One of my favorite trends in skincare in the last decade is the shift away from a blind trust of marketing claims and a focus on truly understanding how skincare works and what it’s made of. As a teenager 20 years ago, the extent of my consumer research capacity was slowly wandering the aisles of Rite Aid and guessing which product looked like it worked best. This method was not effective. Now the SkincareAddiction subreddit has over a million subscribers.

That said, the push to understand and analyze the skincare products we buy can sometimes lead us astray; avid hobbyists will pore over the ingredients list of a new product to try to figure out exactly what it does, how it’s formulated, whether it works. Unfortunately, there’s only so much we can glean from a label, and “only so much” is actually not much at all. As someone on both the hobbyist consumer side and skincare formulator side, I want to break down specifically what you can and can’t learn about a product by reading its ingredient list.

CAN: Flag products that contain ingredients you’re allergic or sensitive to

This is the primary reason ingredients lists exist and are so strictly regulated. If you have a known allergy to an ingredient, you can easily tell at a glance whether this product contains it. Got a nut allergy? Sweet almond oil will appear as “Prunus Amygdalus Dulcis (Sweet Almond) Oil” on every ingredients list, so it’s easy to identify.

CAN’T: Figure out which ingredient in a product caused a bad reaction

If you know you have an allergy or sensitivity, ingredients lists are crucial. If a product breaks you out and you don’t know why, the ingredients list is not nearly as helpful. At best, you can collate the ingredients lists of several different products you’ve had the same negative reaction to and attempt to reverse-engineer your way to a conclusion, but even that method is sketchy. Certain ingredients (like glycerin, propylene glycol, and cetyl alcohol) tend to appear in many or most skincare products, which can give false positives.

Plus, a negative reaction can be caused by a specific combination of ingredients; for example, ingredient X is a problem only when combined with a penetration enhancer, or ingredients X, Y and Z are only minorly irritating on their own but cause a big reaction when used together. And, of course, sometimes skin breaks out because it’s weird and dramatic, and it didn’t like the way you added new products to your routine or touched it too much or looked at it wrong. We can’t always hold an ingredients list responsible for our skin’s histrionics.

CAN: Discover what beneficial ingredients are in a product

Sure, you can use the INCI list to learn that a product has your favorite ingredient: retinol, ceramides, licorice root extract – whatever great and well-researched ingredients a skincare addict could want. But you…

CAN’T: Discern how effective those ingredients are in the specific formulation

When it comes to skincare, formulation is king. Even if you know the exact percentage of an ingredient (and you rarely do), there are too many factors affecting its efficacy to draw any conclusions just from the label.

As an example, take these two products: Paula’s Choice Skin Perfecting 2% BHA and Paula’s Choice CLEAR Extra Strength 2% Salicylic Acid. Like many Paula’s Choice products, these two clearly state the percentage of the active ingredient – in this case, both have 2% salicylic acid – and yet one of them is called Extra Strength. I can personally attest that the Extra Strength version is noticeably stronger. Why? In this case, the second ingredient in the Extra Strength product is methylpropanediol, which functions as a penetration enhancer, helping the salicylic acid get deeper into the skin.

Another example is the fast-growing trend among ingredient manufacturers of specialized delivery vehicles for actives. Many actives are notoriously unstable, and chemical manufacturing companies are finding new ways to help get actives from the formula to the skin without breaking down. Often, this is done by creating microscopic capsules or protective matrices that surround the active and keep it safe until it’s rubbed into the skin. For example, let's say pure retinol in a formula degrades fast enough that only 25% of it is active by the time you apply it, but this new delivery vehicle means that the encapsulated retinol remains 80% active. The first formula could be 1% and the second could be 0.5%, but the second formula would still be much more potent.

CAN: Guess a very, very general idea of percentages

In the US and EU, ingredients lists are required to follow a very strict structure, in which all ingredients over 1% are listed from most to least. (Ingredients under 1% can go in any order.) So, you know the first ingredient on the list has the highest percentage, and probably the first four or five ingredients are more than 1%. You can also use ingredients that are not allowed above 1%, like phenoxyethanol, to figure out where that 1% marker starts.

CAN’T: Know how those percentages translate to efficacy, even if your guesses are correct

Let’s say you spot “Glycyrrhiza Glabra (Licorice) Root Extract” far down on an ingredients list, past phenoxyethanol. You can say with some certainty that this product has less than 1% licorice root extract. That means it’s at too low a percentage to be effective, right? Well, maybe, but maybe not.

