The RX The Hylauronic 3
Ingredients overview
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Key Ingredients
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COSRX The RX The Hylauronic 3Ingredients 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.
Butylene glycol, or let’s just call it BG, is a multi-tasking colorless, syrupy liquid. It’s a great pick for creating a nice feeling product.
BG’s main job is usually to be a solvent for the other ingredients. Other tasks include helping the product to absorb faster and deeper into the skin (penetration enhancer), making the product spread nicely over the skin (slip agent), and attracting water (humectant) into the skin.
It’s an ingredient whose safety hasn’t been questioned so far by anyone (at least not that we know about). BG is approved by Ecocert and is also used enthusiastically in natural products. BTW, it’s also a food additive.
Propanediol is a natural alternative for the often used and often bad-mouthed propylene glycol. It's produced sustainably from corn sugar and it's Ecocert approved.
It's quite a multi-tasker: can be used to improve skin moisturization, as a solvent, to boost preservative efficacy or to influence the sensory properties of the end formula.
- 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
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 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.
A really multi-functional helper ingredient that can do several things in a skincare product: it can bring a soft and pleasant feel to the formula, it can act as a humectant and emollient, it can be a solvent for some other ingredients (for example it can help to stabilize perfumes in watery products) and it can also help to disperse pigments more evenly in makeup products. And that is still not all: it can also boost the antimicrobial activity of preservatives.
We don't have description for this ingredient yet.
A sugar beet-derived amino acid derivative with nice skin protection and moisturization properties. Betaine's special thing is being an osmolyte, a molecule that helps to control cell-water balance. It is also a natural osmoprotectant, meaning that it attracts water away from the protein surface and thus protects them from denaturation and increases their thermodynamic stability.
It also gives sensorial benefits to the formula and when used in cleansers, it helps to make them milder and gentler.
It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range.
Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415).
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).
This long-named, polymer molecule (big molecule from repeated subunits) is a helper ingredient that's good at emulsifying and stabilizing oils into water-based formulas. It also acts as a thickening and gelling agent that creates nice, non-sticky and supple textures. It works over a very wide pH range (3-12) and can be used to thicken up low-ph formulas, such as exfoliants. Its recommended used range is 0.3-3%.
PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. The sodium salt form of PCA is an important skin-identical ingredient and great natural moisturizer that helps the skin to hold onto water and stay nicely hydrated.
The sodium salt of lactic acid. It's a great skin moisturizer and also used to regulate the pH value of the cosmetic formula. It's a natural ingredient approved by both ECOCERT and COSMOS.
PCA stands for Pyrrolidone Carboxylic Acid and though it might not sound like it, it is a thing that can be found naturally in our skin. In fact, after amino acids, it is the second biggest NMF component of the skin with 12% being PCA of the NMF composition of normal skin. So similar to other NMFs, it's a skin goodie that helps the skin to hold onto water and stay nicely hydrated.
Glyceryl acrylate/acrylic acid copolymer is the fancy word for a common polymer (big molecule from repeated subunits), namely polyacrylic acid (aka carbomer when it comes to cosmetics) with glycerin attached to it in some places.
The main thing of this polymer is that it forms a hydrogel (trade named Lubrajel) that can sit on top of the skin and provide moisturizing, water-soluble ingredients such as glycerin to the skin. Think of it as a very thin, wet sponge that a cosmetic manufacturer can fill with good ingredients for your skin. It also works as a thickening agent (remember, it is a carbomer type of molecule), and can provide the skin with a nice slippery feel. It can also draw water to the skin (thank you, pendant glycerol groups!), providing skin hydration.
Also, don’t let people scare you into thinking polyacrylic acid is dangerous because of the toxicity of acrylic acid. Since acrylic acid is dangerous due to its ability to absorb into the skin (since it’s small), when you chain them together into a polymer (which is big), this danger is no longer significant.
It's the chemically chopped up version of normal lecithin. Most often it's used to create liposomes and to coat and stabilize other ingredients.
If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.
Also, it's an effective deodorant and a medium spreading emollient.
Serine is an amino acid that most often comes to the formula as part of a moisturizing complex. It's a non-essential amino acid (meaning that our body can synthesize it) and serves as a water-binding ingredient.
In general, amino acids are great skincare ingredients that play an important role in proper skin hydration but there is not much info out there about what specifically serine can do for the skin.
A non-essential amino acid (a building block of skin proteins like collagen or elastin) that hydrates the skin.
A non-essential amino acid (the building blocks of skin proteins, like collagen or elastin), that the body can produce itself, but its production decreases with age. When you put it all over your face, it works as a moisturizer and maybe more.
