Centellian24 Madeca Gel Serum Hyalron Dew

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.

Methylpropanediol is able to add a bit of moisture to the skin. It also helps other ingredients be better absorbed into the skin, such as salicylic acid.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

Cornflowers have been used in traditional European medicine to treat eye inflammation.

Fun fact: Cornflowers were used to determine if love was returned. Young men would wear cornflowers and if the color faded quickly, it meant the love was not reciprocated.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Having moisturized skin helps improve the skin barrier. Your skin barrier helps protect against irritants and bacteria.

You'll usually find this in concentrations between 0.2-5%.

As an antioxidant, asiatic acid helps protect our skin against damaging environmental factors.

Cimicifuga Racemosa Root has been used in traditional indigenous medicine.

Other colloquial names for this plant include black bugbane, black snakeroot, rattle-top, or fairy candle

Research shows silybin extract can protect skin from UV-induced oxidative stress and also works to calm inflammation.

There's also growing interest in its potential for acne-prone skin. One 12-month study on over 50 subjects using topical Silybum Marianum Extract found a ~60% reduction in acne lesions over the course of a year.

More recently, a 2025 study found silybin significantly boosted collagen III and hyaluronic production in skin tissue with results comparable to retinol; please know retinol is still the gold standard and silybin research has a long ways to go to confirm whether it can replace retinol.

In terms of tolerability, one large study of over 4,000 participants rated this ingredient tolerance as "good" or "very good" in about 95% of participants.

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.

Early research also shows that caffeine can help calm redness, soothe irritated skin, and support hair growth by stimulating microcirculation in the scalp.

You might have seen eye creams marketing caffeine as a depuffing ingredient. This is because it is a vasoconstrictor meaning it can temporarily constrict blood vessels, though clinical evidence for this specific use is still limited.

Most skincare products contain this ingredient at concentrations between 1-6%. It is able to penetrate skin easily regardless of skin type or thickness.

Just so you know, a very small number of case reports describe caffeine-induced allergy. This ingredient is generally well-tolerated, non-irritating, and non-sensitizing for the majority of people.

As a polysaccharide, Maltodextrin has moisturizing properties. Polysaccharides are a type of carbohydrate. The top layer of skin uses polysaccharides to retain water, keeping the skin hydrated.

Maltodextrin is water soluble and has a sweet taste.

Beyond anti-aging, resveratrol is also valued for its skin-brightening and soothing properties.

Some forms of resveratrol appear to be more effective than others. Resveratrol isobutyrate and resveratrol butyrate are often cited as more stable derivatives.

Research also suggests these two forms have stronger effects on Type I collagen stimulation and inflammation reduction compared to basic resveratrol.

Resveratrol is naturally unstable and can degrade when exposed to light and oxygen. Well-designed products often use stabilized derivatives, airless or opaque packaging, and supporting antioxidants to help maintain effectiveness on skin.

A note on resveratrol as a retinoid alternative:
While resveratrol offers antioxidant protection, inflammation control, and some collagen-supporting benefits, it does not replace retinoids in terms of cell turnover or acne treatment.

However, it can be a useful option for people with retinoid sensitivity or intolerance, or for those looking to support skin health without irritation.

Fun fact: Resveratrol is naturally found in grapes, peanuts, and berries, which is why it’s frequently associated with wine and grape-derived skincare ingredients.

One animal study reported tropical taurine improved barrier function and collagen signaling, while another one found oral taurine can lessen UVB-related damage. It is important to note that evidence for taurine in skincare is mostly preclinical, meaning further studies are needed.

Studies show Laminaria Japonica has antioxidant compounds. Antioxidants may help with anti-aging. Kelp also contains magnesium and zinc, making it great for calming inflammation and redness.

False daisy is used in both traditional medicines and foods throughout Southeast Asia and India.

Studies show the compounds in centella help with:

The combination of all these properties makes centella effective at soothing, hydrating, and protecting the skin.

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

Fun fact: Centella has been used as a medicine and in food for many centuries. As a medicine, it is used to treat burns, scratches, and wounds.

Studies show Madecassic Acid helps soothe the skin due to its ability to block inflammation pathways.

Some sources suggest this ingredient may cause skin sensitivity but further studies are needed.

This ingredient is an emollient, emulsifier, and penetration enhancer. As an emollient, it helps soften and hydrate skin by trapping moisture within. As an emulsifier, it prevents oil and water ingredients from separating.

Hydrogenated Lecithin can form tiny spherical structures made of phospholipid bilayers called liposomes. These liposomes are able to capture compounds inside their structure and deliver them through the skin barrier.

Because phospholipids are a natural component of our cell membranes, this ingredient is inherently compatible with skin.

A 2021 study found lecithin-based surfactants were less harsh and more tolerable comared to Sodium Lauryl Sulfate (SLS).

The scent of Rose Geranium closely resembles traditional roses.

