COCAMIDOPROPYL BETAINE

We present two cases of allergic contact dermatitis caused by the amphoteric surfactant coco betaine, a constituent of clobetasol propionate (CP) shampoo, despite the low allergenic potential of CP shampoo formulations. The patients were Japanese males, aged 49 and 52 years, with severe atopic dermatitis, who had been treated with oral cyclosporine for several years. Patch testing revealed that only coco betaine 1% aq. showed a clearly positive reaction in both cases, whereas the patch test results of CP shampoo, cocamidopropyl betaine, and lauramidopropyl betaine were positive in one case and doubtful in the other. In cases of recalcitrant scalp dermatitis, it is necessary to consider the possibility that it is being caused by the topical medication used to treat it, and that the "active" ingredient may not be the culprit.

Cocamidopropyl betaine (CAPB) is an amphoteric surfactant that is commonly used in skin care materials. Although there are many reports about the safety of CAPB, there is limited data about its physical effects on the stratum corneum. Porcine stratum corneum sheets were soaked in 5% or 10% CAPB solution (pH 4.0, 7.0 or 9.0) for up to 60 min at room temperature. After rinsing with distilled water, the properties of the porcine stratum corneum sheets were analyzed using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Sixty min of treatment with 5% CAPB or 10 min of treatment with 10% CAPB did not induce any peak shift at any pH. However, 60 min of treatment with 10% CAPB induced peak shifts of CH2 asymmetric stretching vibration and NH stretching vibration to higher wavenumber values. Although all pH solutions induced those peak shifts, the higher pH solutions caused larger peak shifts. However, 24 hrs treatment with 10% CAPB did not cause swelling at any pH. These results indicate that a long time and/or higher dose of CAPB affects the surface of stratum corneum, but this effect may not be caused by the regular use of CAPB in skin care materials.

Sodium lauryl sulfate (SLS) has been included as an irritant control in the baseline patch test series of the German Contact Dermatitis Research Group (DKG) for two decades, although its diagnostic value remains controversial. To evaluate the strengths and limitations of SLS as an irritant control in patch testing. We retrospectively analysed data from 43 478 consecutive patients patch tested with 0.25% SLS aq. and 189 allergens within the IVDK network. SLS reactions were graded from 1 (weak) to 5 (strong). Associations between SLS reactivity and allergen-specific responses were examined. Overall, 22.4% of all patients reacted positively to SLS, most with weak erythema (SLS 1). Stronger SLS reactions (SLS 2-5) were associated with male sex, age ≥ 40 years, occupational dermatitis and hand dermatitis. Positive SLS reactions correlated with several allergens of high irritative potential, notably cocamidopropyl betaine, formaldehyde, sorbic acid and diphenylguanidine. In contrast, plant-derived allergens showed weak or inconsistent associations. Importantly, grading SLS reactions (1-5) did not improve diagnostic discrimination compared to a simple positive/negative classification. While SLS can indicate skin irritability for certain allergens, it is not a universal marker. Our large-scale analysis supports binary SLS classification and provides a robust evidence base for the ongoing debate on whether and how irritant controls should be used in patch testing.

