Peptide Skincare & BeautySkin science and ingredient guides

Skin science article

Obagi Professional-C Serum 20% Versus Obagi Retinol 1.0

Obagi Professional-C Serum 20% Versus Obagi Retinol 1.0 This brightening serum is formulated around Ascorbic Acid and Ascorbyl Glucoside to brighten dull-looking skin and soften the look of wrinkles. This anti-aging treatment is formulated around Retinol to so

Obagi Professional-C Serum 20% Versus Obagi Retinol 1.0

This brightening serum is formulated around Ascorbic Acid and Ascorbyl Glucoside to brighten dull-looking skin and soften the look of wrinkles.

This anti-aging treatment is formulated around Retinol to soften the look of wrinkles and refine skin texture.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Propylene Glycol

Water

Ascorbic Acid

Alcohol

Ascorbyl Glucoside

Ethoxydiglycol

Phenoxyethanol

Sorbitol

Sodium Hyaluronate

Zinc Chloride

Calcium Hydroxide

Parfum

Propylene Glycol, Water, Ascorbic Acid, Alcohol, Ascorbyl Glucoside, Ethoxydiglycol, Phenoxyethanol, Sorbitol, Sodium Hyaluronate, Zinc Chloride, Calcium Hydroxide, Parfum

Caprylic/Capric Triglyceride

Glyceryl Stearate

Cyclopentasiloxane

Butylene Glycol

Stearic Acid

Butyrospermum Parkii Butter

Polysorbate 60

Stearyl Alcohol

Glycerin

Allyl Methacrylates Crosspolymer

Retinol

Polysorbate 20

Dimethicone

Simmondsia Chinensis Seed Oil

Chamomilla Recutita Flower Extract

Hypericum Perforatum Flower Extract

Malva Sylvestris Flower Extract

Salvia Officinalis Leaf Extract

Sambucus Nigra Flower Extract

Cyclohexasiloxane

Tocopheryl Acetate

Ubiquinone

BHT

Bisabolol

Dimethicone/Vinyl Dimethicone Crosspolymer

Dipotassium Glycyrrhizate

Disodium EDTA

Triethanolamine

Carbomer

Glyceryl Acrylate/Acrylic Acid Copolymer

Caprylyl Glycol

Ethylhexylglycerin

Hexylene Glycol

Water, Caprylic/Capric Triglyceride, Glyceryl Stearate, Cyclopentasiloxane, Butylene Glycol, Stearic Acid, Butyrospermum Parkii Butter, Polysorbate 60, Stearyl Alcohol, Glycerin, Allyl Methacrylates Crosspolymer, Retinol, Polysorbate 20, Dimethicone, Simmondsia Chinensis Seed Oil, Chamomilla Recutita Flower Extract, Hypericum Perforatum Flower Extract, Malva Sylvestris Flower Extract, Salvia Officinalis Leaf Extract, Sambucus Nigra Flower Extract, Cyclohexasiloxane, Sorbitol, Tocopheryl Acetate, Ascorbic Acid, Ubiquinone, Sodium Hyaluronate, Propylene Glycol, BHT, Bisabolol, Dimethicone/Vinyl Dimethicone Crosspolymer, Dipotassium Glycyrrhizate, Disodium EDTA, Triethanolamine, Carbomer, Glyceryl Acrylate/Acrylic Acid Copolymer, Caprylyl Glycol, Ethylhexylglycerin, Hexylene Glycol, Phenoxyethanol

Alternatives

Ingredients Explained

These ingredients are found in both products.

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

Ascorbic Acid is is pure Vitamin C and is the biologically active form used directly by skin.

Not only is vitamin C great for your overall health and immune system, but it also has plenty of benefits for your skin. It is best supported by academic literature for:

Topical vitamin C has been shown to help neutralize oxidative stress from UV and pollution, helping to improve photoaging and hyperpigmentation when used consistently.

One clinical study found that using 5% topical vitamin C for six months improved signs of photodamaged skin, both on the surface and in the deeper structural layers of the skin.

While vitamin C doesn’t replace sunscreen, studies show it can boost photoprotection when combined with Vitamin E and ferulic acid. These two ingredients help improve stability and protective effects.

The big downside of this ingredient is formulation difficulty. Vitamin C is prone to oxidation and doesn't penetrate the skin unless formulated correctly. Research found that vitamin C absorbs into the skin best at a low pH (< 3.5) with about 20% being the upper limit for effective absorption.

Skin levels can saturate after repeated application; this means your skin won’t keep absorbing more once it’s full of vitamin C. This is why more isn’t always better with vitamin C and why very high concentrations don’t necessarily give extra benefits.

