K18 Professional Molecular Repair Hair Mask 5 oz
Analysis updated August 2026 · How Scout scores
At a glance
Summary
This hair mask contains beneficial ingredients like Cetearyl Alcohol, K18Peptide™, and Hydrolyzed Wheat Protein, which contribute to hair repair and moisture. However, the presence of denatured alcohol and isopropyl alcohol can be drying and irritating, especially in high concentrations. Additionally, the inclusion of fragrance can cause irritation for sensitive individuals, impacting the overall safety profile of the product.
Key ingredients 21
sh-Oligopeptide-78 (K18Peptide™)Very Good
This peptide is designed to repair and strengthen hair by reconnecting broken keratin chains. It is a key active ingredient in the formulation.
Benefits
Helps to repair and strengthen damaged hair, improving overall hair health.
Hydrolyzed Wheat ProteinGood
Hydrolyzed wheat protein is used to strengthen and moisturize hair. It helps to improve hair elasticity and reduce breakage.
Risks
Potential for allergic reactions in individuals with wheat allergies.
Benefits
Strengthens hair and improves moisture retention.
TocopherolGood
Tocopherol, or Vitamin E, is an antioxidant that helps to protect the skin and hair from damage. It also provides moisturizing benefits.
Risks
Generally considered safe with low risk of irritation.
Benefits
Protects against oxidative damage and provides moisturizing benefits.
Water (Aqua) (Eau)Neutral
Water is a common solvent used in cosmetic formulations. It helps to dissolve other ingredients and provides a base for the product. It does not have any direct benefits or risks.
Benefits
Provides a base for the formulation and helps in the application of the product.
Cetearyl AlcoholNeutral
Standard formulation ingredient — neither beneficial nor harmful at typical use.
Risks
Generally considered safe with low risk of irritation.
Benefits
Provides moisturizing properties and improves the texture of the product.
Dicaprylyl EtherNeutral
Dicaprylyl ether is used as an emollient and skin conditioning agent. It provides a lightweight feel and helps to spread the product evenly.
Risks
Low risk of irritation or adverse effects.
Benefits
Contributes to a smooth application and non-greasy finish.
Cetyl EstersNeutral
Cetyl esters are used as emollients and thickeners in cosmetic formulations. They help to improve the texture and feel of the product.
Risks
Generally safe with minimal risk of irritation.
Benefits
Enhances the texture and spreadability of the product.
Behentrimonium ChlorideNeutral
Behentrimonium chloride is a conditioning agent that helps to detangle and soften hair. It is effective in reducing static and frizz.
Risks
Potential for mild irritation in sensitive individuals.
Benefits
Improves hair manageability and reduces static.
Polysorbate 20Neutral
Polysorbate 20 is an emulsifier that helps to mix oil and water-based ingredients. It is commonly used in cosmetic formulations for its stabilizing properties.
Risks
Low risk of irritation or adverse effects.
Benefits
Stabilizes formulations and improves product consistency.
Hydrolyzed Wheat StarchNeutral
Hydrolyzed wheat starch is used as a conditioning agent and thickener. It helps to improve the texture and feel of hair products.
Risks
Potential for allergic reactions in individuals with wheat allergies.
Benefits
Improves product texture and provides conditioning benefits.
Isopropyl AlcoholNeutral
Standard formulation ingredient — neither beneficial nor harmful at typical use.
Risks
Can cause dryness and irritation, particularly for sensitive skin types.
Benefits
Helps in the quick evaporation of the product, leaving a non-greasy finish.
Citric AcidNeutral
Citric acid is used to adjust the pH of cosmetic formulations. It also acts as a mild exfoliant and antioxidant.
Risks
Potential for irritation in sensitive skin types.
Benefits
Helps to balance pH and provides mild exfoliating benefits.
GeraniolNeutral
Geraniol is a fragrance component that provides a rose-like scent. It is naturally occurring in essential oils but can cause irritation in some individuals.
Risks
Potential for skin irritation and allergic reactions.
Benefits
Contributes to the fragrance profile of the product.
Hexyl CinnamalNeutral
Hexyl cinnamal is a fragrance ingredient that provides a jasmine-like scent. It is commonly used in cosmetics but can cause irritation in sensitive individuals.
Risks
Potential for skin irritation and allergic reactions.
Benefits
Enhances the fragrance profile of the product.
Propylene GlycolBad
Processed additive flagged under Scout's ingredient doctrine.
Risks
Potential for skin irritation, especially in sensitive individuals.
Benefits
Helps to maintain skin hydration by attracting water.
PhenoxyethanolBad
Processed additive flagged under Scout's ingredient doctrine.
Risks
Potential for irritation in sensitive individuals.
Benefits
Helps to preserve the product and extend its shelf life.
Potassium SorbateBad
Synthetic preservative — flagged in daily-use products.
Risks
Low risk of irritation or adverse effects.
Benefits
Prevents spoilage and extends the shelf life of the product.
LinaloolBad
Processed additive flagged under Scout's ingredient doctrine.
Risks
Potential for skin irritation and allergic reactions.
Benefits
Adds a floral scent to the product.
Benzyl AlcoholBad
Processed additive flagged under Scout's ingredient doctrine.
Risks
Potential for skin irritation and allergic reactions.
Benefits
Helps to preserve the product and improve its texture.
Alcohol Denat.Very Bad
Denatured alcohol is used as a solvent and can help other ingredients penetrate the skin. However, it can be drying and irritating to the skin, especially in high concentrations.
Risks
Can cause dryness and irritation, particularly for sensitive skin types.
Benefits
Helps in the quick evaporation of the product, leaving a non-greasy finish.
Fragrance (Parfum)Very Bad
Fragrance is used to impart a pleasant scent to cosmetic products. However, it can cause irritation and allergic reactions in sensitive individuals.
Risks
Potential for skin irritation and allergic reactions.
Benefits
Provides a pleasant scent to the product.
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