Characteristics
- INCI
- Ci 77491
- Ru.
- Iron Oxide Red
- CAS
-
1345-25-1, 1309-37-1, 1317-61-9, 1345-27-3, 52357-70-7
This is the substance number in the Chemical Abstracts Service registry. The CAS number uniquely identifies a substance regardless of language, trade name, or synonyms.
- EC
-
215-721-8, 215-168-2, 215-277-5, 215-722-3, 257-870-1
This is the substance number in the European chemical identification system (EC number), used in European regulatory databases including ECHA/CosIng.
- IUPAC
- Diiron Trioxide; Ferric Oxide
- Functions
- cosmetic colorant
- Irritancy
-
0 / 5
Irritation potential: 0–5, where 5 is the highest irritation rating for the ingredient.
More detail → - Comedogen.
-
0 / 5
Comedogenicity index: 0–5. A non-comedogenic ingredient (0–1) is unlikely to cause cosmetic acne.
More detail → - EU Restr.
-
IV/135
EU regulatory status: restricted use. The ingredient is permitted in EU cosmetics but its use and labelling are regulated.
More detail →
Who it's for
Description
If you’ve ever wondered how makeup gets that soft brick-red, rosy, or warm earthy tint without looking neon or overly bright, you’re probably looking at Ci 77491. This pigment is better known as red iron oxide, and it’s one of those quietly hardworking colorants that shows up in everything from foundations and blushes to lip products and eye makeup. It’s the kind of ingredient that doesn’t try to steal the show, but without it, a lot of our favorite shades would look a bit sad and flat.
Chemically speaking, it’s iron(III) oxide, also written as Fe2O3. The “red” part comes from the way it reflects light, giving products that natural-looking warm pigment people often want for skin tones and earthy makeup looks. It’s commonly used on its own or blended with yellow and black iron oxides to create a huge range of shades, especially in complexion products where a believable color match matters more than an Instagram-ready flash of color. In other words, it’s one of the main reasons your foundation can actually resemble your skin instead of a strange orange pancake.
From a safety point of view, iron oxides have a very solid reputation. They are inorganic pigments, so they don’t dissolve into your skin or behave like active ingredients; they mainly sit on the surface and do their job as colorants. They are widely approved for use in cosmetics around the world, including products used near the eyes and on the lips, because they’re considered very low risk when used as intended. That’s one reason they’re so popular in mineral makeup and in formulas aimed at sensitive skin — they bring the color without much drama.
And if you’re worrying about “iron” in the ingredient list sounding a bit alarming, don’t. In this case, it’s not the same thing as taking an iron supplement or dealing with anything remotely rusty on your face. Ci 77491 is simply a stable, dependable pigment that helps make makeup look more natural, more wearable, and less like face paint. Not glamorous, maybe, but definitely one of the unsung heroes of the cosmetics world.
More detail
Red Iron Oxide is the super common pigment that gives the familiar, "rust" red color. It is also the one that gives the pink tones in your foundation. Chemically speaking, it is iron III oxide (Fe2O3).
Products with Ci 77491 (9 189 total)
Most often found in Essence products (184 items)
