Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Paula's Choice 10% Azelaic Acid Booster Versus The INKEY List Polyhydroxy Acid (PHA) Toner

Paula's Choice 10% Azelaic Acid Booster Versus The INKEY List Polyhydroxy Acid (PHA) Toner This calming treatment is formulated around Azelaic Acid and Salicylic Acid to calm redness and fade the look of dark spots. This smoothing toner is formulated around Gl

By Peptide Skincare & Beauty Editorial TeamPublished

Paula's Choice 10% Azelaic Acid Booster Versus The INKEY List Polyhydroxy Acid (PHA) Toner

This calming treatment is formulated around Azelaic Acid and Salicylic Acid to calm redness and fade the look of dark spots.

This smoothing toner is formulated around Gluconolactone and Niacinamide to refine skin texture and brighten dull-looking skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Azelaic Acid

C12-15 Alkyl Benzoate

Caprylic/Capric Triglyceride

Methyl Glucose Sesquistearate

Glycerin

Cetearyl Alcohol

Glyceryl Stearate

Dimethicone

Salicylic Acid

Adenosine

Glycyrrhiza Glabra Root Extract

Boerhavia Diffusa Root Extract

Allantoin

Bisabolol

Cyclopentasiloxane

Xanthan Gum

Sclerotium Gum

Propanediol

Butylene Glycol

Phenoxyethanol

Water, Azelaic Acid, C12-15 Alkyl Benzoate, Caprylic/Capric Triglyceride, Methyl Glucose Sesquistearate, Glycerin, Cetearyl Alcohol, Glyceryl Stearate, Dimethicone, Salicylic Acid, Adenosine, Glycyrrhiza Glabra Root Extract, Boerhavia Diffusa Root Extract, Allantoin, Bisabolol, Cyclopentasiloxane, Xanthan Gum, Sclerotium Gum, Propanediol, Butylene Glycol, Phenoxyethanol

Gluconolactone 3%

Niacinamide 3%

Pentylene Glycol

Aloe Barbadensis Leaf Juice

Potassium Sorbate

Sodium Benzoate

PPG-26-Buteth-26

PEG-40 Hydrogenated Castor Oil

1,2-Hexanediol

Caprylyl Glycol

Ethylhexylglycerin

Citric Acid

Sodium Hydroxide

Water, Propanediol, Gluconolactone 3%, Niacinamide 3%, Pentylene Glycol, Glycerin, Aloe Barbadensis Leaf Juice, Potassium Sorbate, Sodium Benzoate, PPG-26-Buteth-26, PEG-40 Hydrogenated Castor Oil, 1,2-Hexanediol, Caprylyl Glycol, Ethylhexylglycerin, Citric Acid, Sodium Hydroxide

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.

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.

Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin.

It’s often used to:

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.

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. 03Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:
  4. 04Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.
  5. 05Though 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.
  6. 06Citric Acid is an alpha hydroxy acid (AHA) naturally found in citrus fruits like oranges, lemons, and limes.
  7. 07Like 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.
  8. 08However, this exfoliating effect only happens at high concentrations (20%) which can be hard to find in cosmetic products.
  9. 09Due 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.
  10. 10In skincare formulas, citric acid can:
  11. 11While it can provide some skin benefits, research shows lactic acid and glycolic acid are generally more effective and less irritating exfoliants.
  12. 12Most 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.
  13. 13Rosacea 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.
  14. 14However, 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…
  15. 15Glycerin (or glycerol) is a compound naturally found in your skin. It's a powerhouse humectant that pulls water into the stratum corneum.
  16. 16Topically, glycerin does several things at once:
  17. 17Your 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.
  18. 18Aquaporin-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.
  19. 19This 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.
  20. 20Just know very high concentrations (>40%) can feel tacky in low humidity.
Source · skinsort.com ⟶
02

Product index

Related product references

03

Comparison edit

Read side by side

Continue reading

Related articles