Cutem Laser Mask

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.

As an emollient, it can help the skin feel soft and hydrated. It is also used to reduce frizz in hair products.

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.

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.

Its headline job is hydration.

The star polysaccharide in aloe, acemannan, is a humectant that retains moisture and helps reduce trans-epidermal water loss.

Aloe also has real soothing credentials; it contains anti-inflammatory compounds like bradykinase and C-glucosyl chromone that help calm irritation and redness.

On the repair side, lab work shows that acemannan wakes up your skin's repair cells (fibroblasts), prompting them to multiply and speed up healing.

There's some human data for cosmetic benefit too: a cream containing 10% Aloe Barbadensis leaf extract improved skin hydration and elasticity in a real-use study.

Safety-wise, this ingredient is well-regarded with just one rare downside; there have been some case reports of acute eczema, contact urticaria, and dermatitis in people who applied aloe-derived ingredients topically. Those with a known aloe or Liliaceae sensitivity should patch test.

Typical use levels range widely, from under 1% up to 90%+ depending on the format and the effect you are after.

Fun fact: Purslane is a succulent with an extensive habitat. It is used in traditional Korean medicine to treat irritated skin.

Nowadays, purslane is becoming a superfood due to its highly nutritious content.

This ceramide works by slotting into gaps within the stratum corneum's lipid matrix to limit trans-epidermal water loss (TEWL) and shield the skin against external irritants.

A study with 312 patients found that using a ceramide-containing routine for 4 weeks reduced the severity of atopic dermatitis by over 61%.

Another clinical study in subjects aged 60 and older found that a ceramide body wash and moisturizer improved skin dryness and itchy skin in 15 days.

Overall, ceramides are considered non-irritating and safety tests have found little to no observable adverse effects from using this ingredient.

Ceramide NP is usually sourced from plants (like soybean or rice bran), or produced synthetically.

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).

D-panthenol is also known as dexpanthenol. Most cosmetics use dexpanthenol or a mixture of D and L-panthenol.

Panthenol is famous due to its ability to go deeper into the skin's layers. Using this ingredient has numerous pros (and no cons):

Like hyaluronic acid, panthenol is a humectant. Humectants are able to bind and hold large amounts of water to keep skin hydrated.

This ingredient works well for wound healing. It works by increasing tissue in the wound and helps close open wounds.

Once oxidized, panthenol converts to pantothenic acid. Panthothenic acid is found in all living cells.

This ingredient is also referred to as pro-vitamin B5.

Due to its antioxidant properties, trehalose may help with signs of aging. Antioxidants help fight free-radical molecules, unstable molecules that may damage your skin.

In medicine, trehalose and hyaluronic acid are used to help treat dry eyes.

Some animals, plants, and bacteria create trehalose as a source of energy to survive freeze or lack of water.

The small peptides and amino acids (including Natural Moisturizing Factor components like Hydroxyproline, Serine, and Aspartic Acid) help the surface of the skin hold onto water, feel softer, and look temporarily plumper.

This ingredient also has mild film-forming and antioxidant properties with research showing the antioxidant effect is stronger the lower the molecular weight of the peptides.

It's worth being realistic here:

Topically applied Hydrolyzed Collagen conditions the upper layers of skin rather than rebuilding the structural collagen deep in your dermis (the wrinkle-and-firmness benefits people associate with Collagen mostly come from oral supplements in studies, not topicals).

However, recent lab and skin-model work on Hydrolyzed Fish Collagen has shown promising effects on cell viability and wound healing when used as an active.

Typical concentrations range from 0.2-2%, but the percentage can go much higher in rinse-off or hair products (sometimes even above 50%).

Clinical studies on this ingredient showed no irritation, sensitization, or phototoxicity.

If you are looking for vegan collagen, it usually goes by a different INCI name like hydrolyzed soy protein. Vegan collagen is derived from yeast, bacteria, or plant sources.

The results are varied.

A study from 2021 found hydrolyzed collagen increased elasticity and improved wrinkles in 1,125 participants between age 20 and 70. Another study found increased skin thickness in participants between the ages of 45 to 59.

