Youth Dose Eye Treatment
Ingredients overview
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Kiehl’s Youth Dose Eye TreatmentIngredients explained
Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product.
It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water.
Once inside the skin, it hydrates, but not from the outside - putting pure water on the skin (hello long baths!) is drying.
One more thing: the water used in cosmetics is purified and deionized (it means that almost all of the mineral ions inside it is removed). Like this, the products can stay more stable over time.
Probably the most common silicone of all. It is a polymer (created from repeating subunits) molecule and has different molecular weight and thus different viscosity versions from water-light to thick liquid.
As for skincare, it makes the skin silky smooth, creates a subtle gloss and forms a protective barrier (aka occlusive). Also, works well to fill in fine lines and wrinkles and give skin a plump look (of course that is only temporary, but still, it's nice). There are also scar treatment gels out there using dimethicone as their base ingredient. It helps to soften scars and increase their elasticity.
As for hair care, it is a non-volatile silicone meaning that it stays on the hair rather than evaporates from it and smoothes the hair like no other thing. Depending on your hair type, it can be a bit difficult to wash out and might cause some build-up (btw, this is not true to all silicones, only the non-volatile types).
- A natural moisturizer that’s also in our skin
- A super common, safe, effective and cheap molecule used for more than 50 years
- Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
- Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
- High-glycerin moisturizers are awesome for treating severely dry skin
A white, elastomeric silicone powder that gives a nice silky and powdery feel to the products. It also has some oil and sebum absorption capabilities.
This bamboozling INCI name is given to a spherical silicone powder that has an elastic silicone rubber inner part and a harder silicone resin outer part.
It gives formulas a uniquely soft, silky feeling, and has a mattifying and soft focus effect. It is available in different particle sizes and the larger the particle the more line/pore filling effect the powder has.
A "green chemical" developed by L'oreal in 2006. It comes from the sugar molecule, xylose that can be found in beechwood.
According to L'Oreal's claims, Pro-Xylane can boost the production of important skin-building blocks called GAGs (aka glycosaminoglycans, important NMFs) in the extracellular matrix (the goopy stuff between our skin cells) that results in better hydrated and firmer skin.
An emollient ester with a rich and creamy but non-greasy skin feel. It makes skin supple and protects dry skin.
- It's a helper ingredient that improves the freeze-thaw stability of products
- It's also a solvent, humectant and to some extent a penetration enhancer
- It has a bad reputation among natural cosmetics advocates but cosmetic scientists and toxicology experts do not agree (read more in the geeky details section)
A form of skincare superstar, vitamin C. If you do not know why vitamin C is such a big deal in skincare, we have a really detailed, geeky description that's good to read. :)
So now you know that because pure vitamin C is such a diva (very unstable and hard to formulate) the cosmetic industry is trying to come up with some derivatives that have the badass anti-aging properties of vitamin C (antioxidant protection + collagen boosting + fading hyperpigmentation) but without the disadvantages. This is a hard task, and there is not yet a derivative that is really proven to be better in every aspect, but Ascorbyl Glucoside is one of the best options when it comes to vitamin C derivatives. Let's see why:
First, it's really stable and easy to formulate, so the problems that come with pure vitamin C are solved here.
Second, in vitro (meaning made in the lab, not on real humans) studies show that ascorbyl glucoside can penetrate the skin. This is kind of important for an anti-aging ingredient to do the job, so this is good news, though in-vivo (made on real humans) studies are still needed.
Third, in-vitro studies show that after ascorbyl glucoside is absorbed into the skin it is converted to pure vitamin C (though the rate of conversion is still a question mark). It also shows all the three anti-aging benefits (antioxidant protection + collagen boosting + fading hyperpigmentation) that pure vitamin C does.
Bottom line: ascorbyl glucoside is one of the best and most promising vitamin C derivatives that shows similar benefits to that of pure vitamin C, but it's less proven (in vivo vs. in vitro studies) and the extent of the benefits are also not the same.
