Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Paula's Choice RESIST Daily Smoothing Treatment With 5% AHA Versus Philosophy Clear Days Ahead Fast-Acting Salicylic Acid Acne Spot Treatment

Paula's Choice RESIST Daily Smoothing Treatment With 5% AHA Versus Philosophy Clear Days Ahead Fast-Acting Salicylic Acid Acne Spot Treatment This smoothing exfoliator is formulated around Glycolic Acid and Palmitoyl Hexapeptide-12 to refine skin texture and s

Paula's Choice RESIST Daily Smoothing Treatment With 5% AHA Versus Philosophy Clear Days Ahead Fast-Acting Salicylic Acid Acne Spot Treatment

This smoothing exfoliator is formulated around Glycolic Acid and Palmitoyl Hexapeptide-12 to refine skin texture and soften the look of wrinkles.

This acne treatment is formulated around Salicylic Acid and Glycolic Acid to clear breakouts and refine the look of pores.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Glycolic Acid

Cetyl Alcohol

Butylene Glycol

Polyacrylamide

Dimethicone

PPG-14 Butyl Ether

Palmitoyl Hexapeptide-12

Ceramide Ng

Tetrahydrodiferuloylmethane

Tetrahydrodemethoxydiferuloylmethane

Tetrahydrobisdemethoxydiferuloylmethane

Epigallocatechin Gallate

Salicylic Acid

Disodium Lauriminodipropionate Tocopheryl Phosphates

PEG-10 Phytosterol

Vanilla Planifolia Fruit Extract

Bisabolol

Allantoin

Cyclopentasiloxane

Cyclohexasiloxane

Dimethiconol

Tribehenin

C12-15 Alkyl Benzoate

PEG-40 Stearate

Sorbitan Stearate

Pvm/Ma Decadiene Crosspolymer

Disodium EDTA

C13-14 Isoparaffin

Laureth-7

Sodium Hydroxide

Caprylyl Glycol

Caprylic/Capric Triglyceride

Hexylene Glycol

Ethylhexylglycerin

Phenoxyethanol

Water, Glycolic Acid, Cetyl Alcohol, Butylene Glycol, Polyacrylamide, Dimethicone, PPG-14 Butyl Ether, Palmitoyl Hexapeptide-12, Ceramide Ng, Tetrahydrodiferuloylmethane, Tetrahydrodemethoxydiferuloylmethane, Tetrahydrobisdemethoxydiferuloylmethane, Epigallocatechin Gallate, Salicylic Acid, Disodium Lauriminodipropionate Tocopheryl Phosphates, PEG-10 Phytosterol, Vanilla Planifolia Fruit Extract, Bisabolol, Allantoin, Cyclopentasiloxane, Cyclohexasiloxane, Dimethiconol, Tribehenin, C12-15 Alkyl Benzoate, PEG-40 Stearate, Sorbitan Stearate, Pvm/Ma Decadiene Crosspolymer, Disodium EDTA, C13-14 Isoparaffin, Laureth-7, Sodium Hydroxide, Caprylyl Glycol, Caprylic/Capric Triglyceride, Hexylene Glycol, Ethylhexylglycerin, Phenoxyethanol

Salicylic Acid 2%

Isododecane

Alcohol Denat.

Polysilicone-11

Glycereth-7 Trimethyl Ether

Propanediol

Isopropyl Myristate

Coco-Caprylate/Caprate

Ethoxydiglycol

Sodium Acrylates Copolymer

Trimethylpentanediol/Adipic Acid Copolymer

Decyl Glucoside

Lecithin

Lauryl Glucoside

Laureth-12

Farnesol

Salicylic Acid 2%, Water, Dimethicone, Isododecane, Alcohol Denat., Polysilicone-11, Glycereth-7 Trimethyl Ether, Propanediol, Glycolic Acid, Polyacrylamide, Isopropyl Myristate, Coco-Caprylate/Caprate, Ethoxydiglycol, C13-14 Isoparaffin, Sodium Acrylates Copolymer, Trimethylpentanediol/Adipic Acid Copolymer, Sodium Hydroxide, Butylene Glycol, Laureth-7, Bisabolol, Decyl Glucoside, Lecithin, Lauryl Glucoside, Disodium EDTA, Laureth-12, Phenoxyethanol, Caprylyl Glycol, Hexylene Glycol, Ethylhexylglycerin, Farnesol

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Bisabolol is a gentle skin conditioner, antioxidant, and soothing ingredient.