The aim of this study was to evaluate the surface hydrogen potential (pH) values of children's soaps to identify those with a pH closer to the physiological one (5.0-5.5) and describe the most prevalent surfactants in the sample. This was a observational, analytical, cross-sectional, and quantitative study that included 96 cleansing products intended for children's or sensitive skin, available at over-the-counter sales points in a Brazilian capital. The pH of the samples was measured after dilution to 1% in distilled water. A total of 34 bar soaps and 62 liquid soaps (including 20 syndets) were analyzed. Descriptive statistics and Student's t-test were used to analyze the differences between the groups, with a minimum significance level of 5%. The surfactants present in the products were listed, and the most prevalent were identified. The pH of the products ranged from 4.54 to 11.01, with a mean of 7.80±1.90. The pH levels differed between the liquid and bar formulations (4.54-8.00 vs. 8.01-11.01, respectively; p<0.001). The syndets had pH values closer to the physiological range (4.99-7.78), with lower values when compared to liquid soaps (p<0.001). The most prevalent surfactant in the sample was cocamidopropyl betaine. Bar soaps do not have a pH suitable for children's skin cleansing, whereas liquid soaps, particularly syndets, have a pH closer to the physiological range. Knowledge of the pH values of children's cleansing products by health professionals and caregivers is important, given the wide variety found in this study and the lack of reliable information on the packaging of most products. Avaliar os valores de pH dos sabonetes infantis a fim de identificar aqueles com pH mais próximo ao fisiológico (5,0–5,5) e determinar os surfactantes mais prevalentes na amostra. Estudo observacional, analítico, transversal e quantitativo com 96 produtos de limpeza destinados à pele infantil ou à pele sensível, encontrados em pontos de venda livre de uma capital brasileira. Procedeu-se à mensuração do pH das amostras após diluição a 1% em água destilada. Foram analisados 34 sabonetes em barra e 62, líquidos (sendo 20 syndets ). Além da estatística descritiva, utilizou-se o teste t de Student para analisar as diferenças entre as médias de pH dos grupos, com nível de significância mínimo de 5%. Realizou-se, também, listagem e classificação dos surfactantes. O pH variou de 4,54 a 11,01, com média de 7,80±1,90. Os níveis de pH diferiram entre as formulações líquida e em barra (respectivamente 4,54–8,00 vs. 8,01–11,01; p<0,001). Os syndets tiveram os valores mais próximos ao pH fisiológico (4,99–7,78), sendo os valores menores quando comparados aos demais sabonetes líquidos (p<0,001). O surfactante mais prevalente na amostra foi cocamidopropil betaína. Os sabonetes em barra não possuem pH adequado para cuidados da pele infantil, sendo os líquidos, em especial os syndets , os que apresentam pH mais próximo ao fisiológico. O conhecimento dos valores de pH dos produtos de limpeza infantil por profissionais de saúde e cuidadores é importante, dada a grande variedade encontrada neste estudo e a falta de informações confiáveis nas embalagens da maioria dos produtos.

Cosmetic formulations are complex mixtures of ingredients that must fulfill several requirements. One of the challenges of the cosmetic industry is to find natural alternatives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and form supramolecular networks. The impact of low-molecular-weight gelators on the environment is reduced as they are highly biodegradable. Thus, the behavior of solutions containing Boc-L-Dopa(Bn) 2 -OH, an LMWG, together with ten different anionic surfactants, was studied to understand if the LMWG may act as a rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. An amphoteric surfactant, cocamidopropyl betaine (CAPB), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. In most cases, the addition of the gelator at only a 1% w / v concentration induces the gelification or an increase in the viscosity of the solutions, thus showing that this molecule is also able to self-assemble in complex mixtures.

Personal care product usage is becoming increasingly prevalent among men due to evolving attitudes surrounding appearance, aging, and masculinity. Given the specific characteristics of male skin compared with female skin and varying product use between males and females, the occurrence of allergic contact dermatitis (ACD) due to men's personal care products needs to be better characterized. The purpose of this review was to identify specific product types and ingredients causing ACD in males. PubMed search was conducted from conception to present day using keywords pertaining to male personal care product use. Case reports, case series, and case-control studies reporting a diagnosis of ACD due to a personal care product ingredient were analyzed. Products resulting in ACD included aftershave, cologne, deodorant, hair dye, hair gel, hair loss preparation, hand cleanser, lip balm, moisturizer, shampoo, and sunscreen. Although >90 allergens resulting in ACD were identified, the 5 most common allergens included para-phenylenediamine, minoxidil, musk ambrette, methylisothiazolinone, and cocamidopropyl betaine. Following this review, clinicians should be better able to recognize men's personal care products that commonly result in ACD, as well as specific allergens present across multiple product types. Doing so will lead to improved diagnosis and treatment of ACD due to personal care product usage in men and, in doing so, guide both clinical practice and future investigation in this area.

To examine the apparent increase in plasma cell lesions of the oral cavity over the course of the past two decades and to propose a possible explanation and therapeutic approach for a subset of these cases. Data from cases evaluated at the University of Iowa Surgical Oral Pathology Laboratory (UI-SOP) between July 2003 and May 2024 were retrospectively reviewed to analyze demographics, clinical presentations, and trends in the incidence of these lesions. Additionally, a subset of clinical cases seen at the Oral Pathology Clinic from 2023 to 2024 was examined to explore a potential association with the use of cocamidopropyl betaine (CAPB)-containing toothpaste. A total of 61 cases were retrieved from UI-SOP archive and analyzed. An increase in the histopathologic diagnoses of oral plasma cell lesions was observed. The clinical case series would seem to indicate CAPB as a possible additional chemical associated with plasma cell gingivitis. Eliminating the CAPB-containing toothpaste appeared to be a predictable reason for resolution of the gingival/mucosal phenotype in multiple patients. Further collection of cases in a controlled prospective manner may be helpful in confirming the association.