A clear, slightly yellow, odorless oil that's a very common, medium-spreading emollient. It makes the skin feel nice and smooth and works in a wide range of formulas.
The snappily named Lauryl Peg-9 Polydimethylsiloxyethyl Dimethicone is a silicone emulsifier fluid whose main thing is being a good dispersant for powders such as mineral UV filters or color pigments.
According to the manufacturer Kobo, this partly water- and partly oily soluble form of dimethicone helps filters like Titanium Dioxide and Zinc Oxide disperse more evenly and thus provide better UV protection while also minimizing any white-cast that often comes hand-in-hand with mineral filters.
This is why it can also be found in makeup products like eyeshadows and concealers, as it helps disperse color pigments in the same way.
Porous spherical microbeads (tiny little balls) that can give an elegant silky texture to the products. They are also used to scatter light to reduce the look of fine lines on the skin, as well as to absorb excess oil and give a matt finish.
Boron Nitride is a graphite-like, crystalline material that has light-diffusing and texture improving properties. It is quite the multi-tasker as it can blur imperfections, add an exceptional creamy feel to products and act as a mattifying agent.
In powder makeup products (think blushers, highlighters), it enhances the skin feel and improves the color pay-off. In lipsticks, it gives a creamy feel and a better color on the lips.
Ci 77891 is the color code of titanium dioxide. It's a white pigment with great color consistency and dispersibility.
A super versatile and common mineral powder that comes in different particle sizes. It is a multi-tasker used to improve skin feel, increase product slip, give the product light-reflecting properties, enhance skin adhesion or serve as an anti-caking agent.
It is also the most commonly used "base" material for layered composite pigments such as pearl-effect pigments. In this case, mica is coated with one or more metal oxides (most commonly titanium dioxide) to achieve pearl effect via the physical phenomenon known as interference.
It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.
It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic.
Other than having a good safety profile and being quite gentle to the skin it has some other advantages too. It can be used in many types of formulations as it has great thermal stability (can be heated up to 85°C) and works on a wide range of pH levels (ph 3-10).
It’s often used together with ethylhexylglycerin as it nicely improves the preservative activity of phenoxyethanol.
A silicone emulsifier that helps to create water in silicone emulsions.
A handy white powder that likes to absorb oily things. It has great oil and sebum absorption (aka mattifying) abilities and can also act as a thickening agent in the oil phase of a formula.
We don't have description for this ingredient yet.
Bismuth Oxychloride has been around since the 1950s and it was one of the first synthetic materials to give a pearl-like effect in cosmetic products. It is a white powder with a fabulous sheen and a nice skin feel and it is still very popular in decorative cosmetics.
It has one major drawback: it is sensitive to light. Upon prolonged UV exposure, it can lose its sheen and become gray.
It’s the - sodium form - cousin of the famous NMF, hyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here. The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.
As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution".
In spite of this, if you search for "hyaluronic acid vs sodium hyaluronate" you will find on multiple places that sodium hyaluronate is smaller and can penetrate the skin better. Chemically, this is definitely not true, as the two forms are almost the same, both are polymers and the subunits can be repeated in both forms as much as you like. (We also checked Prospector for sodium hyaluronate versions actually used in cosmetic products and found that the most common molecular weight was 1.5-1.8 million Da that absolutely counts as high molecular weight).
What seems to be a true difference, though, is that the salt form is more stable, easier to formulate and cheaper so it pops up more often on the ingredient lists.
If you wanna become a real HA-and-the-skin expert you can read way more about the topic at hyaluronic acid (including penetration-questions, differences between high and low molecular weight versions and a bunch of references to scientific literature).
A little helper ingredient that works as a preservative. It works against bacteria and some species of fungi and yeast. It's often combined with IT-preservative, phenoxyethanol.
A helper ingredient that is used as a bulking and viscosity controlling agent. It is also an emulsion stabilizer in water-in-oil emulsions, where water droplets are dispersed in the continuous oil phase and not the other way round.
