What a 1/5 rating means
On the comedogenic scale, a 1 sits at the safe end of the scale — clogging is unlikely for most people. That places D&C Red #7 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 #7 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 #7
It is a cosmetic colorant that gives makeup its shade. The calcium lake of D&C Red #6, one of the most common lipstick pigments in use. Rated 1, so the pigment itself is a low-risk component of a lip or cheek formula.
On a label it can read as D&C Red 7, D&C Red #7, D C Red 7, Ci 15850:1 — worth knowing when you scan an ingredient deck.
D&C Red #7 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.