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Published: 3. 4. 2025
Understanding Irritancy Score (Sensitive Skin suitability)
Surfactants are crucial ingredients in many cosmetic products like shampoos, facial cleansers, and body washes. They help the product foam, cleanse, and break down oils, but they can also cause skin irritation. In this article, we'll explore what surfactant irritancy scores are, why surfactants can cause irritation, and how these scores are calculated to help you make informed choices about your skincare products.
What Are Surfactants and Why Do They Cause Irritation?
Surfactants are compounds that reduce surface tension and, as a result, help water and oils mix, which allows them to clean the skin by lifting dirt, excessive sebum, and impurities. However, surfactants can also irritate the skin, especially when used in high concentrations. This irritation occurs because surfactants can strip away the natural lipid barrier of the skin, which is essential for keeping moisture in and harmful substances out. When this protective barrier is compromised, it can lead to dryness, redness, and discomfort, and may also provoke eczema or other undesirable skin conditions (irritant contact dermatitis, rosacea flare-ups) in individuals with sensitive or already-compromised skin.
What Is Irritancy Score?
The surfactant irritancy score measures how likely a mixture containing surfactants is to cause skin irritation. It reflects the combined irritancy potential of all the surfactants in a product, considering factors like:
- Base Irritancy: Each surfactant has a base irritancy score derived from its chemical structure and known skin interaction profile. In the Cosminex framework, this score takes into account factors such as surfactant type (anionic, non-ionic, etc.), chain length (short vs. long), degree of acetylation, whether it is amino-acid based, and several other characteristics.
- Concentration: Surfactants are listed in the ingredient list in order of their concentration in the product. Surfactants that appear earlier in the list are typically present in higher concentrations and are given greater weight in the irritancy calculation.
- Amphoteric Surfactants: These are a special type of surfactant that can de-amplify the irritancy of other surfactants, such as anionic and cationic surfactants. When amphoteric surfactants are present, they can reduce the overall irritancy potential of the product.
How is the irritancy score calculated?
The score is calculated by considering the base irritancy, the concentration (influenced by the position of the surfactant in the ingredient list), and the presence of amphoteric surfactants. These factors are combined into a complex score that measures the product's potential to irritate the skin.
The score itself is not a definitive indicator of whether a product will irritate the skin, as individual skin sensitivities vary.
Why does it matter?
Understanding surfactant irritancy scores is essential for making informed decisions about skincare products, especially for individuals with sensitive skin or conditions like eczema. By checking the irritancy score, you can choose products that are less likely to irritate, helping you protect your skin’s natural barrier and maintain healthy skin.
Final thoughts
Surfactants are powerful cleansing agents, but they can also compromise the skin barrier, especially in sensitive individuals. The Cosminex irritancy score helps you understand not only whether a product might irritate but also why. By analyzing each surfactant’s properties, estimated concentration, and interaction with milder ingredients, you gain a deeper, science-based insight into the formula. With this knowledge, you can choose products that respect your skin and avoid those that only look good on the label.
References:
- 1. Mild and Moisturizing Cleansing Liquids. Cosmetic Dermatology, 2009; 22(6): 310. Available at: https://cdn.mdedge.com/files/s3fs-public/Document/September-2017/022060307.pdf
- 2. Corazza, M., Lauriola, M.M., Zappaterra, M., Bianchi, A., & Virgili, A. Surfactants, Skin Cleansing Protagonists. Dermatologic Therapy, 2009; 22(5): 372-381. Available at: https://pubmed.ncbi.nlm.nih.gov/19614860/.
Surfactants analysis
Relative assumption of treachery based on composition
Benefits by molecular size
From surface protection to deep moisturizing effects
Patented complexes
Identification of proven combinations with guaranteed effects
Order effect
Verification of the effective ratio of substances present in the composition
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