Allies of Skin 35% Vitamin C+ Perfecting Serum Versus Sunday Riley C.E.O. 15% Vitamin C Brightening Serum
Updated on July 18, 2023
Overview
What they are
These products are both cruelty-free and reef safe . They have a total of 3 ingredients in common
Cool Features
They both contain Vitamin C
Suited For
They're both likely to be good for anti aging, brightening skin, reducing pores, dark spots and better texture
Free From
They both do not contain any harsh alcohols, common allergens, parabens, silicones or sulfates
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Ingredient Info
Allies of Skin 35% Vitamin C+ Perfecting Serum 10 ingredients
Sunday Riley C.E.O. 15% Vitamin C Brightening Serum 22 ingredients
About this product
About this product
At a glance
Click on any of the items below to learn more
Allies of Skin 35% Vitamin C+ Perfecting Serum 10 ingredients
Sunday Riley C.E.O. 15% Vitamin C Brightening Serum 22 ingredients
Key Ingredients
Benefits
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Ingredients Explained
These ingredients are found in both products.
Ingredients higher up in an ingredient list are typically present in a larger amount.
Tetrahexyldecyl Ascorbate (THD) is a stable and oil-soluble form of Vitamin C.
THD is special in that it has the ability to travel deeper into skin than traditional ascorbic acid while maintaining the same skin benefits (double win!).
Because it’s oil-soluble, THD dives deep into your skin’s fatty layers (think ceramides and cholesterol) to fight off the kind of free radicals that mess with your skin barrier. This makes it a great pair with water-based vitamin C (ascorbic acid) that mainly works on the surface.
Even at just 0.1%, THD is already showing great antioxidant activity. When used up to 2%, it helps keep your skin happy and calm, especially when it’s stressed from pollution or sun.
Want to fade dark spots or tackle hyperpigmentation? You’ll want 5% or more. Pairing it with brightening buddies like niacinamide or licorice root gives even better results. One study even used 30% THD with other brighteners and saw real results on stubborn discoloration, even in melasma-prone skin.
A note on THD: It’s has a slightly silky, oily texture and usually shows up colorless or pale yellow (though the exact shade can vary by supplier).
While you can sneak it into water-based formulas, it really shines when paired with silicones or oils, which help your skin soak it up better.
THD is pretty stable, but it’s still vulnerable to degradation like ascorbic acid. Too much light or heat (above 113°F / 45°C) can break it down over time. Go for dark and opaque packaging that keeps it safe and shady!
Read more about other types of Vitamin C:
Learn more about Tetrahexyldecyl AscorbateCaprylyl Glycol is a humectant and emollient, meaning it attracts and preserves moisture.
It is a common ingredient in many products, especially those designed to hydrate skin. The primary benefits are retaining moisture, skin softening, and promoting a healthy skin barrier.
Though Caprylyl Glycol is an alcohol derived from fatty acids, it is not the kind that can dry out skin.
This ingredient is also used as a preservative to extend the life of products. It has slight antimicrobial properties.
Learn more about Caprylyl GlycolPhenoxyethanol is a preservative that has germicide, antimicrobial, and aromatic properties. Studies show that phenoxyethanol can prevent microbial growth. By itself, it has a scent that is similar to that of a rose.
It's often used in formulations along with Caprylyl Glycol to preserve the shelf life of products.
Ingredient Ratings
Here's what our community thinks of the ingredients in these products.
When to use
Allies of Skin 35% Vitamin C+ Perfecting Serum 10 ingredients
Sunday Riley C.E.O. 15% Vitamin C Brightening Serum 22 ingredients

Reviews
Here's what our community thinks
Allies of Skin 35% Vitamin C+ Perfecting Serum 10 ingredients
Sunday Riley C.E.O. 15% Vitamin C Brightening Serum 22 ingredients
my favorite serum
I wear this every morning, combined with the Sunday Riley C.E.O. face oil. It has a great citrus scent. I feel that it has contributed to lightening my dark spots and giving me a brighter complexion.