It can also be used as a heat generating agent in water-less formulas as it has an instant heat-generating chemical reaction with water.
The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right.
For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.
BTW, lye is not something new. It was already used by ancient Egyptians to help oil and fat magically turn into something else. Can you guess what? Yes, it’s soap. It still often shows up in the ingredient list of soaps and other cleansers.
Sodium hydroxide in itself is a potent skin irritant, but once it's reacted (as it is usually in skin care products, like exfoliants) it is totally harmless.
Hello, our favorite molecule that helps us wake up in the morning and then keeps us going through the day. As a super well-known stimulant from coffee, tea and plenty of other soft drinks, Caffeine needs no introduction. So we will skip right to the part where we talk about what the hell it does in so-so many cosmetic products.
Looking at the research, we were surprised to find how versatile Caffeine is. It is a small, water-loving molecule with pretty good skin penetration abilties. Once in the skin, it has nice antioxidant properties, meaning that it reduces the formation of evil free radicals and it might even be useful in preventing UV-induced skin cancers.
A well-known thing about Caffeine is that it improves the microcirculation of the blood vessels. Though conventional wisdom and anecdotal evidence says that this property is helpful for dark under-eye circles and puffy eyes, we have to mention that the double-blind research we have found about a 3% caffeine gel concluded that "the overall efficacy of the selected caffeine gel in reducing puffy eyes was not significantly different from that of its gel base." But you know, the proof is in the pudding.
Another thing Caffeine is used for in body care products is its anti-cellulite effects. In theory, it can speed up the lipolysis process (the "fat burning" by our cells) and stimulate the draining lymph system that might lead to the improvement of cellulite. But here again, the evidence that it actually makes a measurable, let alone visible, improvement on actual human beings is limited (we could find only some animal skin studies or caffeine being combined with other actives).
Last, but not least, we have to write about caffeine and hair growth. The theory is that it can inhibit the activity of the 5-α-reductase enzyme that plays an important role in hair loss and allows a renewed growth phase of the hair. We have found some recent and promising research to back this up. A 2017 study compared a 0.2% caffeine liquid with a 5% Minoxidil (an FDA approved active to treat baldness) solution and found that "a caffeine-based topical liquid should be considered as not inferior to minoxidil 5% solution in men with androgenetic alopecia", or English translation means that the caffeine liquid was pretty much as good as the FDA-approved Minoxidil stuff. Not bad!
Overall, we think that caffeine is a very versatile and biologically active ingredient. Even though some of its effects are more hyped up than backed up, it is still a nice to have on many ingredient lists.
It's an ester form of vitamin A (retinol + palmitic acid) that belongs to the "retinoid family". The retinoid family is pretty much the royal family of skincare, with the king being the FDA-approved anti-aging ingredient tretinoin. Retinol is also a very famous member of the family, but it's like Prince George, two steps away from the throne. Retinyl palmitate will be then Prince Charlotte (George's little sister), quite far (3 steps) away from the throne.
By steps, we mean metabolic steps. Tretinoin, aka retinoic acid, is the active ingredient our skin cells can understand and retinyl palmitate (RP) has to be converted by our metabolic machinery to actually do something. The conversion is a 3 step one and looks like this:
retinyl palmitate --> retinol -- > retinaldehyde --> all-trans-retinoic acid
As we wrote in our lengthy retinol description the problem is that the conversion is not terribly effective. The evidence that RP is still an effective anti-aging ingredient is not very strong, in fact, it's weak. Dr. Leslie Baumann in her fantastic Cosmetic Dermatology book writes that RP is topically ineffective.
What's more, the anti-aging effectiveness is not the only questionable thing about RP. It also exibits questionable behaviour in the presence of UV light and was the center of a debate between the non-profit group, EWG (whose intentions are no doubt good, but its credibility is often questioned by scientists) and a group of scientists and dermatologists lead by Steven Q. Wang, MD, director of dermatologic surgery at Memorial-Sloan Kettering Cancer Centre.
