Hydro+ Eye Gel
Ingredients overview
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Key Ingredients
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Curology Hydro+ Eye GelIngredients 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.
A clear, colorless liquid that works as a solvent and viscosity decreasing ingredient. It also has great skin-moisturizing abilities.
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.
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 a little helper ingredient coming from corn, rice or potato starch that can help to keep skin mat (absorbent), to stabilise emulsions, and to keep the product together (binding).
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.
- 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
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%.
- It’s naturally in our skin and behaves there like a sponge
- It can bind up to 1000 times its own weight in water
- It is a big molecule from repeated subunits (polymer) so different molecular weight versions exist (unfortunately there is no way to determine MW from INCI list only)
- High-molecular-weight-HA (>500 kDa) is an excellent surface hydrator, skin protectant and can act as an osmotic pump helping water-soluble actives to penetrate deeper into the skin
- Low-molecular-weight-HA (< 500 kDa) can hydrate the skin somewhat deeper though it is still a big molecule and works mainly in the epidermis (outer layer of the skin)
- Low-molecular-weight-HA might also help the skin to repair itself by increasing its self-defense (~ 200kDa used in the study)
- Ultra-low-molecular-weight-HA (<50kDa) is a controversial ingredient and might work as a pro-inflammatory signal molecule
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).
It's a super small, chemically chopped up version of sodium hyaluronate. Its trade name is miniHA, and its molecular weight is 10 kDa. This counts as really tiny given that "normal" HA has a molecular weight of 0.5-2 million Da.
To be honest, low molecular weight (LMW), and especially this ultra-low molecular weight HA is a controversial ingredient. On the upside, it can penetrate the skin better (though 10kDa still counts as big!) and might be able to moisturize the deeper layers of the skin where normal HA cannot get. Also, according to the manufacturer of miniHA, it has better antioxidant activity than a 1.6MDa version HA and it also has better sun protection and after-sun repair abilities than the higher MW versions. It also works in synergy with higher molecular weight versions, and the combination of 0.1% 1.45MDa-HA + 0.1% 380 kDa-HA + 0.1% miniHA hydrated the skin significantly better than 0.3% 1.45MDa-HA alone.
On the downside, the biological role of LMW-HA in the skin is being a pro-inflammatory signaling agent and there is a study by another manufacturer called Evonik showing that HA versions with smaller than 50kDa molecular weight might be pro-inflammatory when put on the skin. Granted, the study was only done on reconstituted human epidermis, so it might or might not be like this on real human skin.
If you wanna get confused and read much more about hyaluronic acid and what the different molecular weight versions might or might not do, click here and read our excruciatingly long description.
Sodium Acetylated Hyaluronate is a variation of current IT moisturizer, Hyaluronic acid, where some water-loving -OH groups are replaced by amphipathic (partly water-loving and partly water-hating) acetyl groups. The modified molecule is claimed to have even better moisture retention ability than normal HA and better affinity to the skin surface.
The better affinity comes from the acetyl groups that act as tiny "anchors" to attach the HA molecule to the skin. Staying on top of the skin better and longer means longer-lasting surface hydration and improved elasticity. It is also less sticky and more cosmetically elegant than normal HA, so no wonder the nickname of this molecule is super hyaluronic acid.
It's a special "cross-linked" from of IT-moisturizer, hyaluronic acid (HA). Cross-linked means that "normal" HA pieces (1-2 million Da molecular weight) are chemically bound togeather to create a big, "infinite" mesh.
The special HA mesh has a remarkable water-binding capacity, 5 times more than the already crazy water-binding capacity of "normal" HA. This water filled crosslinked HA gel forms a smooth film on the skin and continuously delivers the bound water, so it gives long-term moisturizing benefits.
Btw, crosslinking HA was developed for dermal fillers (as crosslinking helps their longevity), and this guy is the topical version of FDA approved dermal filler called Hylan B gel. Smearing crosslinked version all over ourselves is a newish thing, and incoming evidence so far suggests that it's a great idea, even better than normal HA.
A very recent, 2016 research article compared the topical moisturizing effect of crosslinked HA (not Hylan B gel specifically, but something called Resilient HA or RHA), HMW-HA and LMW-HA and found that "TEWL (that is trans-epidermal water loss, the water that evaporates from the skin) was reduced by 27.8% with RHA, and by 15.6% with HMW HA, but increased by 55.5% with LMW HA." (You can read much more about HMW and LMW HA here in the geeky details section.)
All in all, we think Sodium Hyaluronate Crosspolymer is an awesome version of HA, probably superior to traditional versions, so be happy to spot it on the ingredient list.
A very stable and promising form of the skincare superstar, Vitamin C. If you do not know why Vitamin C is such a big deal in skin care, you can catch up here. In short, Vitamin C has three proven magic abilities: antioxidant, collagen booster, and skin brightener. The problem, though, is that it's very unstable, turns brown and becomes ineffective in no time (after a few month) and the cosmetics industry is trying to come up with smart derivatives that are stable and have the magic properties of pure Vitamin C.
Ethyl Ascorbic Acid or EAC for short is an "etherified derivative of ascorbic acid" that consists of vitamin C and an ethyl group bound to the third carbon position. This makes Vitamin C very stable and soluble in both water and oil.
However, for a Vitamin C derivative to work it's not enough just to be stable, they also have to be absorbed into the skin and be converted there to pure Vitamin C. We have good news regarding the absorption: on top of manufacturer claims, there is some data (animal study) demonstrating in can get into the skin, and it seems to be better at it than Ascorbyl Glucoside, another vitamin C derivative.
Regarding conversion, we can cite only a manufacturers claim saying that EAC is metabolized in the skin into pure ascorbic acid (and the ascorbic acid content of EAC is very high - 86,4% - compared to the usual 50-60% Vitamin C content of other derivatives).
As for the three magic abilities of Vitamin C, we again mostly have only the manufacturer's claims, but at least those are very promising. EAC seems to have both an antioxidant and anti-inflammatory effect, and it's claimed to be able to boost the skin's collagen production. The strong point of EAC though is skin brightening. On top of manufacturer claims, there is also clinical in-vivo (tested on real people) data showing that 2% EAC can improve skin tone and whiten the skin.
Overall, Ethyl Ascorbic Acid is a very promising but not a fully proven Vitamin C derivative. It's worth a try, especially if you are after Vitamin C's skin-brightening effects.
A four amino acid peptide with the amino sequence of glycine-glutamine-proline-arginine. It is attached to palmitic acid (a fatty acid) to increase oil solubility and skin penetration.
It works by reducing the production of the signal molecule, interleukin-6 (IL-6) which promotes inflammation in the skin and less inflammation means slower degradation of important things (like collagen) that results in younger looking skin for a longer time.
It works in synergy with its pal, Palmitoyl Tripeptide-1 in the famous Matrixyl 3000 complex. You can read some more about the famous duo here.
A really famous peptide that is part of Matrixyl 3000, the most sold peptide complex in the word. Before we go and find out what the big deal with Matrixyl 3000 is, let's just focus on Palmitoyl Tripeptide-1 itself for a bit.
It's a small three amino acid (they are the building blocks of all proteins) peptide with the amino sequence of glycine-histidine-lysine, or GHK. GHK is attached to palmitic acid (a fatty acid) to increase oil solubility and skin penetration.
The GHK part is the important one as it's a type I collagen fragment. When collagen naturally breaks down in the skin, the resulting peptide fragments signal to the skin that it should get to work and create some nice, new collagen. Adding in collagen fragment peptides, like GHK, might trick the skin into thinking that collagen has broken down and it's time to create some more.
Therefore, Palmitoyl Tripeptide-1 is believed to be able to stimulate collagen production in the skin, and more collagen means fewer wrinkles and younger looking skin.
In Matrixyl 3000, Palmitoyl Tripeptide-1 is coupled with Palmitoyl Tetrapeptide-7 and the duo works in synergy to reduce wrinkles and give younger looking skin. According to the manufacturer's in-vivo (made on real people) test, applying 3% Matrixyl 3000 twice a day for 2 months resulted in all of the following things:
- 39.4% reduction in surface occupied by deep wrinkles
- 32.9% reduction in main wrinkle density
- 19.9% reduction in main wrinkle average depth
- 16% improvement in roughness
- 16.2% in lifting effect
- 5.5% improvement in elasticity
- 15.5% improvement in skin tone
Manufacturer results, of course, always have to be taken with a pinch of salt, but if you like peptides, the Matryxil 3000 duo is one of the best-proven and most well-known ones and it's something that is worth trying.
Camellia Oleifera is a type of green tea plant that's mostly known for the oil that comes from its seeds. As for the leaves, it has similar properties as the better known and more often used Camellia Sinensis leaves. You can read all the geeky details about green tea and why it's awesome by clicking here, but in short, it has antioxidants and anti-inflammatory magic properties.
An ester that comes from Cetearyl alcohol and the fatty acids of olive oil. It often comes to the formula coupled with Sorbitan Olivate as the two together form the well-known, natural emulsifier trade named Olivem 1000.
Other than helping oil and water to blend, the main thing of Olivem 1000 is generating liquid crystal structures that are similar to the lipid structures of the stratum corneum (the outermost layer of the skin). Thanks to this, Olivem 1000 doubles as an active ingredient with significant moisturizing, barrier-repairing and soothing properties.
It also helps to deliver water-soluble actives such as caffeine more effectively, and can even boost SPF in sunscreen formulas. Its typical use level is 1-5% and has wide compatibility with other actives and oils.
Overall, a real multi-tasker with nice sensorial properties. No wonder it is so popular.
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 big molecule created from repeated subunits (a polymer of acrylic acid) that magically converts a liquid into a nice gel formula. It usually has to be neutralized with a base (such as sodium hydroxide) for the thickening to occur and it creates viscous, clear gels that also feel nice and non-tacky on the skin. No wonder, it is a very popular and common ingredient. Typically used at 1% or less in most formulations.
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.
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.
A nice little helper ingredient that can thicken up cosmetic products and create beautiful gel formulas. It's derived from cellulose, the major component of the cell wall of green plants. It is compatible with most co-ingredients and gives a very good slip to the formulas.
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.
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.
It's a common little helper ingredient that helps water and oil to mix together. Also, it can help to increase the solubility of some other ingredients in the formula.
A common little helper ingredient that helps water and oil to mix together, aka emulsifier.
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.
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.
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.
An ester coming from sorbitol and the fatty acids of olive oil. It is part of the popular emulsifier trade named Olivem 1000 that is well-known for generating biomimetic liquid crystal structures. We have more info on Olivem 1000 at Cetearyl Olivate >>
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).
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| what‑it‑does | solvent |
| what‑it‑does | solvent |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | antioxidant | perfuming |
| what‑it‑does | solvent |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | antioxidant | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | cell-communicating ingredient |
| what‑it‑does | cell-communicating ingredient |
| what‑it‑does | antioxidant | soothing |
| what‑it‑does | emulsifying |
| what‑it‑does | moisturizer/humectant | emollient |
| what‑it‑does | viscosity controlling |
| irritancy, com. | 0, 1 |
| what‑it‑does | buffering |
| what‑it‑does | preservative |
| what‑it‑does | viscosity controlling |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | preservative |
| what‑it‑does | emulsifying | surfactant/cleansing |
| irritancy, com. | 0, 0 |
| what‑it‑does | emulsifying | surfactant/cleansing |
| what‑it‑does | buffering |
| what‑it‑does | buffering | moisturizer/humectant |
| what‑it‑does | emulsifying |
| irritancy, com. | 0, 1-2 |
| what‑it‑does | emulsifying |
| what‑it‑does | viscosity controlling |