According to great skincare blog Futurederm, glycine might help with wound healing and tissue repair and when used together with other amino acids, leucine and proline it might improve wrinkles.
BTW, it's also a building block of a bunch of important and famous peptides, including copper-tripeptide-1, palmitoyl tripeptide-1 or palmitoyl hexapeptide-12.
It’s one of those little helper ingredients that makes sure the product stays the same over time. No color change or anything like that. 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.
A handy helper ingredient that helps water and oil to mix nicely together, aka emulsifier. It is especially recommended for protective, baby care and general purpose emollient creams.
It also helps to disperse insoluble particles (think color pigments or zinc/titanium dioxide sunscreen) nice and even in cosmetic formulas.
We don't have description for this ingredient yet.
Glutamic acid is a little molecule and non-essential (our body can synthesize it) amino acid with the important job of being a neurotransmitter in the human body meaning that it helps your nervous system work correctly.
As for what it's doing in cosmetics, Glutamic acids' main thing (similar to other amino acids) is being a humectant moisturizer and skin-conditioning agent (sidenote: if you attach lots of glutamic acid molecules, you get polyglutamic acid that is claimed to be a better than hyaluronic acid humectant). It also seems to affect skin barrier repair, however, it is not clear-cut in which direction.
The complication is that glutamic acid has two distinct forms, L-glutamic acid and D-glutamic acid, that are the mirror images of each other (think of it like your left and right hand). Studies show that a topical application of L-glutamic acid on damaged skin delayed skin repair, while D-glutamic acid application sped up skin repair. As both forms are used by the industry, it is a bit uncertain what you are getting with just glutamic acid on the ingredient list (but if it is a Shiseido group product, it is probably the goodie D-form :)).
Other than that, Glutamic acid can also be used as a pH adjuster and can be processed via biological pathways into pyrrolidone carboxylic acid, the sodium salt of which is a goodie and one of your skin’s natural moisturizing factors.
Citric acid comes from citrus fruits and is an AHA. If these magic three letters don’t tell you anything, click here and read our detailed description on glycolic acid, the most famous AHA.
So citric acid is an exfoliant, that can - just like other AHAs - gently lift off the dead skin cells of your skin and make it more smooth and fresh.
There is also some research showing that citric acid with regular use (think three months and 20% concentration) can help sun-damaged skin, increase skin thickness and some nice hydrating things called glycosaminoglycans in the skin.
But according to a comparative study done in 1995, citric acid has less skin improving magic properties than glycolic or lactic acid. Probably that’s why citric acid is usually not used as an exfoliant but more as a helper ingredient in small amounts to adjust the pH of a formulation.
We don't have description for this ingredient yet.
An essential amino acid that's also a key building block of collagen and elastin. When taken orally, it helps the digestive and intestinal tracts function more smoothly and also helps the absorption of nutrients. As for skincare, it is not clear what it does other than being a skin hydrator.
A semi-essential (infants cannot synthesize it, but adults can) amino acid that is one of the primary building blocks of hair keratin and skin collagen. It's a natural moisturizing factor, a skin hydrator and might also help to speed up wound healing.
Arginine usually has a positive charge (cationic) that makes it substantive to skin and hair (those are more negatively charged surfaces) and an excellent film former. Thanks to the positive charge, it also creates a complex with AHAs (AHAs like to lose a hydrogen ion and be negatively charged, so the positive and the negative ions attract each other) that causes a "time-release AHA effect" and reduces the irritation associated with AHAs.
A mild cleansing agent that's used mainly next to other cleansing agents (co-surfactant) to improve foam density and regulate viscosity.
A non-essential amino acid (meaning that our body can produce it) that's also one of the major building blocks of collagen. According to the Futurederm blog, it might be able to improve wrinkles when combined with other amino acids, glycine and leucine
One of the many types of ceramides that can be found naturally in the upper layer of the skin. Ceramides make up about 50% of the goopy stuff that's between our skin cells and play a super important role in having a healthy skin barrier and keeping the skin hydrated. It works even better when combined with its pal, Ceramide 1.
We wrote way more about ceramides at ceramide 1, so click here to know more.
It's one of the important lipids that can be found naturally in the outer layer of the skin. About 25% of the goopy stuff between our skin cells consists of cholesterol. Together with ceramides and fatty acids, they play a vital role in having a healthy skin barrier and keeping the skin hydrated.
Apart from being an important skin-identical ingredient, it's also an emollient and stabilizer.
A super common emollient that makes your skin feel nice and smooth. It comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. It’s a nice ingredient that just feels good on the skin, is super well tolerated by every skin type and easy to formulate with. No wonder it’s popular.