The Cosmetic Ingredient Review (CIR) Expert Panel evaluated it (along with 22 other acryloyldimethyltaurate polymers) and concluded it's:

Due to its large molecular size, it sits on the surface of skin rather than penetrating it.

Dipropylene glycol is technically an alcohol, but it belongs to the glycol family (often considered part of the ‘good’ alcohols). This means it is hydrating and gentle on skin unlike drying solvent alcohols like denatured alcohol.

As a masking agent, Dipropylene Glycol can be used to cover the smell of other ingredients. However, it does not have a scent.

Studies show Dipropylene Glycol is considered safe to use in skincare.

Ethoxydiglycol also helps deliver other key ingredients into the skin.

This ingredient is not irritating or sensitizing. Recent research also suggests it may have skin-brightening effects through tyrosinase inhibition.

As a film former, it creates a light and flexible layer on the skin's surface. This helps lock in moisture without feeling heavy.

It's typically used at concentrations up to 1.9% in leave-on products. CIR has concluded that these ingredients are safe in cosmetics at current use levels.

Due to its large molecule size, it doesn't readily penetrate into skin and mostly just sits on the surface. A large UK-based patch test study of over 1,300 patients found that sensitization to related acrylate copolymers is rare.

It can also form a thin protective film on skin. One study found that a formula using this polymer helped slow down how quickly other ingredients (like DEET) were absorbed through skin.

A 2024 study of over 1,300 patients confirmed that sensitization to this ingredient is rare. It is also non-mutagenic and has a clean track record.

Tromethamine helps balance the pH level of a product. Normal pH level of skin is slightly acidic (~4.75-5.5). The acidity of our skin is maintained by our glands and skin biome. 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.

Oral Tromethanmine is an anti-inflammatory drug but plays the role of masking, adding fragrance, and/or balancing pH in skincare.

1,3-Propanediol, 2-amino-2-(hydroxymethyl)-

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

Studies have found adenosine may also help with wound healing.

In skincare products, Adenosine is usually derived from yeast.

Because hydrolyzed hyaluronic acid is smaller in size, it can slip past your outermost layer of skin more easily than full-sized HA.

Most formulations will combine all sizes to get the best of both worlds.

Typical usage levels range from 0.01-1%. Any percentage higher than 2% might become goopy and tacky.

A high amount of carbomer can cause pilling or balling up of products. Don't worry, most products contain 1% or less of carbomer.

This ingredient has a low sensitization risk and testing shows it does not classify as a skin irritant or sensitizer.

FOS are usually produced from sugar beets and can also be found in foods like bananas, garlic, and onions.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

On the surface, it acts as a humectant that holds water in place and reduces moisture loss for a plumper, smoother feel, while its anti-inflammatory and antioxidant properties make it a great pick for calming redness or sensitive skin

The more interesting story is underneath:

Despite its large molecular size, oat beta-glucan has been shown to penetrate the epidermis and reach the dermis by slipping between skin cells. Here, it interacts with fibroblasts and macrophages to nudge collagen synthesis and support wound repair.

A small 2005 split-face clinical study of 27 subjects found topical beta-glucan produced measurable reductions in wrinkle depth, height, and roughness after 8 weeks of use.

It is worth noting the trial was small and the penetration testing used frozen, irradiated skin so the anti-aging data is encouraging rather than definitive.

This ingredient gets along with pretty much everything and is typically used around 0.1-1%.

Fungal acne: This ingredient is not a food source for the Malassezia yeast because it is a glucose polysaccharide with no fatty acid or ester component.

You'll likely see this in many BHA products because this is the go-to solvent for salicylic acid.

This ingredient is typically used at levels between 2-20%.

Regarding fungal acne:
In 2019, this ingredient was tested against multiple Malassezia species (the yeast that causes fungal acne) and showed no growth.

One manufacturer study found their glycolipid also demonstrated sebum reduction and helped reduced oiliness after four weeks. This means it can also be great for scalp care.

Citronellol is a modified terpene. Terpenes are unsaturated hydrocarbons found in plants. They make up the primary part of essential oils.

Citronellol is not able to be absorbed into deeper layers of the skin. It has low permeability,

Citronellol is also a natural insect repellent.

Geraniol can be found in many essential oils including Rose Oil and Citronella Oil. The scent of Geraniol is often described as "rose-like". Many foods also contain Geraniol for fruit flavoring.

Geraniol can irritate the skin when exposed to air. However, irritation depends on the ability of geraniol to penetrate into the skin. In general, geraniol is not able to penetrate skin easily.

Geraniol is colorless and has low water-solubility. However, it is soluble in common organic solvents.

Like citronellol, it is a natural insect repellent.

2,6-Octadien-1-ol, 3,7-dimethyl-, (2E)-

This ingredient has a scent that is floral, spicy tropical, and citrus-like.