ingredient deck.
D&C Red #19 in makeup and skincare
It is the shade in lipsticks, blushes, and other colour cosmetics. Its irritancy is rated separately at 0/5, which is low.