C12-13 Pareth-3 See Polyethylene glycol, a mixture of synthetic fatty acids and ethylene glycol.

C12-15 alkyl benzoate Blend of synthetic compounds, used in moisturisers, with a preserving effect. There are no known adverse effects for this ingredient.

Caffeine Obtained as a by-product of decaf coffee, it’s used as a stimulant and flavouring in lipsticks (giving that lip-plumping ‘tingle’, in some cases), and helps ingredients to penetrate the skin, while having a locally stimulating effect. It’s most widely used in cellulite treatments because of that circulation-boosting effect, but also in treats for tired and puffy eyes, which are such a widespread challenge. Since all but the most abstemious of us drink plenty of this each day, we wouldn’t say there’s a problem with putting it on the skin, especially as it also has an antioxidant effect.

Calcium silicate Also known as Okenite: an anti-caking ingredient also found in baking powder, so approved for food use. In the beauty world it appears mostly in face powders, because it can be milled extremely finely and absorbs water well.

Calcium sodium borosilicate A thickener, derived from Calcium and Silicates.

Caprylic/Capric Triglyceride A fatty acid derived from palm, coconut and other plant oils (although it can also be obtained from cow’s or goat’s milk). Also used as a food additive.

Caprylyl glycol A skin-conditioning agent that can be derived from plants, or synthesised. It’s often used as a preservative alongside phenoxyethanol and chloroxylenol.

Carbomer A synthetic thickening agent used to create gel-like products, which according to the most recent info we’ve seen has no known toxicity.

Carboxylic acid A group of ingredients which includes many fatty acids as well as amino acids, Benzoic acids and Salicylic acids.

Castor oil benzoate An ester of Benzoic acid and Castor oil (Ricinus communis), which is soothing to skin.

Castor oil sodium hyaluronate spheres Basically derived from Sodium Hyaluronate and Castor oil (see above), a very useful moisturising and soothing oil.

Centella Asiatica (hydrocotyl) extract Derived from the gotu kola plant – an umbelliferous plant a bit like celery, with wound-healing properties – this has no known toxicity.

Ceramide 3 Ceramides are naturally present in the skin and play an important role in forming a protective barrier, to prevent water loss. They also give skin a feeling of softness. Ceramides can be found in nature (from animals or plants), although it is hard to isolate the pure versions needed for cosmetic use; they are also complicated to synthesise, although be aware that the ingredient Ceramide 3 is a synthetic version.

Ceteareth-20 A synthetic fatty alcohol that is widely-used to thicken ingredients and stop them from separating. It’s not considered suitable for use on injured or damaged skin, and there are reservations about its use in products for use around the lips and eyes – although the single product that it appears in, in our book, is a body scrub, so that conforms to those guidelines. Ingredients like this – created by a process called ‘ethoxylation’ – can in some circumstances be contaminated to produce 1,4-dioxane – a carcinogen – although that’s not to say they will be, provided effective controls are in place.

Ceteareth-33 A lubricating, emollient ingredient – find it in hand creams, cleansers, moisturisers and SPF products – derived from Cetearyl alcohol; see also Polyethylene glyol under ‘Phere.

Cetearyl alcohol – very widely used in natural cosmetics as it has no known toxicity; it can be derived from coconut, or synthesised. It’s used as an emollient, an emulsifier (to help ingredients blend) and as a thickener.

Cetearyl glucoside Created by the condensation of Cetearyl alcohol (see above) with glucose. No known adverse effects.

Cetearyl octanoate An ingredient created from Cetearyl alcohol (see above) and fatty acids from palm oil. No known toxicity.

Cetearyl olivate An ingredient created from Cetearyl alcohol (see above) and fatty acids from olive oil. No known toxicity.

Cetearyl wheat straw glycosides Rather like the couple of ingredients listed above, an ingredient created by the reaction of Cetearyl alchol (see above) with the sugars derived from wheat straw.

Ceteth-2 This is what you get when you mix Lauryl, Stearyl and Oleyl alcohols with Ethylene oxide, creating oily liquids or wax-like solids. Used to create smooth formulations.

Cetrimonium chloride Very popular in hair conditioners and styling products, this is a synthetic ingredient. See: Quaternary ammonium compound under ‘Q‘ – here. It can be irritating and sensitising, at the very least, and ideally the products it appears in should be rinsed off the skin.