It's primary claim to fame is soothing and research shows topically applied bisabolol can quiet the chemical messengers that cause your skin to become inflamed, helping to sooth any irritation.

A clinical study found that applying 0.5% bisabolol daily for 8 weeks produced an average 9% decrease in skin pigmentation. Researchers found it can also suppress the process that leads to excess melanin production in skin.

In vitro studies found that bisabolol combined with propylene glycol significantly increased skin permeability by increasing lipid fluidity in the stratum corneum.

You'll likely see use concentrations quite low, usually 0.1-0.2%.

Overall, this is a well-tolerated ingredient that works well in formulas designed for sensitive, reactive, or post-procedure skin.

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.

C13-14 Isoparaffin is a synthetic emollient, solvent, and thickening agent. It helps soften skin and improves spreadability without leaving a greasy residue.

This ingredient has been found to be non-sensitizing and safe for use in cosmetics.

Two things floating around online that cause fear-mongering:

There's one scary-sounding study related to kidney tumors in male rats; this depends on a protein called alpha-2u-globulin that binds the ingredient and clogs up kidney cells. Female rats barely make this protein, and humans don't make it at all so this effect cannot happen to us. Regulatory bodies have states this rat-only pathway shouldn't be used to judge human risk.

The other thing you'll see is 1,4-dioxane being a trace byproduct that can form during manufacturing of petroleum-derived ingredients. This is a real, but heavily managed/monitored issue. This byproduct is removed through purification steps before the ingredients goes into the formula. Regulatory bodies also actively monitor residual levels for safety.

One last thing to note: this ingredient is a pure hydrocarbon with no fatty-acid or ester chains for Malassezia to feed on, so it's considered fungal acne safe.

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).

Dimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.

What it does:

Dimethicone comes in different viscosities:

Depending on the viscosity, dimethicone has different properties.

Ingredients lists don't always show which type is used, so we recommend reaching out to the brand if you have questions about the viscosity.

This ingredient is unlikely to cause irritation because it does not get absorbed into skin. However, people with silicone allergies should be careful about using this ingredient.

Note: Dimethicone may contribute to pilling. This is because it is not oil or water soluble, so pilling may occur when layered with products. When mixed with heavy oils in a formula, the outcome is also quite greasy.

Disodium EDTA is a chelating agent. It grabs onto and deactivates metal ions that sneak into your products from water, packaging, or air.

This ingredient mainly works behind the scenes and helps with:

On top of that, this ingredient can counteract the effects of hard water by binding to the minerals in it.

One thing worth knowing is that Disodium EDTA has been shown to be a mild penetration enhancer. It can help other ingredients absorb into skin more effectively which can be a double-edged sword (great for actives, but can also make the active too strong if you have sensitive skin).

Clinical patch testing showed no significant skin irritation at typical use concentrations and minimal dermal absorption.

You'll most likely see this ingredient near the end of an ingredient list. It's typically found in concentrations less than 1%.

Ethylhexylglycerin is created from glycerin. It is a multitasker ingredient that:

The CIR Expert Panel found minimal skin absorption or sensitization of any kind in a safety assessment. Though this ingredient is considered well-tolerated, a small number of cases of allergic dermatitis have been published since 2002. Just be sure to patch test if you are unsure.

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

Glycolic Acid is arguably the most famous alpha hydroxy acid (AHA) with tons of research backing its benefits.

It is found naturally in sugar cane but the form used in skincare is usually synthetic for purity and stability.

Glycolic acid removes the top layer of dead skin cells to allow newer and fresher ones to emerge.

AHAs work by breaking down the structural “glue” that holds old skin cells in place. When that buildup is gone, your skin can renew itself more efficiently.

Research also shows glycolic acid stimulates collagen production, helping to firm and thicken the skin over time. This is one of its biggest advantages over other AHAs.

Overall, glycolic acid helps with:

Fun fact: Glycolic acid boosts skin hydration by helping it produce molecules that increase hyaluronic acid naturally.

To work best, glycolic acid products should have a pH between 3-4 (that’s where exfoliation is most effective but still gentle on skin).

The pH and concentration of a product are key to its effectiveness:

It is normal to feel a slight stinging sensation when using glycolic acid. This usually fades as your skin adjusts.

Because glycolic acid has the smallest molecular size in the AHA family, it can penetrate deeper, which enhances its effectiveness but also makes it more likely to irritate sensitive skin.

