Two-Step Protein Treatment

The base most products are built on. It carries the other ingredients and has no safety concern.

Collagen protein hydrolyzed into smaller peptide fragments used in skincare formulations. It is graded low concern, with very rare reports of sensitization. Those with severe shellfish allergies may want to verify sourcing.

Used in tiny amounts to set a product to skin-friendly pH. No concern at those levels.

A mineral salt used in cosmetics as a humectant and antioxidant. It is the same compound used in food and personal care products, and is well tolerated in both rinse-off and leave-on formulations.

A lightweight humectant and solvent similar in role to propylene glycol, used to carry actives and give lotions a lighter feel. CIR has reviewed it and considers it safe as used in cosmetics.

A widely used preservative, safe at the legal limit of 1% or less. Often the "paraben-free" replacement.

A coconut-derived amphoteric surfactant used to boost foam and mildness in cleansers and shampoos. CIR has reviewed it as safe as used, but it is one of the more established contact-allergy triggers in personal care, usually traced to manufacturing impurities such as amidoamine and dimethylaminopropylamine (DMAPA) rather than the betaine itself. People with a history of eyelid or scalp dermatitis are more likely to react.

An undisclosed scent blend that can contain dozens of components. The single most common cause of cosmetic contact allergy, and the blend is not itemized, so you cannot see what is in it.

A glycerin derivative used as a skin conditioner and preservative booster, often paired with phenoxyethanol to allow lower total preservative levels. It has a low irritation and sensitization profile in safety reviews.

A natural fragrance component found in citrus oils and lemongrass, giving a lemony scent. It is a named EU fragrance allergen that can oxidize into potent contact allergens over time; people with known fragrance sensitivities may react.

A citrus-scented fragrance component. Fine for most, but it oxidizes over time into a known contact allergen, so it must be labelled in the EU.

A synthetic or extracted aromatic aldehyde that mimics vanilla scent. It is a known contact allergen in people with fragrance sensitivities, and oxidation over time can increase allergenicity, making it a watch-if-sensitive ingredient in cosmetics.

Alpha-isomethyl ionone is a violet-scented fragrance material and one of the EU-listed allergens requiring label disclosure. Documented sensitization is more common with this ingredient than with many other listed fragrance allergens.

A more stable, esterified form of vitamin E used as an antioxidant and skin-conditioning ingredient. It is a different substance from the vitamin E acetate implicated in vaping-related lung injury, which involved inhaling the oil, not applying it topically to skin.

A soothing humectant that helps skin and hair look conditioned. Very well tolerated.

A small humectant and solvent molecule that helps other ingredients dissolve and helps skin hold water. It is one of the most studied cosmetic ingredients and is considered safe at the concentrations used in personal care products.

A chelating agent that binds trace metal ions to keep formulas stable and preservatives working properly. It is not a functional skincare "active" and only a very small amount is used, with minimal skin penetration expected.

A humectant that draws water into the skin. One of the best-studied, best-tolerated ingredients in personal care.

A widely used, gentle preservative also common in food. It is generally well tolerated, though it can occasionally cause mild, transient irritation in people with already-compromised or very reactive skin.