Preservatives are primarily used for their antimicrobial properties and form an important component of food, cosmetic, and drug formulations. The efficacy of preservatives depends on various factors, which include the bacterial membrane composition and the interaction between components of a specific formulation. Molecules such as phenoxyethanol (POE), caprylylglycol (CPG), and methylparaben (MEP) are widely used as preservatives in the food and cosmetic industries; however, a molecular understanding of their interactions with surfactants and the kinetics of membrane partitioning remains unexplored. In this study, coarse-grained molecular dynamics simulations were carried out to evaluate and quantify the kinetics of membrane partitioning for preservatives and surfactants in the Escherichia coli inner phospholipid membrane. We propose a mass-transfer-based model to determine membrane partitioning kinetics. Faster kinetics were observed for first-order partitioning of POE and MEP (τ ∼ 0.01 μs) when compared with zeroth-order kinetics (τ ∼ 0.1 μs) for CPG. In contrast, surfactants such as sodium laureth sulfate (SLES) and cocamidopropyl betaine (CAPB) follow zeroth-order membrane partitioning kinetics with significantly higher time constants (1.5-10 μs). Interestingly, zeroth-order kinetics occurred when micellar aggregates were present, and the rate-controlling step was the slow rate of release of single molecules from the aggregate, in comparison to faster membrane uptake kinetics. Using a sequential micellar breakup model with single surfactant release dynamics, we analytically recover this unique zeroth-order membrane partitioning kinetics. In preservative-surfactant mixtures, the kinetics of preservative partitioning were found to decrease by a factor of 2-10. Significantly, the equilibrium membrane saturation coefficients for both preservatives and surfactant remained invariant in the mixtures due to the wide separation of partitioning time scales for the surfactants and preservatives. The kinetic models developed in this study can be used to quantify membrane partitioning of preservatives and understand the influence of surfactants in specific formulations.

Abstracts: Background: Hair dye-related allergic contact dermatitis (ACD) is a common problem among both consumers and professionals. The main sensitizers are aromatic amines such as para-phenylenediamine (PPD) and toluene-2,5-diamine (TDA), which can also cross-react with chemically related compounds. Objective: To analyze patch-test results from patients with suspected hair dye-related ACD, focusing on the prevalence of sensitization to hair dye allergens, cross-reactivity patterns, and occupational differences. Methods: We retrospectively reviewed 666 patients patch-tested between 2005 and 2023 at the Patch Test Clinic of Andreas Sygros Hospital, Athens, Greece. All patients were tested with the European baseline and extended hairdresser series. Results were evaluated according to the International Contact Dermatitis Research Group and European Society of Contact Dermatitis criteria. Logistic regression was used to calculate odds ratios for co-sensitization, adjusted for sex and age. Results: Overall, 82.4% of patients reacted to at least 1 allergen, with a median of 3 positive reactions. PPD was the most frequent allergen (47.9%), followed by TDA (35.9%) and nickel (41.1%). Significant co-sensitization was observed between PPD and several chemically related compounds, including 4-aminophenol, 3-aminophenol, benzocaine, textile dyes, hydroquinone, and pyrogallol ( P < 0.001). Similar associations were observed for TDA. Hairdressers were younger (mean 32.2 vs 40.7 years, P < 0.001) and had predominantly hand dermatitis (62.9%). Patients reacting to multiple hair dye components were significantly more likely to be sensitized to PPD. Co-sensitization between PPD and cocamidopropyl betaine likely reflected cosmetic co-exposure rather than structural cross-reactivity. Conclusions: PPD and TDA remain the dominant sensitizers in hair dye-related ACD, with strong cross-reactivity to aminophenols, benzocaine, and textile dyes. Extended patch testing is essential for accurate diagnosis, as 7% of para-amino-compound-sensitized patients would be missed by PPD testing alone. Occupational exposure and multi-allergen sensitization highlight the need for safer formulations and preventive strategies in hair dye use.

