How To Read An Ingredient Label: 3 Top Tips From A Cosmetic Chemist

Becoming a master decoder of ingredient labels is practically par for the course for beauty insiders and fans. What used to be a mysterious blend of Latin-derived terms and a jumble of letters and numbers is now made easier than ever to read—thanks to ingredient databases, consumer interest, and education from the brands themselves. 

So sure, it's easier, but that's not to be confused with outright easy: Ingredient lists can still hide many truths about the product and its efficacy if you know how to read between the lines. 

"I would really hope that we evolve as a sector to get to a point where the consumer doesn't feel that they need to read the ingredient list to make sure that their product is safe," says clean cosmetic chemist Krupa Koestline in the most recent episode of Clean Beauty School. "But until then, I'm so impressed that consumers are asking the right questions." 

The order of the ingredients on the list matters—and, well, sometimes it doesn't. In the case of the first three ingredients, it does. "I look at the first three ingredients to let me know what it's composed of because the first three ingredients are basically what the product's majority is—like if it's butylene glycol, water, or aloe vera juice," she says. "And that's going to tell me a lot." 

"There's a misconception that active ingredients need to be high up on the list, and that's not true," she tells us. See, many believe that unless they see those buzzy ingredients high up there, it must not be formulated to levels that get the job done. That's simply untrue—and in several cases, when you see them at the top of that INCI [International Nomenclature of Cosmetic Ingredients] list it means that it can inflame and sensitize delicate skin. 

"Let's take vitamin C—there are some vitamin C derivatives that should not be used past a certain threshold; otherwise, they are going to cause sensitization and rashes," says Koestline. "Or retinol and alpha-hydroxy acids are another example. I tell people not to use high amounts of these because they are very potent—or at least be careful while using those." 

But it's not just sensitizing ingredients that you want to keep an eye out for. Take the very nourishing vitamin E, an antioxidant that protects and comforts the skin. "And then there's also a very cool example of vitamin E: If you use more than a certain percentage of vitamin E, it's going to cause rancidity, but if you use less than that, it's gonna prevent rancidity." 

People are eager for results. That's understandable! But with potency in your topical formulas often comes risks—not just for your skin's health (a la irritation) but for the formula's ability to deliver, stay shelf-stable, and remain tolerable for long periods of time. Because even if you have the most potent product available—what does it matter if it goes inactive stat?

Let's go back to vitamin C, that favorite antioxidant. One of the most famous forms of the vitamin is L-ascorbic acid. "That vitamin C is not stable over time, which is why we have so many different derivatives of vitamin C," she goes on to explain that you can find water-soluble derivatives (such as aminopropyl ascorbyl phosphate, which are perfect for water-based formulas) as well as oil-soluble derivatives (such as tetrahexyldecyl ascorbate, which are perfect for oil-based formulas). "And what these do is they increase the bioavailability and the penetration of vitamin C."