Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Erno Laszlo Firmarine Cleansing Oil Versus PCA Skin BPO 5% Cleanser

Erno Laszlo Firmarine Cleansing Oil Versus PCA Skin BPO 5% Cleanser This benzoyl peroxide foaming cleanser is formulated around Benzoyl Peroxide to clear breakouts and help reduce acne-causing bacteria. What's inside Key Ingredients Benefits Concerns Ingredien

Erno Laszlo Firmarine Cleansing Oil Versus PCA Skin BPO 5% Cleanser

This benzoyl peroxide foaming cleanser is formulated around Benzoyl Peroxide to clear breakouts and help reduce acne-causing bacteria.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Hydrogenated Polyisobutene

Simmondsia Chinensis Seed Oil

Disodium Laureth Sulfosuccinate

Sodium C14-16 Olefin Sulfonate

Cocamidopropyl Betaine

Glycerin

Sodium Lauryl Sulfoacetate

Olea Europaea Fruit Oil

Tocopheryl Acetate

Spirulina Maxima Extract

Cucumis Sativus Fruit Extract

Camellia Oleifera Leaf Extract

Sea Water

Butylene Glycol

Disodium EDTA

Sodium Chloride

Sodium Sulfate

Chlorphenesin

Caprylyl Glycol

Hexylene Glycol

Phenoxyethanol

Parfum

CI 42090

Water, Hydrogenated Polyisobutene, Simmondsia Chinensis Seed Oil, Disodium Laureth Sulfosuccinate, Sodium C14-16 Olefin Sulfonate, Cocamidopropyl Betaine, Glycerin, Sodium Lauryl Sulfoacetate, Olea Europaea Fruit Oil, Tocopheryl Acetate, Spirulina Maxima Extract, Cucumis Sativus Fruit Extract, Camellia Oleifera Leaf Extract, Sea Water, Butylene Glycol, Disodium EDTA, Sodium Chloride, Sodium Sulfate, Chlorphenesin, Caprylyl Glycol, Hexylene Glycol, Phenoxyethanol, Parfum, CI 42090

Benzoyl Peroxide 5%

Gluconolactone

Aminomethyl Propanol

Acrylates/C10-30 Alkyl Acrylate Crosspolymer

Polyacrylate-13

Citrus Grandis Peel Oil

Polyisobutene

Ethylhexylglycerin

Allantoin

Triticum Vulgare Germ Oil

Aloe Barbadensis Leaf Juice

Panthenol

Sodium PCA

Polysorbate 20

Phytic Acid

Algae Extract

Anthemis Nobilis Flower Extract

Arnica Montana Flower Extract

Vitis Vinifera Seed Extract

Benzoyl Peroxide 5%, Water, Gluconolactone, Sodium C14-16 Olefin Sulfonate, Aminomethyl Propanol, Glycerin, Cocamidopropyl Betaine, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Phenoxyethanol, Polyacrylate-13, Citrus Grandis Peel Oil, Polyisobutene, Caprylyl Glycol, Ethylhexylglycerin, Hexylene Glycol, Allantoin, Simmondsia Chinensis Seed Oil, Tocopheryl Acetate, Triticum Vulgare Germ Oil, Aloe Barbadensis Leaf Juice, Panthenol, Sodium PCA, Polysorbate 20, Butylene Glycol, Phytic Acid, Algae Extract, Anthemis Nobilis Flower Extract, Arnica Montana Flower Extract, Cucumis Sativus Fruit Extract, Vitis Vinifera Seed Extract

Alternatives

Ingredients Explained

These ingredients are found in both products.

Ingredients higher up in an ingredient list are typically present in a larger amount.

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

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.

Caprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.

Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.

Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).

Cocamidopropyl Betaine is a fatty acid created by mixing similar compounds in coconut oil and dimethylaminopropylamine, a compound with two amino groups.

This ingredient is a surfactant and cleanser. It helps gather the dirt, pollutants, and other impurities in your skin to be washed away. It also helps thicken a product and make the texture more creamy.

Being created from coconut oil means Cocamidopropyl Betaine is hydrating for the skin.

While Cocamidopropyl Betaine was believed to be an allergen, a study from 2012 disproved this. It found two compounds in unpure Cocamidopropyl Betaine to be the irritants: aminoamide and 3-dimethylaminopropylamine. High-grade and pure Cocamidopropyl Betaine did not induce allergic reactions during this study.

