HoliFrog Sunnyside C Glow Serum Versus Allies of Skin 20% Vitamin C Brighten + Firm Serum

HoliFrog Sunnyside C Glow Serum Versus Allies of Skin 20% Vitamin C Brighten + Firm Serum

This brightening serum is formulated around 3-O-Ethyl Ascorbic Acid and Tetrahexyldecyl Ascorbate to brighten dull-looking skin and fade the look of dark spots.

This brightening serum is formulated around 3-O-Ethyl Ascorbic Acid and Glutathione to brighten dull-looking skin.

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Aloe Barbadensis Leaf Juice

3-O-Ethyl Ascorbic Acid

Caprylic/Capric Triglyceride

Simmondsia Chinensis Seed Oil

Tetrahexyldecyl Ascorbate

Tranexamic Acid

Caprylyl Caprylate/Caprate

Glycerin

Niacinamide

Isomalt

Vitis Vinifera Seed Oil

Glyceryl Stearate

Cetearyl Glucoside

Glutathione

Tremella Fuciformis Sporocarp Extract

Inonotus Obliquus Extract

Sodium PCA

Tocopherol

Water

Citric Acid

Cetyl Alcohol

Phytol

Benzyl Alcohol

Hydroxyethylcellulose

Dehydroacetic Acid

Benzoic Acid

Sorbic Acid

Maltodextrin

Disodium Phosphate

Polysorbate 60

Sodium Phosphate

Aloe Barbadensis Leaf Juice, 3-O-Ethyl Ascorbic Acid, Caprylic/Capric Triglyceride, Simmondsia Chinensis Seed Oil, Tetrahexyldecyl Ascorbate, Tranexamic Acid, Caprylyl Caprylate/Caprate, Glycerin, Niacinamide, Isomalt, Vitis Vinifera Seed Oil, Glyceryl Stearate, Cetearyl Glucoside, Glutathione, Tremella Fuciformis Sporocarp Extract, Inonotus Obliquus Extract, Sodium PCA, Tocopherol, Water, Citric Acid, Cetyl Alcohol, Phytol, Benzyl Alcohol, Hydroxyethylcellulose, Dehydroacetic Acid, Benzoic Acid, Sorbic Acid, Maltodextrin, Disodium Phosphate, Polysorbate 60, Sodium Phosphate

Propanediol

Benzimidazole Diamond Amidoethyl Urea Carbamoyl Propyl Polymethylsilsesquioxane

Dimethyl Isosorbide

Helianthus Annuus Seed Wax

Polyglyceryl-10 Tristearate

Ethoxydiglycol

Dicaprylyl Ether

Caprylyl Glycol

Citrus Aurantium Dulcis Callus Culture Extract

Acetyl Cysteine

Dimethylmethoxy Chromanol

Ergothioneine

Gluconolactone

Leuconostoc/Radish Root Ferment Filtrate

Xanthan Gum

Silica

Sodium Benzoate

Calcium Gluconate

Phenoxyethanol

Propanediol, Glycerin, 3-O-Ethyl Ascorbic Acid, Benzimidazole Diamond Amidoethyl Urea Carbamoyl Propyl Polymethylsilsesquioxane, Dimethyl Isosorbide, Helianthus Annuus Seed Wax, Polyglyceryl-10 Tristearate, Ethoxydiglycol, Dicaprylyl Ether, Water, Caprylyl Glycol, Citrus Aurantium Dulcis Callus Culture Extract, Glutathione, Acetyl Cysteine, Dimethylmethoxy Chromanol, Ergothioneine, Tocopherol, Gluconolactone, Leuconostoc/Radish Root Ferment Filtrate, Xanthan Gum, Silica, Sodium Benzoate, Calcium Gluconate, Phenoxyethanol

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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.

3-O-Ethyl Ascorbic Acid is one of the most popular "stable" vitamin C derivatives in skincare.

Plain ascorbic acid is fantastic but notoriously fragile; it browns, oxidizes, and loses potency fast. So attaching an ethyl group to the third carbon of the molecule gives it some cool perks:

In a formula, it does the 3 classic vitamin C jobs: it acts as an antioxidant, helps brighten skin tone by inhibiting tyrosinase, and supports collagen.

The evidence is reasonably solid for a cosmetic ingredient; Liao and colleagues (2018) showed it's significantly more stable than ascorbic acid while still being effective.

A 2021 study by Zerbinati and colleagues tested a serum with 30% 3-O-ethyl-l-ascorbic acid and 1% lactic acid significantly increased collagen production, reduced UVB-induced DNA damage, and decreased melanin on a reconstructed pigmented skin model.

Typical real world usage sits around 0.5-5% (and 1-2% is common for daily serums).

Amounts up to 30% have been shown to be non-irritating on human skin samples, but two isolated cases reported allergic contact dermatitis so a patch test is sensible if you have reactive skin.

Glutathione is a tiny protein-like molecule (a "tripeptide" build from 3 amino acids: glycine, cysteine, and glutamic acid) that your body already makes on its own.

Inside your body, it acts as one of the skin's main antioxidants that help fight against free radicals.

In skincare, it's best known as a brightening ingredient that slows down tyrosinase, the key enzyme that makes skin pigment. It also nudges the skin toward making a lighter type of pigment instead of a darker one.

This is why you'll see it in products aimed at dark spots and uneven tone.

A small number of real human trials have found a topical glutathione lotion:

The honest caveat is that the current evidence is still thin (few studies, small groups, short timelines). Glutathione also doesn't absorb into skin very easily so results tend to be modest and fade if you stop using it.

One thing worth clearing up:

The scary side effects you may have heard about come from glutathione injected intravenously, which has real safety concerns. Applying it topically is a completely different thing and has a clean track record.

Most human studies used it around 2% (as Glutathione or Glutathione Disulfide) and a 2% oxidized glutathione lotion and a 2% S-acyl glutathione cream are the concentrations with actual clinical data behind them.

There's no established "ideal" percentage yet but 1-2% is the evidence-backed range.

Allergy-wise, there is very low risk for this ingredient; it was well-tolerated across the topical trials. Only one participant had mild temporary redness that cleared up on its own and another study reported no adverse reactions at all.

One trial had ~10% of users drop out for irritation was using a combination cream that also had 10% azelaic acid so the irritation likely wasn't from the glutathione. There's no notable contact-allergy signal for topical glutathione in the literature but patch-testing before first use is still sensible for those with sensitive skin.

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.

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.

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!

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