Cetyl acetate Most often found in hand lotions, this is derived from Cetyl alcohol and Acetic acid (vinegar is about 4 to 6 per cent Acetic acid, and it also occurs naturally in apples, cocoa, oranges, pineapples, etc.).

Cetyl alcohol Very widely used natural cosmetics – everything from baby lotions to antiperspirants and foundations, this can be naturally derived or synthetic. In many ingredients, the word ‘alcohol’ can be confusing – because they’re not related to ethyl alcohol at all, and so doesn’t have a characteristic drying effect. (On the contrary, it’s an emollient, and also helps to stabilise products.

Cetyl esters Derived from Cetyl alcohol – see also the entry for Esters under ‘E‘ – here.

Cetyl ethylhexanoate A synthetic ester of Cetyl alcohol (see above) and 2-ethylhexanoic acid. (Well, you wanted to know!) In animal tests (which we are deeply against), it has been found to be an irritant. It’s a replacement for Spermaceti wax, which comes from whales – which is definitely not something we’d want to find in a cosmetic (although it was very popular, decades ago…)

Cetyl PEG/PPG-10 Also known as Cetyl dimethicone; dimethicone is a silicone derived polymer which gives a silky feel to skin. (There is some thought that Dimethicone can be pore-blocking, because it’s film-forming.)

Cetyl ricinoleate Made from a combination of natural fatty acids (coconut oil) and sugars. It acts as a stabiliser, giving the product a natural consistency. No known adverse effects.

Chlorphenesin An alcohol used as a germicide. Considered ‘low hazard’ by the Environmental Working Group’s Skin Deep Cosmetic Safety Database.

Cholesterol Occurs naturally in animal fats and oils, egg yolks, etc. and is useful as a lubricating ingredient in a wide range of moisturisers, shine-boosters and shampoos etc.

Chromium hydroxide green (CI 77289) A mined mineral pigment derived from chromium.

Chromium oxide greens (CI 77288) As above.

CI 14700 (also known as FD&C red 504) This coal-tar derived colourant used to be approved for food, although that’s been withdrawn. Considered ‘low hazard’ by the Environmental Working Group’s Skin Deep Cosmetic Safety Database.

CI 15850 (also known as D&C red 6 lake) A synthetic red disodium salt of an Azo dye.

CI 15850:1 (Red 7 lake) See above, but derived originally from a calcium salt. (Red 6 and Red 7 have the same CI number.)

CI 15880 (also known as D&C red 34 lake) Red coloured Azo pigment, allowed in all products except eye products.

CI 15985 (also known as FD&C yellow 6 lake, and as E110, a food colourant that goes by the name of Sunset yellow) A synthetic Azo dye.

CI 16035 (also known as FD&C red 40) Can be derived from animal, plant and synthetic sources, and may be a coal tar derivative; also approved for use in food.

CI 17200 (also known as FD&C red 33) A coal-tar derived colourant; c onsidered ‘low hazard’ by the Environmental Working Group’s Skin Deep Cosmetic Safety Database; it’s allowed in the US in all products except eye products, and in quantities under 3% in lip cosmetics.

CI 19140 (also known as FD&C yellow 5) A coal-tar derived colourant; considered ‘low hazard’ by the Environmental Working Group’s Skin Deep Cosmetic Safety Database. Also known as Tartrazine , which is still widely used in food as a yellow colourant (although pressure groups are campaigning to have it removed because of its links to hyperactivity). Not allowed in eye products in the USA.

CI 42090 (also known as FD&C acid blue 9). Ammonium salt. Considered ‘low hazard’ by the Environmental Working Group’s Skin Deep Cosmetic Safety Database.

CI 45380 (Red 22 lake, or Acid red 87) A synthetic red colourant which may cause photosensitivity in some people.

CI 45410 (Red 27 lake) Synthetic red colourant; allowed in all cosmetics except eye products.

CI 45410 (Red 28 lake) See above, Red 27 lake.

CI 47005 (Yellow 10 lake) A synthetic coal tar dye allowed in all products; also in food (E105).

CI 73360 (also known as D&C Red No. 30) A synthetic coal tar dye allowed in all products (except for eye products) on sale in the US.