This extract comes from cucumber. Cucumbers are mostly made up of water (95%), and the other 5% is composed of: vitamin C, caffeic acid, fatty acids, amino acids, and other minerals.

Cucumbers have anti-inflammatory, barrier repair, and hydrating properties.

They contain shikimate dehydrigenase, an enzyme shown to help reduce inflammation and soothe the skin.

The amino acids found in cucumbers help nourish our skin's natural acid mantle (it's an important part of our skin barrier). This slightly acidic film acts as a barrier to protect us from bacteria, viruses, and other contaminants.

Unless you have an allergy to cucumbers, this is generally a non-irritating ingredient.

Fun fact: Cucumis Sativus is native to South Asia and can now be found on every continent.

Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.

Topically, glycerin does several things at once:

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.

Hexylene Glycol is a multitasker ingredient that works as a solvent, humectant, emulsifier, viscosity reducer, and preservative booster.

It is able to dissolve both water and oil-soluble ingredients to stabilize tricky actives and make products spread more easily.

As a humectant, it pulls water into the skin. But it's a pretty minor moisturizing ingredient compared to other humectants, like glycerin.

Interestingly, it can act as a mild penetration enhancer. One in vitro study on human skin found a 12% concentration upped the absorption of mometasone furoate (a medicinal ingredient used to treat inflammatory skin conditions) up to 7%.

This ingredient is typically used at levels of 0.1-10% depending on the role it's playing.

A patch test study on eczema patients didn't find a significant increase in irritation versus the control group, but the potential for irritation rises at higher concentrations.

Phenoxyethanol is one of the most widely used preservatives in skincare (and for good reason!).

It has a large spectrum of antimicrobial activity and especially effective bacteria, yeast, and mold while only having a weak effect on your skin's natural microbiome.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

Jojoba oil is one of the most well-studied plant-derived ingredients in cosmetics. It is an emollient with a special structure.

Because it is made up of 97-98% wax esters, it closely mirrors the linear monoesters found in human sebum. This makes it skin compatible, non-greasy, and lightweight.

Unlike other plant oils, jojoba wax doesn't easily penetrate skin. It mostly works in the uppermost layers as an emollient. This just means it forms a light barrier on the skin to help retain moisture.

Formulations with jojoba esters up to 90% reduced transepidermal water loss (TEWL) and increased barrier recovery by 81% (outperforming bisabolol at 47%).

Besides barrier support, the science also suggests jojoba to have anti-inflammatory effects and potential applications for skin infections, aging, and wound healing.

Fun fact: Indigenous cultures have used jojoba as a moisturizer and to help treat burns for centuries.

Fungal acne: The Malassezia yeast is known to metabolize fatty acids in the C11-24 range and jojoba's dominant fatty acid components fall into this range. This ingredient may not be fungal acne safe.

Sodium C14-16 Olefin Sulfonate is a surfactant that helps water and oil mix so that dirt, sweat, sebum, and sunscreen can rinse away easily. It's not technically a sulfate, but behaves similarly in formulas.

What it does:

Sodium C14-16 Olefin Sulfonate is a strong cleansing surfactant and is much stronger than many mild cleansers. Because it works deeply, it can disrupt the skin's barrier. This can lead to dryness or irritation for those with sensitive skin.

Compared to gentler surfactants, it's effective but more likely to dry or irritate if not balanced with soothing ingredients.

CIR considers sodium α-olefin sulfonates (including C14-16) to be safe for use in rinse-off products when properly formulated. It is poorly absorbed through normal skin but absorption increases if the skin barrier is already damaged.

Tocopheryl Acetate is a stable, shelf-friendly form of vitamin E.

Formulators love it because plain vitamin E oxidizes quickly once it hits air. This acetate version stays stable and resists going off, helping to extend a product's shelf life.

It's actually inactive on its own and works like a slow-release "storage" form; the enzymes in your skin called esterases gradually convert it into active vitamin E over time.

One in vivo study showed 5% of the acetate in the living layer of the epidermis converted to vitamin E after 5 days of application. This study also found the skin gained protection against UV damage even though the conversion was slow and small.

Once converted, vitamin E acts as a skin's main fat-soluble antioxidant that fights free radicals to protect skin from damage.

Topical vitamin E generally boosts the skin's photoprotection, and it reduced UV-damage in animal models.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

Overall, it has a pretty solid safety profile and has been found to be non-irritating and non-comedogenic. Allergic reactions may happen but stay rare due to how widely the ingredient gets used.

