One Thing Niacinamide Glutathione Serum Versus innisfree Vitamin C Green Tea Enzyme Brightening Serum

One Thing Niacinamide Glutathione Serum Versus innisfree Vitamin C Green Tea Enzyme Brightening Serum

This brightening serum is formulated around Niacinamide and Glutathione to brighten dull-looking skin and fade the look of dark spots.

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

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Side-by-side

Water

Niacinamide

Butylene Glycol

Glycerin

Propanediol

1,2-Hexanediol

Hydroxyacetophenone

Glycereth-25 PCA Isostearate

Coptis Japonica Root Extract

Citric Acid

Ethylhexylglycerin

Citrus Unshiu Peel Extract

Xanthan Gum

Zea Mays Silk Extract

Disodium EDTA

Glutathione

Hyaluronic Acid

Hydrolyzed Hyaluronic Acid

Sodium Hyaluronate

Fructan

Melaleuca Alternifolia Leaf Extract

Glucose

3-O-Ethyl Ascorbic Acid

Ascorbic Acid

Sodium Ascorbate

Tocopheryl Acetate

Linoleic Acid

Tocopherol

Helianthus Annuus Seed Oil

Oleic Acid

Palmitic Acid

Stearic Acid

Linolenic Acid

Water, Niacinamide, Butylene Glycol, Glycerin, Propanediol, 1,2-Hexanediol, Hydroxyacetophenone, Glycereth-25 PCA Isostearate, Coptis Japonica Root Extract, Citric Acid, Ethylhexylglycerin, Citrus Unshiu Peel Extract, Xanthan Gum, Zea Mays Silk Extract, Disodium EDTA, Glutathione, Hyaluronic Acid, Hydrolyzed Hyaluronic Acid, Sodium Hyaluronate, Fructan, Melaleuca Alternifolia Leaf Extract, Glucose, 3-O-Ethyl Ascorbic Acid, Ascorbic Acid, Sodium Ascorbate, Tocopheryl Acetate, Linoleic Acid, Tocopherol, Helianthus Annuus Seed Oil, Oleic Acid, Palmitic Acid, Stearic Acid, Linolenic Acid

Betaine

Erythritol

Lactobacillus Ferment Lysate

Squalane

Acrylates/C10-30 Alkyl Acrylate Crosspolymer

Dextrin

Tromethamine

Gluconolactone

Panthenol

Carnosine

Allantoin

Caprylic/Capric Triglyceride

Daucus Carota Sativa Root Extract

Pentylene Glycol

Sodium Metaphosphate

Silica Dimethyl Silylate

Cyclodextrin

Madecassoside

Ascorbyl Tetraisopalmitate

Salix Alba Bark Extract

Dipotassium Glycyrrhizate

Protease

Tranexamic Acid

Achillea Millefolium Extract

Beta-Carotene

Ferulic Acid

Sodium Hyaluronate Crosspolymer

Sodium Acetylated Hyaluronate

Water, Propanediol, Glycerin, 1,2-Hexanediol, 3-O-Ethyl Ascorbic Acid, Betaine, Erythritol, Butylene Glycol, Lactobacillus Ferment Lysate, Squalane, Helianthus Annuus Seed Oil, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Dextrin, Xanthan Gum, Tromethamine, Gluconolactone, Citrus Unshiu Peel Extract, Panthenol, Carnosine, Niacinamide, Allantoin, Hyaluronic Acid, Caprylic/Capric Triglyceride, Daucus Carota Sativa Root Extract, Pentylene Glycol, Sodium Metaphosphate, Silica Dimethyl Silylate, Tocopherol, Ethylhexylglycerin, Cyclodextrin, Madecassoside, Ascorbyl Tetraisopalmitate, Salix Alba Bark Extract, Dipotassium Glycyrrhizate, Protease, Tranexamic Acid, Glutathione, Achillea Millefolium Extract, Sodium Hyaluronate, Beta-Carotene, Ferulic Acid, Hydrolyzed Hyaluronic Acid, Sodium Hyaluronate Crosspolymer, Sodium Acetylated Hyaluronate

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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.

1,2-Hexanediol is a synthetic liquid and another multi-functional powerhouse.

It is a:

Humectant, drawing moisture into the skin

Emollient, helping to soften skin

Solvent, dispersing and stabilizing formulas

Preservative booster, enhancing the antimicrobial activity of other preservatives

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.

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Though 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.

This ingredient comes from the peel of the satsuma mandarin fruit native to Japan.

