No. 3 Hair Perfector

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

A preservative and humectant that prevents microbial growth while adding hydration. It is approved in both the EU and US and is graded as low concern in cosmetic assessments. It offers good tolerability across formulation types.

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 blend of cetyl and stearyl fatty alcohols used to thicken lotions and soften skin. It is chemically unrelated to drying alcohols like ethanol, and the CIR expert panel has found fatty alcohols safe as used in cosmetics.

The most well-studied form of topical vitamin C, used as an antioxidant and to support collagen signaling and brighten uneven tone. It is acidic and can sting or irritate sensitive skin, and it oxidizes readily once a bottle is opened, which can reduce its effectiveness rather than create a safety issue.

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.

Retinyl palmitate is an ester of vitamin A used in moisturizers and some sunscreens for mild anti-aging and antioxidant support. Long-term panel reviews of the ingredient have generally found it safe as used, with irritation potential similar to other mild retinoids at typical cosmetic concentrations.

A plant-derived water or extract used mainly as a soothing humectant filler. Evidence for dramatic skin benefits beyond mild hydration and soothing is limited, but it is well tolerated by most people.

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

Technically a liquid wax ester rather than a true oil, jojoba closely resembles skin's own sebum and absorbs without feeling greasy. It is well tolerated across skin types, including acne-prone skin, with no significant irritation or comedogenicity signal in the available data.

A protein fragment that draws water into the hair shaft and is used to strengthen and add body. People with wheat sensitivity or protein allergies should patch-test first, as protein hydrolysates can trigger reactions in those with known sensitivities.

A long-chain quaternary ammonium compound used in rinse-off conditioners and leave-on styling products for conditioning and static control. It is well documented in cosmetic use with a strong safety record.

A fatty alcohol used to soften skin and stabilize creams. Despite the name, it does not dry the skin.

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

A preservative that works by slowly releasing small amounts of formaldehyde to keep microbes from growing in the product. It is a well-documented contact allergen for a subset of users, which is why formaldehyde releasers are worth knowing about even though most people tolerate them fine.

A quaternary ammonium salt used as a conditioning and antistatic agent in hair products. It has been extensively documented as safe in cosmetics when used in typical rinse-off formulations.

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 positively charged conditioning polymer used in shampoos and conditioners to reduce frizz and improve manageability. It is well tolerated and has been safely used in cosmetics for decades.

Tetrasodium EDTA is a chelating agent that binds trace metal ions to keep formulas stable and help preservatives work better. It has circulated online as a supposed "toxic" additive, but decades of safety review support its use at cosmetic concentrations.

Butylphenyl methylpropional, widely sold under the trade name Lilial, was banned from cosmetics in the EU starting March 2022 after being classified as toxic to reproduction based on animal studies. Products made and sold in the EU after that date should no longer contain it.

Methylchloroisothiazolinone is typically used together with methylisothiazolinone in a 3:1 mix and is a well-documented skin sensitizer at higher rates than most preservatives. EU rules now restrict this combination to rinse-off products only, at a low maximum concentration.

A preservative that caused a wave of contact allergy in the 2010s. The EU banned it from leave-on products and tightly limits it in rinse-off ones. A genuine concern, not a myth.

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.

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

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

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.

The sodium salt of benzoic acid, used as a preservative in both foods and cosmetics. Decades of safety review support its use at typical cosmetic concentrations, with mild irritation the main reported issue in sensitive skin.

A nutrient-rich oil pressed from sweet almond kernels, used to soften and condition skin. It is generally well tolerated, though people with tree nut allergies should patch test first, as it can rarely trigger allergic reactions.