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Medik8 C-Tetra® Cream

C-Tetra® Cream

The perfect introduction to anti-ageing skincare, C-Tetra Cream shields skin from free radical damage and restores radiance. Hyaluronic acid and glycerin leave skin supple and hydrated, while also supporting skin’s natural barrier. This deeply hydrating yet lightweight cream includes natural citrus extracts which give it an uplifting scent, making it the perfect way to start your morning.
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Ingredients overview

*Although we try our best to ensure this list of ingredients is accurate there may be product upgrades from time to time, or slight variants between different regions based on local laws, meaning the only definitive ingredient list is that which is printed on the product packaging.

Medik8 C-Tetra® Cream
Ingredients explained

Also-called: Water | What-it-does: solvent

Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product. 

It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water. 

What-it-does: emollient

We don't have description for this ingredient yet.

What-it-does: emollient

A super common emollient that makes your skin feel nice and smooth. It comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. It’s a nice ingredient that just feels good on the skin, is super well tolerated by every skin type and easy to formulate with. No wonder it’s popular. 

What-it-does: solvent

It's a type of glycol that - according to the manufacturer - is an extremely good replacement for other glycols like propylene or butylene glycol. Its main job is to be a solvent, but it has also very good antimicrobial properties and acts as a true preservative booster. Also helps with skin hydration without stickiness or tacky feel.

Also-called: Form of Vitamin C, THDA | What-it-does: antioxidant, skin brightening

Tetrahexyldecyl Ascorbate is a stable, oil-soluble form of skincare big shot Vitamin C. If you do not know, why Vitamin C is such a big deal in skincare, click here and read all about it. We are massive vitamin C fans and have written about it in excruciating detail.

So now, you know that Vitamin C is great and all, but it's really unstable and gives cosmetics companies many headaches. To solve this problem they came up with vitamin C derivatives, and one of them is Tetrahexyldecyl Ascorbate (let's call it THDA in short).

Also-called: Part of Olivem 1000 | What-it-does: emulsifying

An ester that comes from Cetearyl alcohol and the fatty acids of olive oil. It often comes to the formula coupled with Sorbitan Olivate as the two together form the well-known, natural emulsifier trade named Olivem 1000. 

Other than helping oil and water to blend, the main thing of Olivem 1000 is generating liquid crystal structures that are similar to the lipid structures of the stratum corneum (the outermost layer of the skin). Thanks to this, Olivem 1000 doubles as an active ingredient with significant moisturizing, barrier-repairing and soothing properties.

What-it-does: absorbent/mattifier

We don't have description for this ingredient yet.

Also-called: Vitamin E Acetate | What-it-does: antioxidant | Irritancy: 0 | Comedogenicity: 0

It’s the most commonly used version of pure vitamin E in cosmetics. You can read all about the pure form here. This one is the so-called esterified version. 

According to famous dermatologist, Leslie Baumann while tocopheryl acetate is more stable and has a longer shelf life, it’s also more poorly absorbed by the skin and may not have the same awesome photoprotective effects as pure Vit E. 

What-it-does: emollient

It's a clear, slightly yellowish oil (comes from coconut or palm kernel oil) that is used as a traditional, medium spreading emollient

What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0

It’s the - sodium form - cousin of the famous NMFhyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here.  The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.

As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit  "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution". 

Glycerin - superstar
Also-called: Glycerol | What-it-does: skin-identical ingredient, moisturizer/humectant | Irritancy: 0 | Comedogenicity: 0
  • A natural moisturizer that’s also in our skin
  • A super common, safe, effective and cheap molecule used for more than 50 years
  • Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
  • Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
  • High-glycerin moisturizers are awesome for treating severely dry skin
Read all the geeky details about Glycerin here >>

Also-called: Part of Olivem 1000 | What-it-does: emulsifying

An ester coming from sorbitol and the fatty acids of olive oil. It is part of the popular emulsifier trade named Olivem 1000 that is well-known for generating biomimetic liquid crystal structures. We have more info on Olivem 1000 at Cetearyl Olivate >>

It’s a handy multi-tasking ingredient that gives the skin a nice, soft feel. At the same time, it also boosts the effectiveness of other preservatives, such as the nowadays super commonly used phenoxyethanol

The blend of these two (caprylyl glycol + phenoxyethanol) is called Optiphen, which not only helps to keep your cosmetics free from nasty things for a long time but also gives a good feel to the finished product. It's a popular duo.

