Medik8 C-Tetra™ Advanced Gel-Serum
A vegan and cruelty-free serum that contains exfoliants, hyaluronic acid, vitamin c and vitamin e.
Overview
What it is
Serum with 31 ingredients that contains exfoliants, hyaluronic acid, Vitamin C and Vitamin E
Cool Features
It is vegan, cruelty-free, and reef safe
Suited For
It has ingredients that are good for anti aging, dry skin, brightening skin, sensitive skin, reducing pores, scar healing and better texture
Free From
It doesn't contain any harsh alcohols, parabens, silicones or sulfates
Fun facts
Medik8 is from United Kingdom. This product is used in 1 routines created by our community.
We independently verify ingredients and our claims are backed by peer-reviewed research. Does this product need an update? Let us know.
What's inside (and what isn't)
Ingredients List
Dive into the full list of ingredients.
Water
Skin ConditioningTetrahexyldecyl Ascorbate
AntioxidantIsododecane
EmollientPropanediol
SolventAcetyl Glucosamine
Skin ConditioningSqualane
EmollientTocopherol
AntioxidantAcetyl Zingerone
AntioxidantCamellia Sinensis Leaf
PerfumingHydroxyacetophenone
AntioxidantSodium Hyaluronate
HumectantCellulose
AbsorbentAvena Sativa Kernel Extract
AbrasiveGlycerin
HumectantHydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer
Emulsion StabilisingCitrus Grandis Peel Oil
MaskingSucrose Stearate
EmollientTetrasodium Glutamate Diacetate
Ethylhexylglycerin
Skin ConditioningAcrylates/C10-30 Alkyl Acrylate Crosspolymer
Emulsion StabilisingXanthan Gum
EmulsifyingSodium Benzoate
MaskingCellulose Gum
Emulsion Stabilising1,2-Hexanediol
Skin ConditioningPolysorbate 60
EmulsifyingSorbitan Isostearate
EmulsifyingCitric Acid
BufferingPhenoxyethanol
PreservativeCitral
PerfumingLinalool
PerfumingLimonene
PerfumingWater, Tetrahexyldecyl Ascorbate, Isododecane, Propanediol, Acetyl Glucosamine, Squalane, Tocopherol, Acetyl Zingerone, Camellia Sinensis Leaf, Hydroxyacetophenone, Sodium Hyaluronate, Cellulose, Avena Sativa Kernel Extract, Glycerin, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Citrus Grandis Peel Oil, Sucrose Stearate, Tetrasodium Glutamate Diacetate, Ethylhexylglycerin, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Xanthan Gum, Sodium Benzoate, Cellulose Gum, 1,2-Hexanediol, Polysorbate 60, Sorbitan Isostearate, Citric Acid, Phenoxyethanol, Citral, Linalool, Limonene
Key Ingredients
Benefits
Concerns
Ingredients Explained
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. Stay hydrated!
Learn more about WaterTetrahexyldecyl 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 AscorbateIsododecane is a fragrance, emollient, and solvent.
As an emollient, it helps your skin stay soft and hydrated. Emollients help trap moisture into your skin.
Isododecane's role as a solvent makes it a great texture enhancer. It spreads smoothly on skin and does not leave a sticky feeling behind. Isododecane also helps prevent color transfer in makeup products.
Isododecane is not absorbed into skin.
Learn more about IsododecanePropanediol 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.
Learn more about PropanediolAcetyl Glucosamine is an antioxidant and humectant. It is an amino acid sugar and is naturally found in our skin.
The cool thing about this ingredient? It helps the skin produce hyaluronic acid and boost hydration. It also has antioxidant benefits to protect skin cells.
When paired with niacinamide, Acetyl Glucosamine has been shown to be effective at reducing discoloration.
Learn more about Acetyl GlucosamineSqualane is an emollient that helps the skin hold onto moisture. It's an oily liquid that occurs naturally in certain types of fish and plant oils.