CI 75470 (also known as Natural Red 4) Carmine, a natural organic dye that is made from the dried bodies of the female insect Coccus cacti which lives on various cactus plants. It has been used as a pigment for millennia, and is one of the most natural dyestuffs. Although not, of course, vegan, it is cruelty-free since only the (already)-dead bodies are used.

CI 75810 Chlorophyllin-copper-complex Basically, from plant chlorophyll (the natural green colourant), together with copper.

CI 77120 A white mineral (although this can also be artificially produced). See also Barium Sulfate under ‘B’here.

CI 77007 Ultramarine, a mined blue mineral.

CI 77288 Chromium oxide greens, from chromium (a mined mineral).

CI 77410 Ferric ammonium ferrocyanide, or iron oxide.

CI 77491 Ferric oxide, or red iron oxide.

CI 77492 Ferric oxide, or yellow iron oxide.

CI 77499 Ferric oxide, or black iron oxide.

CI 77510 Ferric ferrocyanicide, also known as iron blue – a blue pigment with no known toxicity.

CI 77713 Magnesium carbonate – a natural mineral which can also be produced artificially and used as a white colourant.

CI 77742 Manganese violet, a mined mineral.

CI 77891 Titanium dioxide, a mined mineral.

Cinnamal Occurs naturally in cinnamon bark, cassia bark extract and root oils; it is one of the most common allergens, and must be listed as a separate fragrance component on labels because of this.

Cinnamyl alcohol Occurs naturally in Balsam of Peru, cinnamon leaves and hyacinth flowers – and smells deliciously of hyacinth. Has to be listed as a separate fragrance component on labels because it is known to trigger sensitivity in some people.

Citral Used in perfumes, colognes and soaps because of its lemony, verbena-y scent, this occurs naturally in grapefruit, lemon and lime oils; it is one of the most common allergens, and must be listed as a separate fragrance component on labels because of this.

Citric acid Derived from citrus fruit, it’s used as a preservative or to adjust pH balance. This is an ‘AHA’ (alpha-hydroxy acid) and can cause sun sensitivity if used in high quantities.

Citronellol Naturally occurring component of essential oils of rose, lemon oil, lemongrass oil; it can be skin-sensitising, and must be listed as a separate fragrance component on labels because of this.

Citronellyl methylcrotonate A synthetic ester of Citronellol (see above) and 3-methylcrotonic acid.

Cocamide DEA Widely-used derivative of coconut oil, used as a foam booster and thickener. Can be skin irritating, and, in addition, is one of the family of ‘alkyloamides’, which can combine with formaldehyde-releasing preservatives in cosmetics, with concerns that they may form carcinogens. However, there are a lot of ‘cans’ and ‘coulds’ in that sentence, and of all the alkyloamides, this is generally considered the least problematic.

Cocamide MEA See above.

Cocamidopropyl betaine Useful in hair conditioners because it has an anti-static effect, and as a surfactant (cleansing ingredient). Derived from Cocamide (from coconut) and Glycine betaine (generally from wheat or sugar beet). It is hoped that by allowing the use of this ingredient in Soil Association-certified products, this will encourage production of an organic surfactant – which will make it far easier to produce a certified organic shampoo than is currently possible.

Coco glucoside A cleansing ingredient obtained by the condensation of coconut alcohol with glucose (from sugar).

Copper gluconate This pale blue, ultra-fine powder (derived from copper) is used as a food colouring as well as to colour cosmetics.

Coumarin Fragrance ingredient found in plants and derived from the animo acid phenylalanine, this delivers a fragrance of ‘new-mown hay’; it can be skin-sensitising, and must be listed as a separate fragrance component on labels because of this.

Cyclomethicone A silicone ingredient with a ‘dry’ finish, popular in deodorants, suntan gels, eye make-up removers, lipsticks etc. Synthesised from silica, which occurs in 12% of all rocks (sand, for instance, is a silica). No known toxicity although, because these are film-forming and water-repellant, they can block pores.

Cyclopentasiloxane A silicone fluid used in deodorants, sunblocks, haircare and skincare, and increasingly in conditioners as it makes hair easier to brush without breakage. (This emollient is also used as part of silicone-based personal lubricants!)