What a 0/5 rating means
On the comedogenic scale, a 0 means it will not clog pores for essentially anyone, including very acne-prone skin. That places Isopropyl Alcohol 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 Isopropyl Alcohol near the end of a label is present in tiny amounts and matters far less than the same ingredient near the top.
About Isopropyl Alcohol
It is a solvent used to dissolve other ingredients or aid drying. A drying alcohol rated 0 for clogging but 4/5 for irritancy.
On a label it can read as Isopropyl Alcohol, Isopropanol — worth knowing when you scan an ingredient deck.
Isopropyl Alcohol in makeup and skincare
It is used in liquid liners, nail products, and some cleansers. Its irritancy is rated separately at 4/5, which is worth noting for sensitive or reactive skin.