Because squalane boosts hydration in the skin, it also comes with plenty of benefits: it is an antioxidant and can help fight free radicals and skin damage. Squalane is also found to have a detoxifying effect when applied.
Squalane comes from squalene, which occurs naturally within the sebum of our skin. It is one of the oils our skin produces to keep itself hydrated. Squalane is the hydrogenated version of squalene and has a longer shelf life.
Research shows that squalane is non-irritating (even at 100% concentration).
In general, it's a fantastic ingredient. It does a great job at hydrating the skin, and it's suitable for those with sensitive skin.
The source of squalane may impact malassezia / fungal acne. This is because olive oil derived squalane can contain impurities such as fatty acids and plant waxes. Sugarcane derived squalane is recommended for anyone with malassezia concerns.
Is squalane vegan?
This depends on the source. Squalane can be derived from both plants and animals. Most squalane used in skincare comes from plants.
Please note: the source of squalane is only known if disclosed by the brand. We recommend reaching out to the brand if you have any questions about their squalane.
Read more about squalene with an "e".
Is squalane an oil?
Squalane is often called an oil, but it’s technically not; it’s a hydrocarbon, meaning it’s only made of carbon and hydrogen, unlike true oils which are triglycerides made of fatty acids and glycerol.
The term “oil-free” isn’t regulated, so companies can define it however they want. Some exclude all oils, while others just avoid mineral oil or comedogenic oils.
While some people avoid oils thinking they cause breakouts, the right kind of oil (or oil-like ingredient like squalane) can actually help balance and hydrate your skin. It’s worth testing out simple oils or squalane to see what works best for your skin.
Learn more about SqualaneTocopherol (also known as Vitamin E) is a common antioxidant used to help protect the skin from free-radicals and strengthen the skin barrier. It's also fat soluble - this means our skin is great at absorbing it.
Vitamin E also helps keep your natural skin lipids healthy. Your lipid skin barrier naturally consists of lipids, ceramides, and fatty acids. Vitamin E offers extra protection for your skin’s lipid barrier, keeping your skin healthy and nourished.
Another benefit is a bit of UV protection. Vitamin E helps reduce the damage caused by UVB rays. (It should not replace your sunscreen). Combining it with Vitamin C can decrease sunburned cells and hyperpigmentation after UV exposure.
You might have noticed Vitamin E + C often paired together. This is because it is great at stabilizing Vitamin C. Using the two together helps increase the effectiveness of both ingredients.
There are often claims that Vitamin E can reduce/prevent scarring, but these claims haven't been confirmed by scientific research.
Learn more about TocopherolAcetyl Zingerone is an antioxidant from ginger. It is able to fight many types of free-radical damage.
Acetyl Zingerone is stable in sun and is able to disrupt UV damaging processes on the skin.
Camellia Sinensis Leaf is the leaf of the tea plant. These leaves are used to make white, oolong, green, and black tea.
Tea leaves have many benefits. It contains polyphenols, a strong antioxidant. Antioxidants help fight off free-radical molecules that damage skin cells. The antioxidants in green tea neutralize free-radicals from the sun. This gives the skin some extra UV protection, but should not replace sunscreen.
Many components of tea have anti-inflammatory properties. Polyphenols and L-theanine help soothe the skin and reduce irritation. L-theanine is an amino acid that makes up most of the amino acids found in tea leaves. The caffeine in Camellia Sinensis Leaf Extract helps calm inflamed blood vessels.
Research has shown both drinking Camellia Sinensis Leaf Tea (green tea, white tea, oolong, black tea) and applying it to the skin can help boost skin elasticity and hydration. Studies also show using tea extract may reduce sebum, or oil, production.
Learn more about Camellia Sinensis LeafHydroxyacetophenone is antioxidant with skin conditioning and soothing properties. It also boosts the efficiency of preservatives.
This ingredient is not irritating or sensitizing.