Dr. Leslie Baumann wrote a great review of the debate and summarized the research available about retinyl palmitate here. It seems that there is a study showing RP being photo protective against UVB rays but there is also a study showing RP causing DNA damage and cytotoxicity in association with UVA.
We think that the truth lies somewhere in the middle, and we agree with Dr. Baumann's conclusion: "sufficient evidence to establish a causal link between RP and skin cancer has not been produced. Nor, I’m afraid, are there any good reasons to recommend the use of RP". We would add especially during the day!
Bottom line: If you wanna get serious about retinoids, RP is not your ingredient (retinol or tretinoin is!). However, if you use a product that you like and it also contains RP, there is no reason to throw it away. If possible use it at night, just to be on the safe side.
We wholeheartedly support the rise of seedless grapes as fruit snacks, but when it comes to skincare, we are big fans of the seeds.
They contain the majority of the skin goodies that - similar to green tea - are mostly polyphenols (but not the same ones as in tea). The most abundant ones in grape are called proanthocyanidins, and 60-70% of them are found in the seeds (it's also often abbreviated as GSP - grape seed proanthocyanidins). In general, the darker the fruit, the more GSPs and other flavonoids it contains.
So what's so special about GSPs? Well, they are super-potent antioxidants, much stronger than Vitamin C or Vitamin E. And if that's not enough, GSPs and other flavonoids in grape also show UV protecting and anti-cancer properties.
It's definitely a goodie to spot on the INCI list.
We don't have description for this ingredient yet.
Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate is an antioxidant molecule used in small amounts (less than 0.8%) to help products stay nice longer. More specifically, it is great at preventing discoloration or other types of oxidative degradation. It is a trendy alternative to often bad-mouthed synthetic antioxidant and stabilizer, BHT.
A handy helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.
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).
Adenosine is an important little compound in our body that has a vital cell-signalling role. Research on smearing it on our face is also promising and shows so far a couple of things:
- It can help with wound healing
- It’s a good anti-inflammatory agent
- It might even help with skin’s own collagen production and improve skin firmness and elasticity
- It helps with barrier repair and protection
- It might be even useful for the hair helping with hair thickness and hair growth
A multi-functional, silky feeling helper ingredient that can do quite many things. It's used as an emulsion stabilizer, solvent and a broad spectrum antimicrobial. According to manufacturer info, it's also a moisturizer and helps to make the product feel great on the skin. It works synergistically with preservatives and helps to improve water-resistance of sunscreens.
- Primary fat-soluble antioxidant in our skin
- Significant photoprotection against UVB rays
- Vit C + Vit E work in synergy and provide great photoprotection
- Has emollient properties
- Easy to formulate, stable and relatively inexpensive
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| what‑it‑does | solvent |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | cell-communicating ingredient |
| what‑it‑does | emollient |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 0 |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | emollient | perfuming |
| what‑it‑does | emulsifying | surfactant/cleansing |
| what‑it‑does | colorant |
| irritancy, com. | 0, 0 |
| what‑it‑does | colorant |
| what‑it‑does | preservative |
| what‑it‑does | emulsifying |
| what‑it‑does | viscosity controlling | emollient |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | colorant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | preservative | antimicrobial/antibacterial |
| what‑it‑does | viscosity controlling |
| what‑it‑does | buffering |
| what‑it‑does | antioxidant | perfuming |
| what‑it‑does | cell-communicating ingredient |
| irritancy, com. | 1-3, 1-3 |
| what‑it‑does | antioxidant | antimicrobial/antibacterial |
| what‑it‑does | exfoliant |
| what‑it‑does | antioxidant | preservative |
| what‑it‑does | chelating |
| what‑it‑does | colorant |
| irritancy, com. | 0, 0 |
| what‑it‑does | cell-communicating ingredient |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |