Hydrating Serum
Highlights
Key Ingredients
Skim through
Sephora Hydrating SerumIngredients 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.
We don't have description for this ingredient yet.The big brother of glycerin. It's also a natural moisturizing factor that reduces water evaporation from the upper layer of the skin and helps to keep water in the skin so that it stays nicely hydrated.
Compared to glycerin, it has a larger molecular structure (kind of a double glycerin). Thanks to this, it penetrates slower into the skin but gives longer lasting moisture and less sticky, better skin-feel.
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 a type of glycol that - according to the manufacturer - is an extremely good replacement for other glycols like propylene or butylene glycol. Its main job is to be a solvent, but it has also very good antimicrobial properties and acts as a true preservative booster. Also helps with skin hydration without stickiness or tacky feel.
- 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 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.
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 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).
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).
A helper ingredient that helps to make the products stay nice longer, aka preservative. It works mainly against fungi.
It’s pH dependent and works best at acidic pH levels (3-5). It’s not strong enough to be used in itself so it’s always combined with something else, often with potassium sorbate.
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.
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.
A big sugar molecule (polysaccharide) that is used as a natural thickening and gelling agent. It is similar to more commonly used Xanthan Gum, and the two are also often combined to create gel formulas or to stabilize emulsions.
You may also want to take a look at...
| what‑it‑does | solvent |
| what‑it‑does | perfuming |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | solvent | moisturizer/humectant |
| what‑it‑does | solvent |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | viscosity controlling |
| what‑it‑does | preservative |
| what‑it‑does | chelating |
| what‑it‑does | buffering |
| what‑it‑does | moisturizer/humectant |
| what‑it‑does | viscosity controlling |
| what‑it‑does | moisturizer/humectant |