Sodium Hyaluronate is hyaluronic acid's salt form. It is commonly derived from the sodium salt of hyaluronic acid.
Like hyaluronic acid, it is great at holding water and acts as a humectant. This makes it a great skin hydrating ingredient.
Sodium Hyaluronate is naturally occurring in our bodies and is mostly found in eye fluid and joints.
These are some other common types of Hyaluronic Acid:
Learn more about Sodium HyaluronateCellulose is the main component of plant cell walls. It is used as an emulsifier, absorbent, and texture enhancer.
This ingredient has many functions:
Fun fact: Cellulose is the most abundant form of organic polymer on Earth.
Learn more about CelluloseAvena Sativa Kernel Extract is is derived from colloidal oatmeal. Besides being a healthy breakfast, oats have many benefits in skincare too.
This ingredient helps sooth, hydrate, and protect the skin. The starches in colloidal oatmeal are able to bind water, keeping the skin hydrated.
The cellulose and fiber in colloidal oatmeal help reduce inflammation. This can also help the skin feel softer.
Colloidal Oatmeal is also an antioxidant. Antioxidants protect our skin from free-radical damage.
Oatmeal also contains beneficial compounds:
This ingredient is created by mixing grounded oatmeal and a liquid base.
Learn more about Avena Sativa Kernel ExtractGlycerin is already naturally found in your skin. It helps moisturize and protect your skin.
A study from 2016 found glycerin to be more effective as a humectant than AHAs and hyaluronic acid.
As a humectant, it helps the skin stay hydrated by pulling moisture to your skin. The low molecular weight of glycerin allows it to pull moisture into the deeper layers of your skin.
Hydrated skin improves your skin barrier; Your skin barrier helps protect against irritants and bacteria.
Glycerin has also been found to have antimicrobial and antiviral properties. Due to these properties, glycerin is often used in wound and burn treatments.
In cosmetics, glycerin is usually derived from plants such as soybean or palm. However, it can also be sourced from animals, such as tallow or animal fat.
This ingredient is organic, colorless, odorless, and non-toxic.
Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.
Learn more about GlycerinThis is a synthetic polymer. It helps improve the texture of products by adding thickness and gel-like feel.
It is also an emulsifer, meaning it prevents ingredients such as oil and water from separating. It also helps evenly disperse other ingredients.
Citrus Grandis Peel Oil is an essential oil that is derived from the peel of a Grapefruit. It is composed largely of limonene, which is a fragrance that can cause irritation for sensitive skin.
Sucrose Stearate is derived from stearic acid and sucrose (sugar). It is an emollient and emulsifier.
As an emulsifier, it prevents oils and water from separating in a product. This property also makes it a surfactant and therefore a cleansing agent.
Tetrasodium Glutamate Diacetate is a chelating agent. Chelating agents help prevent metal ions from binding to other ingredients. This helps prevent unwanted effects and reactions from a product. These metal ions may come from water and are found in miniscule amounts.
Tetrasodium Glutamate Diacetate can also help other preservatives be more effective.
Ethylhexylglycerin (we can't pronounce this either) is commonly used as a preservative and skin softener. It is derived from glyceryl.
You might see Ethylhexylglycerin often paired with other preservatives such as phenoxyethanol. Ethylhexylglycerin has been found to increase the effectiveness of these other preservatives.
Acrylates/C10-30 Alkyl Acrylate Crosspolymer is a synthetic polymer. It is used to thicken and improve the texture of products. Due to its properties, it can prevent water and oil ingredients from separating.
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.
Learn more about Xanthan GumSodium Benzoate is a preservative. It's used in both cosmetic and food products to inhibit the growth of mold and bacteria. It is typically produced synthetically.
Both the US FDA and EU Health Committee have approved the use of sodium benzoate. In the US, levels of 0.1% (of the total product) are allowed.
Sodium benzoate works as a preservative by inhibiting the growth of bacteria inside of cells. It prevents the cell from fermenting a type of sugar using an enzyme called phosphofructokinase.
