Here, you’ll find a list of every ingredient I’ve come across in products I’ve reviewed or featured in this blog and why it’s added to cosmetics. I hope this is both informative and helpful! Sources included at the bottom.
Allantoin: Soothes and conditions skin. Allantoin is an extract from urea, usually plant-derived, but also often synthetic.
Alcohol: Thins otherwise viscous skincare and makeup products (eg. moisturiser or foundation) and destroys the skin’s protective barrier to allow active ingredients to be absorbed. This ingredient is frequently used in cosmetics, but is very damaging for skin. If alcohol (also listed as various forms of ethanol) is high on the ingredients list, then you’re looking at a product best kept away from your skin.
Butylene glycol: Usually added to improve the physical texture of skincare and makeup products.
Carica Papaya fruit extract: Papaya. Chock full of vitamins that are particularly beneficial for skin and fruit acids that can exfoliate skin.
Chamaecyparis Obtusa leaf extract: Hinoki cypress. Extracts from this plant are rich in vitamins (including antioxidants) and there is limited research showing some benefits in increasing cell turnover. Some products use this ingredient instead of water.
Cinnamomum Cassia bark extract: Chinese cinnamon. This ingredient is very high in antioxidants, but also contains compounds that can irritate skin. Be wary of cinnamon in cosmetics if you have sensitive or acne-prone skin.
Citric acid: Acid from citrus fruits, used to alter the pH of cosmetics. It is important for products to have the right pH for their ingredients to work effectively.
Dipropylene glycol: Adds slip to cosmetics.
Disodium EDTA: Water in cosmetics can contain trace elements. This ingredient stops other ingredients from binding with those trace elements, which would alter their function. Despite some hype around avoiding EDTAs, the amounts used in cosmetics have been repeatedly found to be safe, even over the course of a person’s lifetime.
Glycereth-26: Added as an emollient and to thicken products.
Glycolic acid: Alpha hydroxy acid.
Hydroxyethyl urea: Humectant.
Lactic acid: Alpha hydroxy acid.
Lactobacillus: Limited research shows some skin-conditioning benefits.
Methylpropanediol: Used as a solvent and can improve absorption of other ingredients into the skin.
Origanum vulgare leaf extract: Oregano. Contains beneficial vitamins.
PEG-40 Hydrogenated castor oil: Emollient that also improves the physical texture of products.
Phenoxyethanol: Preservative. Particularly well-tolerated by those with sensative skin.
Portulaca oleracea extract: Purslane. Excellent for soothing skin.
Salicylic acid: Beta hydroxy Acid.
Salix alba (willow) bark extract: Many claim this ingredient works the same as salicylic acid on the skin, because it is the origin of modern salicylic acid. However, turning willow bark extract into salicylic acid requires the digestive tract, so these claims are unfounded. However, this ingredient is good for soothing sensitive skin.
Scutellaria baicalensis root extract: Skullcap. Full of antioxidants and good for soothing skin.
Sodium citrate: Preservative with antioxidant effects. Also added to alter the pH of cosmetics.
Sodium hyaluronate: Humectant.
Tromethamine: Used to alter the pH of cosmetic products.
Water: Generally little more than filler.
Fundamentals of Pharmacology (university textbook) by Shane Bullock & Elizabeth Manias