Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

The INKEY List Niacinamide Oil Control Serum Versus Paula's Choice Discoloration Repair Serum

The INKEY List Niacinamide Oil Control Serum Versus Paula's Choice Discoloration Repair Serum This oil-control serum is formulated around Niacinamide to balance excess oil and refine the look of pores. This brightening serum is formulated around Niacinamide an

The INKEY List Niacinamide Oil Control Serum Versus Paula's Choice Discoloration Repair Serum

This oil-control serum is formulated around Niacinamide to balance excess oil and refine the look of pores.

This brightening serum is formulated around Niacinamide and Tranexamic Acid to fade the look of dark spots and brighten dull-looking skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Niacinamide

Glycerin

Propanediol

Butylene Glycol

Phenoxyethanol

Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer

Hydroxyethylcellulose

Phospholipids

Squalane

Xanthan Gum

Glycine Soja Oil

Allantoin

Sodium Phytate

Polysorbate 60

Panthenol

Glycolipids

Leuconostoc/Radish Root Ferment Filtrate

Sorbitan Isostearate

Glycine Soja Sterols

Citric Acid

Hyaluronic Acid

Disodium Phosphate

Sodium Phosphate

Water, Niacinamide, Glycerin, Propanediol, Butylene Glycol, Phenoxyethanol, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Hydroxyethylcellulose, Phospholipids, Squalane, Xanthan Gum, Glycine Soja Oil, Allantoin, Sodium Phytate, Polysorbate 60, Panthenol, Glycolipids, Leuconostoc/Radish Root Ferment Filtrate, Sorbitan Isostearate, Glycine Soja Sterols, Citric Acid, Hyaluronic Acid, Disodium Phosphate, Sodium Phosphate

Tranexamic Acid

C13-15 Alkane

Caprylic/Capric Triglyceride

Dicaprylyl Carbonate

Ethyl Macadamiate

Behenyl Alcohol

Glyceryl Stearate

Silybum Marianum Seed Oil

Tocopherol

Lactobacillus/Coconut Fruit Juice Ferment Filtrate

Lecithin

Bakuchiol

Caprylyl Glycol

Hydrogenated Lecithin

Hexylene Glycol

Boerhavia Diffusa Root Extract

Malic Acid

Ethylhexylglycerin

Water, Niacinamide, Glycerin, Tranexamic Acid, C13-15 Alkane, Caprylic/Capric Triglyceride, Dicaprylyl Carbonate, Ethyl Macadamiate, Behenyl Alcohol, Glyceryl Stearate, Butylene Glycol, Silybum Marianum Seed Oil, Tocopherol, Lactobacillus/Coconut Fruit Juice Ferment Filtrate, Lecithin, Bakuchiol, Xanthan Gum, Caprylyl Glycol, Hydrogenated Lecithin, Allantoin, Glycine Soja Oil, Hexylene Glycol, Boerhavia Diffusa Root Extract, Glycine Soja Sterols, Citric Acid, Sodium Phytate, Malic Acid, Phenoxyethanol, Ethylhexylglycerin

Reviews

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Allantoin is a soothing ingredient known for its protective and moisturizing properties; it's basically a quiet workhorse ingredient you can find in a huge range of cosmetics.

Though it can be derived from the comfrey plant, allantoin is produced synthetically for cosmetic products to ensure purity.

Research shows it can encourage your skin cells to turn over and renew by stimulating keratinocyte and fibroblast proliferation.

It also has mild keratolytic properties to help loosen and shed dead skin cells without being harsh.

Studies also suggest allantoin can help calm inflammation by dialing down some of the chemical signals your skin sends out when it is irritated.

This ingredient is typically used in the 0.1-0.5% range, and the FDA recognizes it as a skin protectant in OTC products up to 2%.

Overall, allantoin is a wonderful addition to most routines; it is stable across a wide pH range (~4-8), works well with other ingredients, and is considered non-sensitizing/non-irritating.

Fun fact: Allantoin is naturally occurring in comfrey root, beets, chamomile, and wheat sprouts. Our bodies even produce it as a byproduct of uric acid metabolism.

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.

Citric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.