It is the salt of benzoic acid. Foods containing sodium benzoate include soda, salad dressings, condiments, fruit juices, wines, and snack foods.
Studies for using ascorbic acid and sodium benzoate in cosmetics are lacking, especially in skincare routines with multiple steps.
We always recommend speaking with a professional, such as a dermatologist, if you have any concerns.
Learn more about Sodium BenzoateCellulose Gum is a water-soluble polymer that comes from cellulose. It is used to change the texture of a product and to help stabilize emulsions.
As an emulsifier, cellulose gum specifically thicken the texture of water-based products.
This ingredient is considered hypoallergenic and non-toxic. Cellulose Gum can be found in cosmetics, food, and other household goods such as paper products.
Learn more about Cellulose Gum1,2-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
Polysorbate 60 is used to help stabilize products. It is a surfactant and emulsifier. These properties help keep ingredients together in a product. Surfactants help reduce surface tension between ingredients with different states, such as liquids and solids. Emulsifiers help prevent oils and waters from separating.
Polysorbate 60 is sorbitol-based and created from the ethoxylation of sorbitan. Ethoxylation is a chemical reaction used to add ethylene oxide. Sorbitan is a the dehydrated version of sorbitol, a sugar found in fruits.
In this case, the 60 comes from reacting 60 units of ethylene oxide with sorbitan.
Polysorbates are commonly used in medicine and foods.
Learn more about Polysorbate 60Sorbitan Isostearate is an emulsifer and cleaning agent. It is created from isostearic acid and sorbitol.
As an emulsifier, Sorbitan Isostearate prevents oils and water from separating.
Due to its isostearic acid base, it may not be safe for Malassezia or fungal acne.
Learn more about Sorbitan IsostearateCitric Acid is an AHA derived from citrus fruits (think oranges, lemons, and limes!).
As an AHA, Citric Acid removes the top layer of skin cells from the newer layer of skin underneath. This helps skin to remove dark spots and even out skin tone.
If you spot Citric Acid near the end of an ingredient list, it's likely there as a pH adjuster rather than an active ingredient.
Read more about some other popular AHA's here:
Learn more about Citric AcidPhenoxyethanol 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.
Citral is a fragrance and used to add a lemon-like scent to products. It is both naturally found in plants and created synthetically. In plants, it is commonly occurring in lemon myrtle, lemongrass, lemon tea-tree, lemon verbena, and other citruses.
The EU mandates Citral be listed separately as a fragrance. It is a known allergen and may cause contact dermatitis. Citral can also used as a masking ingredient.
The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.
The term 'citral' is a collective term for two geometric isomers: geranial/Citral A and neral/Citral B.
Learn more about CitralLinalool is a fragrance and helps add scent to products. It's derived from common plants such as cinnamon, mint, citrus, and lavender.
Like Limonene, this ingredient oxidizes when exposed to air. Oxidized linalool can cause allergies and skin sensitivity.
This ingredient has a scent that is floral, spicy tropical, and citrus-like.
Learn more about LinaloolLimonene is a fragrance that adds scent and taste to a formulation.
It's found in the peel oil of citrus fruits and other plants such as lavender and eucalyptus. The scent of limonene is generally described as "sweet citrus".
Limonene acts as an antioxidant, meaning it helps neutralize free radicals.
When exposed to air, oxidized limonene may sensitize the skin. Because of this, limonene is often avoided by people with sensitive skin.
The term 'fragrance' is not regulated in many countries. In many cases, it is up to the brand to define this term. For instance, many brands choose to label themselves as "fragrance-free" because they are not using synthetic fragrances. However, their products may still contain ingredients such as essential oils that are considered a fragrance.
Learn more about LimoneneReviews
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Where it's from
Medik8 is a British brand
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The data we've presented on this page has been verified by a member of the SkinSort Team.
Read more about us· Updated May 8, 2025 • Added by amandalister