Skin science article
Paula's Choice 25% Vitamin C + Glutathione Clinical Serum Versus XYZ SKIN Star Bright Serum
Paula's Choice 25% Vitamin C + Glutathione Clinical Serum Versus XYZ SKIN Star Bright Serum This brightening serum is formulated around Tetrahexyldecyl Ascorbate and Ascorbyl Glucoside to brighten dull-looking skin and fade the look of dark spots. This brighte
Paula's Choice 25% Vitamin C + Glutathione Clinical Serum Versus XYZ SKIN Star Bright Serum
This brightening serum is formulated around Tetrahexyldecyl Ascorbate and Ascorbyl Glucoside to brighten dull-looking skin and fade the look of dark spots.
This brightening serum is formulated around Tetrahexyldecyl Ascorbate and Squalane to brighten dull-looking skin and hydrate skin.
What's inside
Key Ingredients
Benefits
Concerns
Ingredients Side-by-side
Water
Tetrahexyldecyl Ascorbate
Dimethicone
Glycerin
C9-12 Alkane
Ascorbyl Glucoside
Silica
Pyrus Malus Fruit Extract
Hydrogenated Lecithin
Polyglyceryl-6 Polyricinoleate
Acrylates/C10-30 Alkyl Acrylate Crosspolymer
Xanthan Gum
Oryza Sativa Bran Extract
Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer
Cetyl Alcohol
Caprylyl Glycol
Lysine Carboxymethyl Cysteinate
Coco-Caprylate/Caprate
Tocopherol
Glutathione
Sodium Citrate
Sodium Phytate
Hexylene Glycol
Ethylhexylglycerin
Helianthus Annuus Seed Extract
Urea
Mannitol
Caprylic/Capric Triglyceride
Sodium PCA
Rosmarinus Officinalis Leaf Extract
Polysorbate 60
Sorbitan Isostearate
Trehalose
Ascorbic Acid
Glucose
Vanilla Planifolia Fruit Extract
Polyquaternium-51
Ergothioneine
Triacetin
Sodium Hyaluronate
Phenoxyethanol
Water, Tetrahexyldecyl Ascorbate, Dimethicone, Glycerin, C9-12 Alkane, Ascorbyl Glucoside, Silica, Pyrus Malus Fruit Extract, Hydrogenated Lecithin, Polyglyceryl-6 Polyricinoleate, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Xanthan Gum, Oryza Sativa Bran Extract, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Cetyl Alcohol, Caprylyl Glycol, Lysine Carboxymethyl Cysteinate, Coco-Caprylate/Caprate, Tocopherol, Glutathione, Sodium Citrate, Sodium Phytate, Hexylene Glycol, Ethylhexylglycerin, Helianthus Annuus Seed Extract, Urea, Mannitol, Caprylic/Capric Triglyceride, Sodium PCA, Rosmarinus Officinalis Leaf Extract, Polysorbate 60, Sorbitan Isostearate, Trehalose, Ascorbic Acid, Glucose, Vanilla Planifolia Fruit Extract, Polyquaternium-51, Ergothioneine, Triacetin, Sodium Hyaluronate, Phenoxyethanol
Camellia Oleifera Leaf
Squalane
Rosa Rubiginosa Seed Oil
Hippophae Rhamnoides Oil
Cucumis Sativus Fruit Extract
Mentha Spicata Flower/Leaf/Stem Extract
Mentha Piperita Stem Extract
Geranium Maculatum Extract
Citrus Aurantium Amara Flower Extract
Camellia Oleifera Leaf, Squalane, Rosa Rubiginosa Seed Oil, Tetrahexyldecyl Ascorbate, Hippophae Rhamnoides Oil, Cucumis Sativus Fruit Extract, Mentha Spicata Flower/Leaf/Stem Extract, Mentha Piperita Stem Extract, Geranium Maculatum Extract, Citrus Aurantium Amara Flower Extract, Tocopherol
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Alternatives
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:
Tocopherol is a fat-soluble antioxidant known as Vitamin E.
You'll find this ingredient in the vast majority of skincare (for good reason). It works to neutralize free radicals, or unstable molecules generated by UV exposure, pollution, and other environmental stressors, before they can cause oxidative damage to your skin cells.
Topically applied tocopherol has been shown to protect against UV damage by ramping up the skin's own natural defense enzymes.
It also acts as a skin conditioning agent; some studies show that regular topical use can improve the skin's water-binding capacity over 2-4 weeks.
This ingredient is especially loved for being a team player. When combined with Vitamin C, the photoprotective effect of both ingredients roughly doubles and the combo also helps reduce UV-induced DNA damage.
This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.
In formulations, it also serves as a stabilizer that helps protect other oxidation-prone ingredients from degrading.
Concentrations usually range from 0.1-1% in most leave-on products.