Like other AHAs, citric acid can exfoliate skin by breaking down the bonds that hold dead skin cells together. This helps reveal smoother and brighter skin underneath.

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.

Rosacea skin has a lower threshold for acids generally, with 62.5% of rosacea subjects in one study reacting to lactic acid in a sting test. This is why we mark citric acid as a potential rosacea trigger.

However, this ingredient shows up as a pH adjuster or chelator at roughly 0.1-1% in many products. These low levels are unlikely to be an issue for rosacea skin and becomes a potential trigger at exfoliating concentrations (20%). Because everybody's skin is unique, we recommend a patch test if you are unsure.

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.

Glycine Soja Oil is a plant-derived oil from soybean seeds. Like other oils, it is rich in essential fatty acids (mostly linoleic and oleic) that support skin hydration and barrier function.

The fatty acids are able to integrate into the lipid matrix of the stratum corneum to help soften skin and reduce water loss.

On top of that, soybean oil is rich in vitamins like vitamin E, a potent antioxidant.

Research on soybean's active components also point to anti-inflammatory, collagen-stimulating, antioxidant activity, and protection against UV-induced oxidative damage.

Most of this research applies to the broader soybean plant and not just the oil fraction alone.

This ingredient may not be fungal acne safe due to the oleic acid content.

Glycine Soja Sterols are plant-derived fatty alcohols (phytosterols) from soybean.

You can think of them like the plant world's version of cholesterol; they're structurally similar enough to slot into your skin's lipid barrier and help it do its job.

Phytosterols aid skin barrier recovery by traveling deeper into the skin rather than just sitting on top of it. Once inside, they reduce transepidermal water loss (TEWL) and keep skin feeling soft / supple.

Research on phytosterols in keratinocyte and macrophase models has shown meaningful inhibition of pro-inflammatory mediators. This supports their reputation as a calming ingredient for reactive or sensitive skin.

Subjects with soy allergies did not show a reaction to phytosterols in safety tests, but it wouldn't hurt to patch test if you do have a soy allergy.

Fungal acne: Malassezia uses sterols to build its own cell walls so there's a theoretical concern that it could also make use of sterol ingredients in skincare.

Though no study has actually proven this happens with topical products, we err on the side of caution and list this ingredient as not safe for fungal acne. However, it may not be a trigger for everyone.

Niacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.

And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.

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.

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.

Sodium Phytate is the synthetic salt form of phytic acid. Phytic acid is an antioxidant and can be found in plant seeds.

Sodium Phytate is a chelating agent. Chelating agents help prevent metals from binding to water. This helps stabilize the ingredients and the product.

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!

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.

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.

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. 03Cetearyl alcohol is a waxy mixture of two fatty alcohols: cetyl alcohol and stearyl alcohol. It is an emollient and emulsifier.
  4. 04Despite 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.
  5. 05It plays several roles in a formula:
  6. 06Typical 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.
  7. 07Multiple assessments have found it to be non-irritating and non-sensitizing to most people.
  8. 08However, there have been some cases of allergic contact dermatitis in patients with chronically compromised skin barriers.
  9. 09Cetearyl 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.
  10. 10Here'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.
  11. 11Remember comedogenic ratings are unable to assess the entire formula of a product or how it will react on your skin. Just be sure to patch test if you are unsure about certain ingredients.
  12. 12This ingredient is not fungal acne safe. Cetearyl alcohol is a fatty alcohol with chain lengths that fall within the range that Malassezia can metabolize.
  13. 13A 2019 study has also observed Malassezia growth in the presence of this ingredient, confirming it to be not-fungal acne safe.
  14. 14Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.
  15. 15Topically, glycerin does several things at once:
  16. 16Your 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.
  17. 17Aquaporin-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.
  18. 18This 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.
  19. 19Just know very high concentrations (>40%) can feel tacky in low humidity.
  20. 20Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.
Source · skinsort.com
02

Product index

Related product references

Product

The Inkey List Vitamin C Serum

The Inkey List Vitamin C Serum The Inkey List Vitamin C Serum ingredients explained: Dimethicone, Ascorbic Acid, Polysilicone-11, Peg-10 Dimethicone Show all ingredients by function Dimethi…

Source: incidecoder.comView reference →
03

Comparison edit

Read side by side