K18 Leave-in molecular repair hair mask

Main solvent and base of the formula. It helps dissolve and distribute the conditioning, protein, and preservative ingredients so the product can spray or spread evenly through hair.

Very low concern in normal hair-care use. Main issue is simply that it adds no direct conditioning on its own.

Also known as: Water

Acts as a fast-evaporating solvent, which can help the product dry quickly and improve spray feel. In hair products, it can also help deliver lightweight actives without making the formula heavy.

Can be drying or irritating for very dry, damaged, color-treated, or sensitive scalps, especially if used often. This is a well-established practical concern rather than a rare issue.

dry, brittle, or sensitive hair/scalp

Also known as: Denatured Alcohol

Humectant and solvent that helps retain moisture and keep the formula from feeling too dry. In a hair product, it can improve slip and help distribute actives more evenly.

Generally well tolerated, but some people with sensitive skin or scalp may find it irritating, especially in leave-on products. This is a routine caution.

sensitive scalp

Also known as: 1,2-Propanediol

Fatty alcohol that adds slip, softness, and a creamier feel. It helps reduce roughness and makes hair easier to comb, especially on dry or textured hair.

Usually very well tolerated and is not the same as drying alcohols like ethanol. Rarely, very sensitive scalps may react to any rich conditioning base.

Light emollient that improves spreadability and gives hair a smoother, less tacky feel. It can help reduce the dry, stripped sensation from alcohol-heavy formulas.

Generally low risk in hair care. The main practical issue is that it may feel too light to provide lasting softness on very dry hair.

very dry hair needing heavier conditioning

Likely a waxy emollient/texture aid that adds body, slip, and a more polished feel to the formula. In hair products, this can help reduce roughness and improve combability.

Generally low concern in rinse-off or low-use hair products, though very rich ester systems can weigh down fine hair. Evidence is routine for this ingredient class.

fine hair prone to heaviness

Also known as: cetyl esters wax

Primary conditioning agent and anti-static ingredient. It helps detangle hair, reduce frizz, and improve wet combing, which is especially useful for damaged or curly hair.

Generally safe in hair products, but it can irritate very sensitive scalps if overused or left on too long. This is a standard quaternary conditioning agent with well-known use patterns.

sensitive scalp

Solubilizer/emulsifier that helps fragrance and other oil-like ingredients stay mixed in the water-based formula. It improves product stability and helps the spray or lotion stay uniform.

Generally low concern, though it can contribute to irritation in very sensitive users when combined with fragrance. The fragrance-related tag reflects its common use in fragranced systems.

very sensitive scalp

Likely a bioactive peptide intended to support hair strength, fiber quality, or scalp signaling. In practical terms, it is usually included for a targeted 'treatment' claim rather than immediate cosmetic feel.

Generally expected to be low risk at cosmetic use levels, but peptide efficacy in hair products can be limited by delivery and concentration. Evidence for hair benefits is often product-specific and not always robust.

Also known as: sh-oligopeptide-78

Film-forming protein that can temporarily improve hair feel, reduce breakage during combing, and add a fuller or stronger sensation. It is most useful for damaged, porous, or fine hair that benefits from extra structure.

Generally safe, but it is a known wheat-derived allergen for some people and can be an issue for very sensitive users. This is a well-established labeling concern rather than a common problem for most users.

wheat allergy or protein-sensitive hair

Thickener and texture modifier that helps the formula feel more substantial and can slightly improve hair body. It may also reduce a watery or overly slippery feel.

Low safety concern in normal use. As with other wheat-derived ingredients, people with wheat allergy may prefer caution, although the allergenic risk is usually lower than with intact wheat proteins.

wheat allergy

Fast-evaporating solvent that can help the product dry quickly and improve spray performance. It may also help dissolve certain ingredients and reduce residue.

Can be drying and irritating, especially on a sensitive scalp or already-dry hair. This is a well-established concern for leave-on products with noticeable alcohol content.

dry, damaged, or sensitive hair/scalp

Also known as: isopropanol

Antioxidant that helps protect the formula's oils and fragrance components from oxidation. In hair care, it may also provide a small supportive benefit to scalp and hair lipids.

Generally well tolerated. Rare contact sensitivity can occur, but this is uncommon in cosmetic use.

Also known as: Vitamin E

Preservative that helps prevent microbial growth in this water-containing product. This is important for safety and shelf life, especially in leave-on formulas.

Generally safe at permitted cosmetic levels, though some very sensitive users may notice irritation. This is a well-established preservative with broad use.

very sensitive scalp

Preservative that helps inhibit yeast and mold growth, supporting product stability. It is often used alongside other preservatives in water-based formulas.

Generally low risk, but it can sting or irritate compromised skin or scalp in some users. This is a routine preservative caution.

sensitive or compromised scalp

pH adjuster that helps keep the formula in a range that is more compatible with hair and scalp. A slightly acidic pH can help hair feel smoother and look shinier.

Usually safe, but it can sting if the scalp is irritated or if the formula is too acidic. This is a standard pH-adjuster consideration.

irritated scalp

Also known as: Vitamin C Acid

Adds scent and masks base odors from solvents and conditioning agents. In a hair product, fragrance mainly affects user experience rather than hair performance.

Common source of irritation or allergy, especially for sensitive scalps or people with fragrance sensitivity. This is a well-established concern for fragranced leave-on products.

fragrance-sensitive users

Also known as: Parfum

Fragrance component that contributes a floral, rosy note. It is included for scent rather than hair treatment.

Known fragrance allergen and a common sensitizer in leave-on products. People with fragrance allergy or very reactive skin should be cautious.

fragrance-allergic or sensitive users

Fragrance ingredient that contributes a fresh floral scent. It does not provide meaningful hair conditioning.

Known fragrance allergen, especially after oxidation in stored products. Sensitive users may react even at low levels.

fragrance-allergic or sensitive users

Fragrance ingredient used to add a sweet floral note and round out the scent profile. It is included for odor and sensory appeal.

Can trigger fragrance sensitivity in some users, though it is commonly used within regulated limits. This is a routine fragrance-allergen caution.

fragrance-sensitive users

Also known as: hexyl cinnamaldehyde

Functions as a preservative and also contributes a mild aromatic note. In this formula it helps protect the product from contamination while supporting the fragrance system.

Generally safe at cosmetic levels, but it is a recognized fragrance allergen and can irritate very sensitive skin. This is a well-established caution.

fragrance-sensitive or reactive users

Fragrance ingredient that adds a sweet, floral, slightly balsamic note. It mainly supports the scent profile rather than hair performance.

Generally low concern at very low fragrance levels, but it can still contribute to fragrance sensitivity in reactive users. Evidence is routine for fragrance use, with irritation risk depending on total blend.

fragrance-sensitive users

Also known as: amyl salicylate

Fragrance component that can contribute an almond-like, cherry-like note. In this product it is mainly for scent and odor masking.

Generally low concern at trace fragrance levels, but it can be irritating for very sensitive users and adds to the overall fragrance allergen burden. Evidence is routine for fragrance use.

fragrance-sensitive users

Also known as: benzaldehyde