Environmental variability (including fluctuations in water hardness, pH, and temperature) can markedly affect the performance and stability of surfactants in cosmetic formulations. This study systematically evaluates the environmental robustness of three representative surfactants-Sodium Lauryl Ether Sulfate (SLES, anionic), Cocamidopropyl Betaine (CAPB, amphoteric), and Decyl glucoside (non-ionic)-with a focus on the sustainable performance of decyl glucoside in diverse conditions. Physicochemical parameters including surface tension, critical micelle concentration (CMC), viscosity, and physical stability were analyzed across hardness levels (0-400 mg per L CaCO 3 ), pH (5.5-9.0), and temperatures (4-40 °C). SLES exhibited pronounced sensitivity to hard water, showing increased surface tension (32.5 → 36.8 mN m -1 ) and elevated CMC (0.25 → 0.45 mM), resulting in precipitation and reduced viscosity. CAPB demonstrated moderate resilience (CMC 0.15-0.24 mM), while decyl glucoside maintained stable physicochemical behavior (CMC ≈ 1.0 mM) regardless of ionic or thermal stress. Statistical analyses (ANOVA, p < 0.01) confirmed significant environmental effects on ionic surfactants but not on decyl glucoside. Mechanistic interpretation based on ion-micelle interactions revealed that the non-ionic structure of decyl glucoside prevents cation binding and aggregation, ensuring consistent interfacial activity and viscosity. The results highlight decyl glucoside's superior environmental stability, biodegradability, and formulation compatibility, positioning it as an ideal candidate for next-generation eco-friendly cosmetics. This work advances the understanding of surfactant-environment interactions and supports sustainable formulation design aligned with green chemistry principles.

Given the underdevelopment and sensitivity of babies' eyes, frequently used baby bath products have garnered attention for their ocular irritation safety. The selection and application of raw materials are key factors. We tested 39 commercial baby bath products for ocular irritation safety and proposed a novel evaluation method using the "Risk Attention Index" to analyze formulation risk factors. The ocular irritation potential of 39 commonly used raw materials under typical usage conditions was investigated via animal and cell models. Results showed over 20% of commercial products had safety risks. Surfactants like cocamidopropyl betaine (CAPB), sodium laureth sulfate (SLES), and sodium lauroamphoacetate (SLA) had the highest "Risk Attention Index", requiring special attention. Some fragrance components were also potential irritants. Combining SLES with panthenol, maltooligosyl glucoside/hydrogenated starch hydrolysate, and Tween ® -28 could significantly reduce its irritation in an animal model. The same ingredients from different sources led to inconsistent irritation results. This suggests that manufacturing processes of raw materials, in addition to their chemical properties, concentration, and combination methods, all influence the ocular irritation potential. This study provides key scientific evidence for assessing ocular irritation and developing low-irritation formulations in baby bath products, thereby enhancing product safety.

The home and personal care industry is evolving toward more sustainable and environmentally friendly ingredients. Rinse-off personal care products rely on formation of polymer-surfactant complexes to drive deposition of benefit agents (e.g., conditioning oils, fragrances, etc.) onto the skin or hair. The most used natural polymers for this purpose are cationic guar (catGuar) and cationic hydroxyethyl cellulose (catHEC), and the complexation of these polymers with surfactants has been rigorously characterized. Various gaps still exist with these polymers, specifically low biodegradation and undesirable aquatic toxicity profiles. Modified dextran offers an exciting solution as a biodegradable polysaccharide with a high natural origin content. This paper aims to compare the morphology of polymer-surfactant complexes formed between a cationic dextran (catDex) polymer with mixtures of sodium lauryl ether sulfate (SLES) and cocamidopropyl betaine (CapB) to the morphologies of complexes formed between catGuar or catHEC and the same surfactants. Solutions were designed to mimic industrially relevant shampoos. Through a suite of complementary techniques, unique nanometric sized complexes were observed to form between catDex-SLES/CapB compared to the widely reported micrometer-sized coacervates (liquid-liquid phase separation) or precipitates (liquid-solid) formed in catHEC or catGuar-SLES systems. Using a quartz crystal microbalance with dissipation, the adsorption behavior of the catDex-SLES/CapB is characterized on a silica-coated sensor. The results show deposition throughout the dilution regime for catDex-SLES/CapB where the highest deposition is recorded with the undiluted rinsing formulation. This contrasts with catHEC-SLES/CapB and catGuar-SLES/CapB where the highest deposition is recorded in phase-separated regimes. This result was extended to performance testing on hair, confirming that the unique complexes formed by catDex can drive remarkably high levels of silicone deposition from rinse-off personal care products. This innovative approach of utilizing catDex-SLES/CapB complexes could enable design of more sustainable formulations that rely on polycation-surfactant nanocarriers.