Herba Derm Hyaluronic Hydration Micellar Water

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

On the safety side, the Cosmetic Ingredient Review Expert Panel has concluded this ingredient to be safe as used in current cosmetic practices + concentrations.

Typical use levels in a formula run about 1-5%.

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

Some studies suggest betaine may support making skin tone more even.

Fun fact: Betaine naturally exists in the skin and the body. In cosmetic products, it can be either plant-derived (most commonly from sugar beets) or synthetically produced for consistency and stability.

Betaine is also known as trimethylglycine.

Interestingly, the size of the molecule affects its behavior:

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

Many serums use a blend of both weights so you can get surface hydration plus longer-lasting and deeper effects.

You'll typically see concentrations between 0.1-2% for this ingredient.

Specifically, saccharide Isomerate is a humectant. Humectants draw moisture from the air to our skin.

Research shows Saccharide Isomerate to be an effective moisturizer.

Studies show inulin may help with controlling your skin's natural microbiota when applied topically.

The antioxidant potential of inulin varies depending on the source.

Research shows centella asiatica can help increase Type I collagen production by increasing fibroblast production. Fibroblast helps form connective tissue.

The combination of all these properties makes centella asiatica leaf extract effective at soothing the skin.

Other components of centella asiatica leaf extract include Vitamin A, vitamin C, several B vitamins, and Asiatic Acid.

Recent studies found madecassoside may help prevent damage from UV rays by preventing UV-induced inflammation. Further research is needed.

This plant has been used as a medicine and in food for many centuries. As a medicine, it is used to treat burns, scratches, and wounds.

As a cosmetic ingredient, it grabs water and holds it in the upper layers of skin to smooth roughness and ease dehydration.

There's some clinical support for the NMF approach with a study showing that a cream built to mimic the skin's NMF significantly boosted hydration.

Safety-wise, this ingredient non-irritating, non-comedogenic, and non-phototoxic in testing, with minimal skin absorption.

It also works really well with other hydrators like glycerin or hyaluronic acid, and typical usage is somewhere between 0.2-4%.

Here's an interesting thing about Arginine: your skin converts it into urea through the Krebs-Henseleit urea cycle. Urea is one of the most effective humectants your skin naturally produces.

A clinical study showed applying 2.5% arginine hydrochloride to atopic dermatitis skin showed significant urea levels in the stratum corneum and improved moisture in just four weeks.

Arginine is also a precursor to nitric oxide; nitric oxide improves microcirculation and supports wound healing and collagen synthesis.

One study found that an amino acid complex containing Arginine reduced skin irritation, improved hydration, and accelerated skin repair in clinical / in-vivo studies.

Arginine itself is an amino acid and not a fatty acid, oil, or ester. On its own, it's not a direct food source for Malassezia, or the yeast that causes fungal acne.

Chelating agents help neutralize unwanted metals from affecting the formulation.

Sodium gluconate is water-soluble.

High percentages of Sodium Lactate can have an exfoliating effect.

Fun fact: Sodium Lactate is produced from fermented sugar.

This is why it works so well topically; PCA is a humectant that holds water in the stratum corneum and studies link higher skin PCA levels to better hydration + lower water loss. Interestingly, people show more PCA in summer and in normal vs dry skin.

Most of the benefits of this ingredient are related to hydration, softness, and barrier support.

A long-running review found that formulas with at least 2% PCA or its salts improved dry skin over both the short and long term. And the zinc salt is also used for its mild antimicrobial and astringent properties.

The salt forms are more common in cosmetics (like sodium PCA).

This ingredient is compatible with basically everything and pairs well with other humectants like glycerin or hyaluronic acid.

Usage-wise, it's typically used at low percentages (~0.2-2%).

The Cosmetic Ingredient Review Expert Panel has concluded PCA and its salts are safe as used and is non-irritating on skin even at high concentrations.

Research on a hydrogel with serine confirmed this serine got delivered to your stratum corneum and demonstrated enhanced skin moisturization.

Interestingly serine also helps your skin produce filaggrin, a protein that keeps your skin barrier strong and used to create collagen.

It's one of the small building blocks that make up your skin's natural moisturizing factor (NMF), or the built-in system that helps skin hold onto water. So its main job in a formula is to give the skin gentle hydration and help it feel more comfortable.

Typical amounts are very tiny: roughly 0.00004%-0.5% in leave on products and up to 1% in rinse-off ones.

The Cosmetic Ingredient Review panel has looked at this ingredient and found no evidence of it being a skin irritant or allergen at cosmetic levels.

Reviews of this ingredient have found it to be neither a dermal irritant nor a sensitizer.

Fun fact: Proline can be found in protein-rich foods like meat, fish, eggs, and dairy.

One study found histidine and carnosine to be a dynamic duo for your skin:

Oral histidine has also been found to help with filaggrin-deficit skin disorders such as atopic dermatitis.

Why is it considered a semi-essential amino acid? This is because adults are able to create it but children must get it from their diet.

Two structures of phenylalanine exist: L-phenylalanine and D-phenylalanine. L-phenylalanine is essential, this means our bodies cannot produce it naturally and we must get it from foods. Our bodies convert D-phenylalanine to neurotransmitters, and D-phenylalanine is found in our bodies naturally.

Some foods that contain L-phenylalanine include eggs, soybeans, beef, milk.

It's often paired with Sodium Anisate as the two create a broad-spectrum preservative system that is popular in "natural" formulations.

This ingredient is water-soluble.

The CIR Expert Panel for Cosmetic Ingredient Safety has concluded this ingredient to be non-irritated and there are no restrictions for use in EU cosmetics. The FDA also allows this ingredient to be used as a food-grade flavoring agent.

However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.

Due to this, citric acid is usually included in small amounts as a pH adjuster. This helps keep products slightly more acidic and compatible with skin's natural pH.

In skincare formulas, citric acid can:

While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.

Most citric acid used in skincare today is made by fermenting sugars (usually from molasses). This synthetic version is identical to the natural citrus form but easier to stabilize and use in formulations.

Read more about some other popular AHA's here:

The acidity of our skin is maintained by our glands and skin biome; normal pH level of skin is slightly acidic (~4.75-5.5).

Being slightly acidic allows our skin to create an "acid mantle". This acid mantle is a thin barrier that protects our skin from bacteria and contaminants.

Both potassium sorbate and sorbic acid can be found in baked goods, cheeses, dried meats, dried fruit, ice cream, pickles, wine, yogurt, and more.

You'll often find this ingredient used with other preservatives.