Why do acne products use the same few actives?

The US acne monograph permits five named active ingredients: benzoyl peroxide, resorcinol, resorcinol monoacetate, salicylic acid and sulfur. Anything sold as an over-the-counter acne treatment on that route has to choose from them, which is why the shelf looks repetitive. It is a closed list rather than a popularity contest, and one entry on it is not even permitted on its own.

Acne actives: the whole permitted list is five ingredients

Walk a drugstore acne aisle and the packaging varies enormously while the active ingredient varies hardly at all. That is not laziness. It is the regulation, and it is short enough to quote almost in full.

The whole list

The monograph permits, in this order: “Benzoyl peroxide, 2.5 to 10 percent”, resorcinol at 2 percent, resorcinol monoacetate at 3 percent, “Salicylic acid, 0.5 to 2 percent”, and “Sulfur, 3 to 10 percent”.

Five ingredients. There is no sixth.

What that means about everything else on the pack

An acne product is a drug in the US, because treating acne is a drug claim. A product taking the monograph route has to pick from the five, at the stated strength, and print it in a Drug Facts panel.

That is the useful reframing. Niacinamide, zinc, tea tree, centella and the rest can be present and can be the whole story the marketing tells, but they are not the active. The active is one of five names and it is printed on the back with a number next to it.

The odd one out

Four of the five stand alone. One does not: resorcinol is permitted only “when combined with sulfur in accordance with § 333.320(a)”.

The combinations section exists to hold that pairing and no other, and it changes sulfur too. Alone, sulfur runs to 10 percent. Combined with resorcinol it is capped lower, at “Sulfur, 3 to 8 percent, when combined with resorcinol or resorcinol monoacetate in accordance with § 333.320”.

So on the shelf, resorcinol never appears by itself. If you see it without sulfur, the product is not on the monograph.

Why the list has not grown

New actives are not added by demand. A substance joins a monograph through a regulatory process rather than through popularity, and in the meantime a company with a novel ingredient has two options: get it approved as a new drug, or sell it as a cosmetic and make no acne claim.

The second is common, and it explains the careful wording on a lot of packaging. A product that says it clarifies or purifies rather than treats acne has told you which route it took.

Which cosmetic ingredients are actually drugs covers the wider category, and whether sulfur earns its place takes one of the five on its own terms.

Sources

21 CFR 333.310: Acne active ingredients US Food and Drug Administration, via eCFR · ecfr.gov The complete list of permitted acne actives and their concentration ranges.

21 CFR 333.320: Permitted combinations of active ingredients US Food and Drug Administration, via eCFR · ecfr.gov The only two combinations the acne monograph permits.