Ascorbic acid generally works well with many skincare ingredients but can be irritating when combined with other active ingredients. Strong oxidizing acne treatments like benzoyl peroxide can reduce the effectiveness of vitamin C if they are used at the same time; they are often recommended for use at different times of day.

Read more about other types of Vitamin C:

Foods rich with vitamin C include oranges, strawberries, broccoli, bell peppers, and more. When consuming Vitamin C, your skin receives a portion of the nutrients.

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.

Propylene Glycol is a synthetic, colorless, odorless liquid that has been a staple in cosmetics for decades. It is a skin conditioning agent, humectant, and solvent.

As a humectant, it draw water to the skin to reduce flaking and restore suppleness. It's also a solvent that helps dissolve other actives and keeps formulas stable across temperature changes.

The CIR Expert Panel has confirmed this ingredient to be nontoxic and clinical studies show no sensitization at cosmetic use concentrations.

True allergic reactions are quite rare: a 15-year retrospective study of 6,751 patients found only 0.31% had a positive reaction (and less than half were considered clinically relevant).

It seemed that when sensitization does occur, it's most commonly linked to topical medication (like corticosteroids) and not cosmetics. Allergic contact dermatitis also appears largely limited to individuals with underlying skin conditions.

Overall, propylene glycol is a well-studied ingredient that most people can tolerate without issue.

Sodium Hyaluronate is the salt form of hyaluronic acid. It is a long sugar chain that is naturally found in your skin, joints, and connective tissue that maintains hydration and elasticity.

In skincare, it works as a humectant. It pulls water from the environment and deeper layers of skin and binds it to the surface.

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.

Sorbitol is a sugar alcohol. It is a hydrating and moisturizing agent created from the reduction process of glucose.

Most sorbitol is usually made from potato starch. It is also found in fruits such as apples and pears.

As a humectant, Sorbitol helps draw water to the skin. This helps keep the skin hydrated. Sorbitol also helps create a thicker texture in products. You might find sorbitol in your toothpaste and other gels.

It is a non-irritating ingredient that is great for those with dry skin.

Sorbitol is a prebiotic. It helps promote the growth of healthy bacteria on your skin. The bacteria on your skin form a microbiome. This microbiome helps protect your skin from infection and harmful bacteria.

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. 03Ascorbic Acid is is pure Vitamin C and is the biologically active form used directly by skin.
  4. 04Not only is vitamin C great for your overall health and immune system, but it also has plenty of benefits for your skin. It is best supported by academic literature for:
  5. 05Topical vitamin C has been shown to help neutralize oxidative stress from UV and pollution, helping to improve photoaging and hyperpigmentation when used consistently.
  6. 06One clinical study found that using 5% topical vitamin C for six months improved signs of photodamaged skin, both on the surface and in the deeper structural layers of the skin.
  7. 07While vitamin C doesn’t replace sunscreen, studies show it can boost photoprotection when combined with Vitamin E and ferulic acid. These two ingredients help improve stability and protective effects.
  8. 08The big downside of this ingredient is formulation difficulty. Vitamin C is prone to oxidation and doesn't penetrate the skin unless formulated correctly. Research found that vitamin C absorbs into the skin best at a low pH (< 3.5) with about 20% be…
  9. 09Skin levels can saturate after repeated application; this means your skin won’t keep absorbing more once it’s full of vitamin C. This is why more isn’t always better with vitamin C and why very high concentrations don’t necessarily give extra benefits.
  10. 10Ascorbic acid generally works well with many skincare ingredients but can be irritating when combined with other active ingredients. Strong oxidizing acne treatments like benzoyl peroxide can reduce the effectiveness of vitamin C if they are used at…
  11. 11Read more about other types of Vitamin C:
  12. 12Foods rich with vitamin C include oranges, strawberries, broccoli, bell peppers, and more. When consuming Vitamin C, your skin receives a portion of the nutrients.
  13. 13Phenoxyethanol is one of the most widely used preservatives in skincare (and for good reason!).
  14. 14It 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.
  15. 15On 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.
  16. 16Another perk of this ingredient is that it stays functional across a wide pH range (3-10).
  17. 17You'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.
  18. 18Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.
  19. 19Safety-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.
  20. 20Adverse 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.
Source · skinsort.com
02

Product index

Related product references

Product

Obagi Professional-C Serum 20%

Obagi Professional-C Serum 20% Ingredients in Obagi Professional-C Serum 20% explained: benefits, concerns, and detailed analysis of 12 ingredients including Propylene Glycol, Water, and As…

Source: skinsort.comView reference →
03

Comparison edit

Read side by side