It's a type of lipid, a so-called sphingoid base that can be found naturally in the upper layer of the skin. It's found both in "free-form" and as part of famous skin lipids, ceramides.
There is emerging research about Phytosphingosine that shows that it has antimicrobial and cell-communicating properties and is considered part of the skin's natural defense system.
A 2007 study showed that Phytosphingosine even works against evil acne-causing bacteria, Propionibacterium acnes and shows promise as a complementing active ingredient in treating acne-prone skin thanks to its anti-inflammatory and antimicrobial activities.
A nice one to spot in the ingredient list. :)
A common multi-tasker fatty acid. It makes your skin feel nice and smooth (emollient), gives body to cream type products and helps to stabilize water and oil mixes (aka emulsions).
A common fatty acid that can be found in lots of plant oils. Its name, "oleic", means derived from olive oil, a plant oil rich in oleic acid, but avocado, macadamia and marula oils, just to name a few, are also oleic rich.
Its chemical structure is monounsaturated, meaning it has one double bond (cis-9) that makes it less kinky than polyunsaturated fatty acids with multiple double bonds. Less kinkiness means that oleic acid and OA-rich oils are a bit thicker and heavier than their LA-rich siblings.
Maybe this thickness is the reason that Oleic acid is considered comedogenic, and if you have acne-prone skin avoid OA-rich plant oils, and choose linoleic acid-rich versions instead.
The thickness of OA also means that OA-rich oils are considered more nourishing and moisturizing than their LA-rich counterparts, and are generally considered to be more suitable for dry, mature skin types.
As for oleic acid in its free form (and by free we mean that it is not bound up in a triglyceride structure like it is in oils), it mostly serves as an emulsifier or emulsion stabilizer in small amounts in regular cosmetic products. It is also quite well researched and is used in the pharmaceutical industry as a penetration enhancer.
Simply alcohol refers to ethanol and it's a pretty controversial ingredient. It has many instant benefits: it's a great solvent, penetration enhancer, creates cosmetically elegant, light formulas, great astringent and antimicrobial. No wonder it's popular in toners and oily skin formulas.
The downside is that it can be very drying if it's in the first few ingredients on an ingredient list.
Some experts even think that regular exposure to alcohol damages skin barrier and causes inflammation though it's a debated opinion. If you wanna know more, we wrote a more detailed explanation about what's the deal with alcohol in skincare products at alcohol denat. (it's also alcohol, but with some additives to make sure no one drinks it).
- 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
- It’s the second most researched AHA after glycolic acid
- It gently lifts off dead skin cells to reveal newer, fresher, smoother skin
- It also has amazing skin hydrating properties
- In higher concentration (10% and up) it improves skin firmness, thickness and wrinkles
- Choose a product where you know the concentration and pH value because these two greatly influence effectiveness
- Don’t forget to use your sunscreen (in any case but especially so next to an AHA product)
It’s a handy multi-tasking ingredient that gives the skin a nice, soft feel. At the same time, it also boosts the effectiveness of other preservatives, such as the nowadays super commonly used phenoxyethanol.
The blend of these two (caprylyl glycol + phenoxyethanol) is called Optiphen, which not only helps to keep your cosmetics free from nasty things for a long time but also gives a good feel to the finished product. It's a popular duo.
A chelating agent that helps to preserve cosmetic products by neutralizing the metal ions (especially iron) in the formula (that usually get into there from water). Its special thing is that it also acts as a biostatic and fungistatic agent and remains active even at high pH.
It is often coupled with antimicrobial glycols (such as propanediol) to create a "preservative free preservative system" for cosmetic products.
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| what‑it‑does | solvent |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | solvent |
| what‑it‑does | solvent |
| what‑it‑does | viscosity controlling |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | viscosity controlling |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | buffering | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant | viscosity controlling |
| what‑it‑does | emollient | emulsifying |
| what‑it‑does | preservative |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | chelating |
| what‑it‑does | emulsifying |
| irritancy, com. | 0, 1-2 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | buffering |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | surfactant/cleansing |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient |
| what‑it‑does | skin-identical ingredient | emollient |
| irritancy, com. | 0, 0 |
| what‑it‑does | emollient |
| what‑it‑does | skin-identical ingredient | cell-communicating ingredient | anti-acne | antimicrobial/antibacterial |
| what‑it‑does | emollient | viscosity controlling |
| irritancy, com. | 0, 2-3 |
| what‑it‑does | emollient | emulsifying |
| what‑it‑does | antimicrobial/antibacterial | solvent | viscosity controlling |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |
| what‑it‑does | exfoliant | moisturizer/humectant | buffering |
| what‑it‑does | moisturizer/humectant | emollient |
| what‑it‑does | chelating |