As an example, let’s look at the Licorice Root Extract sold by Lotioncrafter. This is a raw ingredient meant to be used in a skincare formulation. They recommend using this product at a max concentration of 5%. If you look at the SDS, the product itself only contains 1.5%-3.5% licorice root; the rest is water, glycerin, and preservative. That means if you use this product at its max recommend concentration, the final skincare product will have just 0.075%-0.175% actual licorice root extract. That doesn’t mean it’s not effective. In this case, the raw extract is so incredibly concentrated that it’s most effective in very small amounts. Other types of licorice root extract may be extracted and concentrated in different ways, meaning there’s a different ideal percentage. There is truly no way to know by reading the label.

Some companies have found a creative way to get around this issue. Technically, you could take that 0.075% pure licorice root extract, mix it with a bunch of water, and now it’s called Licorice Root Water. You can easily claim that your product is 80% Licorice Root Water and put it first on the ingredients list, even though it still has just 0.075% licorice root extract. So really, given that life is short and every day is a gift, I can’t recommend spending your fleeting time on this earth trying to make guesses about percentages by looking at an INCI list. It’s just not worth it.

CAN: Identify a specific ingredient name

If, for example, you were dead-set on finding out which products have dimethicone in them, the ingredients list is the way to find out.

CAN’T: Know the form the ingredient is taking, or how it interacts with the rest of the formula

Let’s keep going with the dimethicone example. It’s an ingredient that gets some hate for allegedly forming a strong, immovable film over the skin. But did you there are approximately one billion different types of dimethicone? (Slight exaggeration.) Types of dimethicone are differentiated by a unit called centistoke, or cSt, which measures viscosity. Dimethicone can range from 0.5cSt, which is thinner than alcohol and evaporates completely when exposed to air, to 100,000cSt, which is thicker than molasses and forms a strong occlusive layer on the skin.

If the type of dimethicone is very low cSt, you really have nothing to worry about in regards to film-forming, because it’s what’s known as a volatile ingredient and evaporates easily at room temperature. But for the sake of argument, let’s say you somehow know that the dimethicone in this product is a higher cSt, and you’re worried it’ll create an occlusive layer that’s hard to wash off. You still don’t know how it’s interacting with the other ingredients in the formula.

While pure high cSt dimethicone does have that hard-to-remove film forming property, you really only ever see very large amounts of dimethicone in things like anti-frizz hair products. In almost every other type of beauty product, it will likely be used in small amounts alongside one or several emulsifiers. Emulsifiers are double-sided molecules that are attracted to hydrophilic (water-loving) molecules on one side, and hydrophobic (water-hating) molecules on the other. They’re the ingredients that keep your creams from separating like salad dressing. They also help those hydrophobic ingredients wash off, by ensuring they’ll play nicely with the water from your sink when you rinse. That means these emulsifiers can prevent dimethicone from forming an unbreakable film by making sure it washes off with your cleanser.

So, yes, you can use the ingredients list to identify that a product has some type of dimethicone in it. In the end, though, that doesn’t mean much.

CAN: Identify whether the company is following labelling regulations

Other than avoiding known allergens, this, to me, is the most useful application of the INCI list. The FDA has very strict guidelines for how ingredients are disclosed and labeled, which can be found here. If a company isn’t following these guidelines, it’s a red flag that they may not be following other guidelines or best practices. Some specific red flags to look for in US-based products:

• Plant-based ingredients aren’t listed with their official Latin name (for example, just “Sweet Almond Oil” instead of “Prunus Amygdalus Dulcis (Sweet Almond) Oil”)
• The word “organic” appearing in the ingredients list itself, like “Organic coconut oil” (organic ingredients should be noted with an asterisk)
• Alphabetical lists (which means they’re not listing ingredients from most to least)

(Sidenote: every country has its own labeling regulations, so this only works for products sold from within the US.)

CAN’T: Tell how well a product will work for you

If there’s one thing you take away from this two-thousand-word screed, it’s that it's hard to tell anything from an ingredients list. There are an infinite number of factors at play; it’s like looking out your window and using that information to predict the weather in three months. The only way to know how well a skincare product will work for you is to try it. The second-best way is to listen to the experiences of people who have tried it and who have similar skin to you. There is, unfortunately, no third-best way.

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