If your skin is very sensitive or prone to rosacea, glycolic acid may be too strong; in that case, try milder options like lactic acid or a PHA instead.

Recent studies suggest glycolic acid might even help protect against UV damage. But don’t skip sunscreen! Freshly exfoliated skin is more sensitive to the sun.

Glycolic acid is a skincare superstar. It smooths, brightens, hydrates, and firms the skin. Unless you’re highly sensitive, it’s well worth adding to your routine.

Read more about some other popular AHA's here:

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.

Laureth-7 is created by the ethoxylation of lauryl alcohol using ethylene oxide. Lauryl alcohol is a fatty alcohol with hydrating properties.

This ingredient is an emulsifier and cleansing ingredient. As an emulsifier, it is used to prevent ingredients from separating. It also helps cleanse the skin by gathering dirt, oil, and pollutants to be rinsed away.

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.

Polyacrylamide is a synthetic polymer. It is used to stabilize products and bind ingredients. When hydrated, Polyacrylamide forms a soft gel.

Polyacrylamide is low-toxicity. If source properly, it is deemed safe to use in cosmetics.

It should be noted the precursor to Polyacrylamide is acrylamide. Acrylamide is a carcinogen. Most reputable sources of Polyacrylamide will screen for residual acrylamide to make sure the count is in a safe range. Acrylamide is not able to be absorbed through the skin.

We recommend speaking with a professional if you have concerns.

Salicylic Acid (also known as beta hydroxy acid or BHA) is a well-known ingredient for treating skin that struggles with acne and clogged pores. It exfoliates both the skin's surface and deep within the pores to help clear out buildup, control oil, and reduce inflammation.

Unlike AHAs (alpha hydroxy acids), salicylic acid is oil-soluble. This allows it to penetrate into pores which makes it especially effective for treating blackheads and preventing future breakouts.

Salicylic acid is also known for its soothing properties. It has a similar structure to aspirin and can calm inflamed or irritated skin, making it a good option for acne-prone skin that is also sensitive.

Concentrations of 0.5-2% are recognized by the U.S. FDA as an over-the-counter topical acne product.

It can cause irritation and/or dryness if one's skin already has a compromised moisture barrier, so it's best to focus on repairing that before introducing this ingredient into your routine.

While salicylic acid does not increase sun sensitivity, it’s still important to wear sunscreen daily to protect your skin.

If you are looking for the ingredient called BHA or Butylated Hydroxyanisole, click here.

Sodium Hydroxide is also known as lye or caustic soda. It is used to adjust the pH of products; many ingredients require a specific pH to be effective.

In small amounts, sodium hydroxide is considered safe to use. However, large amounts may cause chemical burns due to its high alkaline.

Your skin has a natural pH and acid mantle. This acid mantle helps prevent harmful bacteria from breaking through. The acid mantle also helps keep your skin hydrated.

"Alkaline" refers to a high pH level. A low pH level would be considered acidic.

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. 03Ammonium Acryloyldimethyltaurate/Vp Copolymer is a synthetically created polymer. It's used as a film-forming agent and used to thicken the consistency of products.
  4. 04Think of it as a supportive ingredient that helps your gel-creams feel silky, "cloud cream-like", and spread evenly without being greasy.
  5. 05The Cosmetic Ingredient Review (CIR) Expert Panel evaluated it (along with 22 other acryloyldimethyltaurate polymers) and concluded it's:
  6. 06Due to its large molecular size, it sits on the surface of skin rather than penetrating it.
  7. 07Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:
  8. 08Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
  9. 09Though 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.
  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. 13Cetyl Alcohol is a fatty alcohol. Fatty Alcohols are most often used as an emollient or to thicken a product.
  14. 14Its main roles are:
  15. 15Though it has "alcohol" in the name, it is not related to denatured alcohol or ethyl alcohol.
  16. 16The FDA allows products labeled "alcohol-free" to have fatty alcohols.
  17. 17This ingredient may not be fungal acne safe. It is a primary fatty alcohol with a chain length above 12 carbons. A study from 2019 show Malassezia can feed on fatty alcohols in this range, so it may trigger fungal acne in those prone to it.
  18. 18Dimethicone is a type of synthetic silicone created from natural materials such as quartz. It is also known as polydimethylsiloxane.
  19. 19What it does:
  20. 20Dimethicone comes in different viscosities:
Source · skinsort.com
02

Product index

Related product references

03

Comparison edit

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