Unlike other citrus ingredients, this one is not known to cause photosensitivity. This is because the citrus ingredients that cause sensitivity are high in furanocoumarins. When exposed to UV, furocoumarins bind to and destabilize your DNA, speeding up the rate of sunburn.

Citrus Unshiu Peel Extract is unique in that the peel contains very low levels of furanocoumarins and tested products with this ingredient confirmed no detectable furanocoumarins.

The peel is rich in antioxidants and lab studies show it can help brighten skin by inhibiting tyrosinase, the enzyme responsible for melanin production.

One study on the fermented version of this ingredient found it could help reduce UVA-induced collagen breakdown. Though it is worth noting that while results are promising, robust human clinical trials are still needed.

This ingredient naturally contains limonene and other aromatic compounds that make it a perfuming ingredient.

The official COSING database only lists this ingredient as having "Perfuming" properties at this time. The brightening, antioxidant, and skin conditioning benefits that brands market come from the research literature and from how formulators choose to use the ingredient.

Ethylhexylglycerin is created from glycerin. It is a multitasker ingredient that:

The CIR Expert Panel found minimal skin absorption or sensitization of any kind in a safety assessment. Though this ingredient is considered well-tolerated, a small number of cases of allergic dermatitis have been published since 2002. Just be sure to patch test if you are unsure.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.

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.

Helianthus Annuus Seed Oil is a plant oil derived from the seeds of a sunflower.

It is rich in fatty acids, primarily linoleic acid and oleic acid. This gives it emollient and skin conditioning properties.

The reason this ingredient is so effective is because it forms a thin film on the skin that reduces transepidermal water loss (TEWL) while supplying linoleic acid to the stratum corneum to improve barrier strength.

The high linoleic acid content is particularly noteworthy for acne-prone skin.

Research suggests that acne-prone skin tends to be deficient in linoleic acid in sebum. Topical application may help replenish this to support a healthier follicular environment and less comedone-promoting sebum.

One randomized study found sunflower seed oil preserved skin barrier integrity in adult volunteers with and without atopic dermatitis (outperforming olive oil).

This ingredient is well-studied, gentle, and an effective emollient suitable for most skin types.

On fungal acne: This ingredient may not be Fungal acne (Malassezia folliculitis) safe. This is because it contains fatty acids with carbon chain lengths in the C11-C24 range.

Hyaluronic acid (HA) is a glycosaminoglycan (basically a long sugar chain) that your skin already makes on its own. In your skin, HA lives in the extracellular matrix and acts as the body's moisture reservoir.

Topically, HA is a humectant that binds water and helps skin look more plump, smooth, and hydrated.

The only catch is that HA isn't a single thing; it actually comes in a wide range of molecular weights (~50 - 2,000+ kDA) and size matters.

Some clinical evidence links low molecular weight versions to improved wrinkle depth, elasticity, anti-inflammatory effects, and barrier repair.

This is why the best HA serums blend the two sizes together so you get the best of both worlds.

The majority of cosmetic HA is produced by bacterial fermentation, typically using Streptococcus or Bacillus strains. Typical use levels in skincare sit around 0.1-2%.

A clinical study using a 0.2% low-molecular weight HA gel showed improvement in facial seborrheic dermatitis with excellent tolerance.

These are some other common types of Hyaluronic Acid:

Hydrolyzed Hyaluronic Acid is hyaluronic acid (HA) that is broken down into lower molecular weight fragments.

It's a humectant that pulls and holds water in the skin to help with hydration, plumpness, and reduce transepidermal water loss.

Because hydrolyzed hyaluronic acid is smaller in size, it can slip past your outermost layer of skin more easily than full-sized HA.

Most formulations will combine all sizes to get the best of both worlds.

Typical usage levels range from 0.01-1%. Any percentage higher than 2% might become goopy and tacky.

Niacinamide is a multitasking form of vitamin B3 that strengthens the skin barrier, reduces pores and dark spots, regulates oil, and improves signs of aging.

And the best part? It's gentle and well-tolerated by most skin types, including sensitive and reactive skin.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

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.

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:

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.

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!

Xanthan gum is used as a stabilizer and thickener within cosmetic products. It helps give products a sticky, thick feeling - preventing them from being too runny.

On the technical side of things, xanthan gum is a polysaccharide - a combination consisting of multiple sugar molecules bonded together.

Xanthan gum is a pretty common and great ingredient. It is a natural, non-toxic, non-irritating ingredient that is also commonly used in food products.

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