Also-called: Grapefruit Peel Oil | What-it-does: perfuming

The essential oil coming from the rind of the grapefruit. In general, the main component of citrus peel oils is limonene (86-95% for grapefruit peel), a super common fragrant ingredient that makes everything smell nice (but counts as a frequent skin sensitizer).

Other than that, citrus peel also contains the problematic compound called furanocoumarin that makes them mildly phototoxic. In general, the more sour-bitter the fruit, the more problematic it is regarding phototoxicity: orange and clementine peel contain less of it while lemon, grapefruit, and bergamot contain some more. Be careful with it if it is in a product for daytime use.  

What-it-does: chelating

Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.

It is typically used in tiny amounts, around 0.1% or less.

Also-called: Bergamot Fruit Oil | What-it-does: perfuming

The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%). 

A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic compounds called furanocoumarins, but more and more commonly furanocoumarin-free versions are used in cosmetic products. Still, if you have sensitive skin and prefer fragrance-free products, bergamot oil is not for you.

Linalool - icky
What-it-does: perfuming, deodorant

Linalool is a super common fragrance ingredient. It’s kind of everywhere - both in plants and in cosmetic products. It’s part of 200 natural oils including lavender, ylang-ylang, bergamot, jasmine, geranium and it can be found in 90-95% of prestige perfumes on the market. 

The problem with linalool is, that just like limonene it oxidises on air exposure and becomes allergenic. That’s why a product containing linalool that has been opened for several months is more likely to be allergenic than a fresh one.

A superabsorbent polymer (big molecule from repeated subunits) that has crazy water binding abilities. Sometimes its referred to as "waterlock" and can absorb 100 to 1000 times its mass in water. 

As for its use in cosmetic products, it is a handy multi-tasker that thickens up water-based formulas and also has some emulsifying and emulsion stabilizing properties. 

What-it-does: perfuming

Citronellol is a very common fragrance ingredient with a nice rose-like odor. In the UK, it’s actually the third most often listed perfume on the ingredient lists. 

It can be naturally found in geranium oil (about 30%) or rose oil (about 25%). 

Also-called: lye | What-it-does: buffering

The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right. 

For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.  

What-it-does: perfuming, solvent

A naturally occurring floral component with a delicate scent that can mask the odor of other raw materials but is not noticeable in the final product. It also has remarkable antimicrobial and preservative boosting abilities and can help to create "preservative-free" formulas.

Also-called: Lemon Peel Oil | What-it-does: perfuming

The essential oil coming from the rind of the lemon that we make (or should make) lemonade from. In general, there are two problems with citrus peel oils: first, they are essentially the fragrant component, limonene in disguise (they are about 85-98% limonene).

Second, they contain the problematic compounds called furanocoumarins that make them mildly phototoxic. Lemon peel contains a medium amount of them, more than sweet orange but less than bergamot. Be careful with it especially if it is in a product for daytime use.  

Also-called: Rose Geranium Flower Essential Oil | What-it-does: perfuming

The fragrant essential oil coming from the flowers of Rose Geranium. Like most essential oils, it contains antioxidant and antimicrobial components, but the main ones are fragrant constituents (like citronellol and geraniol). Be careful with it, if your skin is sensitive. 

Limonene - icky
What-it-does: perfuming, solvent, deodorant

A super common and cheap fragrance ingredient. It's in many plants, e.g. rosemary, eucalyptus, lavender, lemongrass, peppermint and it's the main component (about 50-90%) of the peel oil of citrus fruits.

It does smell nice but the problem is that it oxidizes on air exposure and the resulting stuff is not good for the skin. Oxidized limonene can cause allergic contact dermatitis and counts as a frequent skin sensitizer

Geraniol - icky
What-it-does: perfuming

Geraniol is a common fragrance ingredient. It smells like rose and can be found in rose oil or in small quantities in geranium, lemon and many other essential oils. 

Just like other similar fragrance ingredients (like linalool and limonene) geraniol also oxidises on air exposure and becomes allergenic. Best to avoid if you have sensitive skin.

Citral - icky
What-it-does: perfuming

It’s a common fragrance ingredient that smells like lemon and has a bittersweet taste.  It can be found in many plant oils, e.g. lemon, orange, lime or lemongrass. 