However, It is difficult to prove that oral collagen will end up working on your skin. Many of the studies using hydrolyzed collagen also add several vitamins and nutrients into the test mixture as well.

Further studies are needed at this time.

These compounds allow centella to dial back inflammation, encourage the skin to build and hold onto collagen, support the barrier and hydration, and bring solid antioxidant activity to protect against signs of aging.

Centella also carries a nice supporting cast of Vitamin A, vitamin C, several B vitamins, and amino acids. Put it all together and you get an ingredient that soothes, hydrates, and protects, all at once.

Most of centella's magic comes from the four big compounds (Asiaticoside, Madecassoside, Asiatic Acid, and Madecassic Acid). These are the actives doing the heavy lifting in almost every centella study.

Here is the short version of what they do in the skin:

So it is not just soothing for the sake of soothing. Centella calms the skin AND helps it rebuild.

Just FYI, not all centella on an ingredient list is the same. What you are getting actually depends on the extract:

Fun fact on the ratios: the leaves tend to be richest in Madecassoside and Asiaticoside, and lower in the two acids. The exact amounts shift with where the plant is grown and how it is processed. This means purity really does vary brand to brand.

Centella is one of the most easygoing actives out there.

It layers well with basically everything: niacinamide, hyaluronic acid, peptides, and vitamin C, and also pairs nicely with stronger actives like retinoids and exfoliating acids where it can help take the edge off irritation.

On the safety side, centella and its triterpenes are classified as weak sensitizers, meaning allergic reactions are possible but uncommon.

Patch tests at 1% and 5% came back negative in test panels, and creams at typical use levels did not cause allergic reactions across large groups of people.

But as with any new active, a patch test is still a smart move for very reactive skin.

Centella is widely used because it is effective at low percentages. For context, human safety testing found no meaningful irritation from creams containing centella extract at everyday use levels (the tested amounts were well under 1%).

The irritancy threshold in animal testing was also above 30% (so real-world formulas sit far below anything concerning).

In collagen lab studies, higher concentrations drove more collagen synthesis, so serums built around centella tend to feature it more prominently.

Bottom line: you will find centella working nicely anywhere from a fraction of a percent up to hero-ingredient levels depending on whether it is a supporting soother or the main event.

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.

Heart Leaf is rich in flavonoids such as quercetin, apigenin, and more. It also contains polysaccharides, the most common type of carbs in food.

Flavonoids have been shown to be effective antioxidants. They help neutralize free-radical molecules. Free-radical molecules are unstable molecules that may damage our skin cells and DNA. The flavonoids in Heart Leaf also help soothe the skin.

Polysaccharides are naturally found in our skin. They play a role in hydrating and repairing the top layer of skin. The polysaccharides in Heart Leaf help moisturize our skin.

Studies show decanoyl acetaldehyde, a component of Heart Leaf oil, is effective at killing bacteria.

The name 'Fish Mint' comes from the herb's natural fishy smell. Is is native to southeast Asia and used throughout the continent for traditional cooking and medicine.

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.

Due to its large molecule size, it doesn't penetrate beyond the skin's surface.

This ingredient has a solid regulatory track record; the CIR Expert Panel first concluded it was safe for use in cosmetics at concentrations up to 100% in 1997. A 2012 reassessment reaffirmed that finding. Safety studies have also found no irritation or evidence of toxicity.

A 2019 study did find this ingredient to grow Malassezia, so this ingredient may not be fungal acne safe.

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.

It also needs to be neutralized to actually thicken, and because it is a large molecule, it doesn't really penetrate the skin barrier.

Allergy-wise, the risk is very low. Clinical studies show carbomers have low potential for skin irritation/sensitization even at concentrations up to 100%.

A 2024 UK study patch-tested 1,302 patients and found true allergy to the parent group of carbomer to be rare with no confirmed relevant reactions.

Using high concentrations of Potassium Hydroxide have shown to irritate the skin.

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

Chlorphenesin is soluble in both water and glycerin.

Studies show Chlorphenesin is easily absorbed by our skin. You should speak with a skincare professional if you have concerns about using Chlorphenesin.