The concentration will vary depending on the formula; industry data shows 0.1% in baby lotions, 3% in lipsticks, and 5% in foot powders. You can also find this ingredient at 100% in a pure vitamin E oil.

Most leave-on skincare keeps it at the lower end, often between 0.5-1%.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!

Similar Comparisons

The reference edit

Ingredients, questions
& further reading.

Connected source records selected through this article’s public topic index.

01

Formula cabinet

Ingredients & structured notes

Ingredient index

Ingredients Explained

  1. 01These ingredients are found in both products.
  2. 02Ingredients higher up in an ingredient list are typically present in a larger amount.
  3. 03Caprylic/Capric Triglyceride (aka MCT Oil) is a lightweight emollient, solvent, and texture enhancer. It is considered a skin-softener by helping to prevent moisture loss.
  4. 04Though it behaves like an oil, it is not technically one due to its chemical composition. One perk of this ingredient is that it is very stable, resistant to oxidation, and unlikely to go rancid.
  5. 05In practice, that translates to a long shelf life and a consistently elegant skin feel.
  6. 06While there is an assumption Caprylic Triglyceride can clog pores due to it being derived from coconut oil, there is no research supporting this. Just patch test if you have concerns.
  7. 07Fractionated coconut oil and MCT Oil are both listed as Caprylic/Capric Triglyceride according to INCI. This is because INCI names are based on the ingredient’s final chemical composition and not its marketing name or source.
  8. 08This ingredient is treated as the gold standard fungal acne safe oil. Even though it is coconut derived, the problematic lauric acid is stripped out.
  9. 09This leaves just caprylic (C8) and capric (C10) acid. These chain lengths actually trend antifungal; a 2020 study found caprylic acid was enough to disrupt Malassezia furfur cell membrane, with a caprylic acid derivative damaging membrane structures…
  10. 10Caprylyl Glycol is a humectant, skin conditioner, emollient, and preservative booster derived from either caprylic acid or synthetically created.
  11. 11Typical use levels vary from 0.3-1% as a preservative booster and go up to 2% to condition skin.
  12. 12Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).
  13. 13Cetearyl alcohol is a waxy mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is an emollient and emulsifier.
  14. 14Despite having "alcohol" in its name, it has nothing to do with drying solvent alcohols; the FDA also allows "alcohol-free" products to contain fatty alcohols like this ingredient.
  15. 15It plays several roles in a formula:
  16. 16Typical use levels for this ingredient sit around 1-10% and the Cosmetic Ingredient Review Expert Panel has affirmed safety at concentrations up to 25% in leave-on products.
  17. 17Multiple assessments have found it to be non-irritating and non-sensitizing to most people.
  18. 18However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.
  19. 19Cetearyl alcohol has a comedogenic rating of 2 and irritancy rating of 1. Both of these numbers come from the 1989 study that used rabbit ears; a "2" means mildly comedogenic and a "1" means low irritancy.
  20. 20Here's the catch: rabbit skin is more sensitive than human skin and throws a lot of false positives. A 1996 reappraisal found that ingredients rated 1-2 in the rabbit ear tests are generally safe for humans.
Source · skinsort.com
02

Product index

Related product references

Product

PCA Skin Clinicalm™ 1%

PCA Skin Clinicalm™ 1% PCA Skin Clinicalm™ 1% ingredients explained: Hydrocortisone (1%), Water, Glycerin, Caprylic/Capric Triglyceride, Alcohol Denat, Cetearyl Olivate, Squalane, Olea Euro…

Source: incidecoder.comView reference →

Product

PCA Skin Rebalance (Discontinued)

PCA Skin Rebalance (Discontinued) PCA Skin Rebalance ingredients explained: Water/Aqua/Eau, Aloe Barbadensis Leaf Juice, Ethylhexyl Isononanoate, Glycereth-26, Butylene Glycol, Sodium Hyalu…

Source: incidecoder.comView reference →

Product

PCA Skin Collagen Hydrator

PCA Skin Collagen Hydrator PCA Skin Collagen Hydrator ingredients explained: Water/Aqua/Eau, Glyceryl Stearate, Glycerin, C12-15 Alkyl Benzoate, Cetearyl Alcohol, Isopropyl Palmitate, Cyclo…

Source: incidecoder.comView reference →
03

Comparison edit

Read side by side