It’s one of the “EU 26 fragrances” that has to be labelled separately (and cannot be simply included in the term “fragrance/perfume” on the label) because of allergen potential. Best to avoid if your skin is sensitive.

You may also want to take a look at...

what‑it‑does solvent
Normal (well kind of - it's purified and deionized) water. Usually the main solvent in cosmetic products. [more]
what‑it‑does emollient
what‑it‑does emollient
A very common emollient that makes your skin feel nice and smooth. Comes from coconut oil and glycerin, it’s light-textured, clear, odorless and non-greasy. [more]
what‑it‑does solvent
A type of glycol. Its main job is to be a solvent, but it has also very good antimicrobial properties and acts as a true preservative booster. [more]
what‑it‑does antioxidant | skin brightening
A stable, oil-soluble form of Vitamin C, that might have (in-vitro results) all the magic abilities of pure vitamin C (antioxidant, collagen booster, skin brightener). [more]
what‑it‑does emulsifying
Part of Olivem 1000, a natural emulsifier duo that is known for forming biomimetic liquid crystal structures. It doubles as an active ingredient with barrier repairing and soothing properties. [more]
what‑it‑does antioxidant
irritancy, com. 0, 0
A form of vitamin E that works as an antioxidant. Compared to the pure form it's more stable, has longer shelf life, but it's also more poorly absorbed by the skin. [more]
what‑it‑does emollient
A clear, slightly yellowish oil (comes from coconut or palm kernel oil) that is used as a traditional, medium spreading emollient.
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
It's the salt form of famous humectant and natural moisturizing factor, hyaluronic acid. It can bind huge amounts of water and it's pretty much the current IT-moisturizer. [more]
what‑it‑does skin-identical ingredient | moisturizer/humectant
irritancy, com. 0, 0
A real oldie but a goodie. Great natural moisturizer and skin-identical ingredient that plays an important role in skin hydration and general skin health. [more]
what‑it‑does emulsifying
An ester coming from sorbitol and the fatty acids of olive oil. It often comes to the formula coupled with Cetearyl Olivate and the two together help water and oil to blend (emulsifier). It's a natural and Ecocert approved duo.
what‑it‑does moisturizer/humectant | emollient
A handy multi-tasking ingredient that gives the skin a nice, soft feel and also boosts the effectiveness of other preservatives. [more]
what‑it‑does perfuming
The essential oil coming from the rind of the grapefruit. Its main component (86-95%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does chelating
Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes. [more]
what‑it‑does perfuming
The essential oil coming from the fruit (probably the rind) of the bergamot orange.  It's a common top note in perfumes and contains (among others) fragrant compounds limonene (37%), linalyl acetate (30%) and linalool (8.8%).  A well-known issue with bergamot oil (apart from the fragrance allergens) is that it contains phototoxic  [more]
what‑it‑does perfuming
A super common fragrance ingredient that can be found among others in lavender, ylang-ylang, bergamot or jasmine. The downside of it is that it oxidises on air exposure and might become allergenic. [more]
what‑it‑does viscosity controlling
A big polymer (a molecule from repeated subunits) with crazy water binding abilities. Used as a thickening and emulsion stabilizing agent. [more]
what‑it‑does perfuming
A common fragrance ingredient with a nice rose-like smell. [more]
what‑it‑does buffering
Lye - A solid white stuff that’s very alkaline and used in small amount to adjust the pH of the product.  [more]
what‑it‑does perfuming | solvent
A naturally occurring floral component with a delicate scent that can mask the odor of other raw materials. It also has remarkable antimicrobial and preservative boosting abilities.
what‑it‑does perfuming
The essential oil coming from the rind of the lemon. Its main component (83-97%) is limonene, the super common fragrant ingredient. [more]
what‑it‑does perfuming
The essential oil coming from the flowers of Rose Geranium. Like most essential oils, it contains antioxidant and antimicrobial components, but the main ones are fragrant constituents. [more]
what‑it‑does perfuming | solvent
A super common fragrance ingredient found naturally in many plants including citrus peel oils, rosemary or lavender. It autoxidizes on air exposure and counts as a common skin sensitizer. [more]
what‑it‑does perfuming
A common fragrance ingredient that smells like rose and can be found in rose oil. [more]
what‑it‑does perfuming
A common fragrance ingredient that smells like lemon. [more]