The Effectiveness of Synthetic Detergents (Syndets) as Skin Cleanser: A General Approach to Balancing Effectiveness and Skin Sensitivity

Lyka N. | Research Intern

Edited by Pierre Trinh and Maria Fernandez Prato

Date of publishing: 28 January 2024

Syndets, or synthetic detergents, have dramatically changed the production and usage of skin cleansing goods by striking a balance between skin sensitivity and effectiveness. Syndets utilize non-soap synthetic surfactants such as sodium lauryl sulfate (SLS), sodium laureth sulfate (SLES), Alpha-Olefin sulfonate, and Sodium cocoyl isethionate. These compounds reduce irritations, keep the skin nourished, and protect the skin's natural barrier, contrasting with normal soap-based cleansers. Studies have demonstrated their efficacy for individuals with atopic dermatitis (AD), showing reduced lesion severity and improved hydration. In balancing the skin's natural acidity, their pH-friendly product lessens negative side effects like dryness, inflammation, and microbial imbalance. Syndets provide mild yet efficient cleansing, particularly beneficial for people with sensitive skin or dermatological disorders like atopic dermatitis (AD), acne, rosacea, xerosis, and photoaged skin. In this article, our research intern, Lyka Natividad, will highlight syndets' potential as possible substitutes in contemporary skincare by examining their chemistry and dermatological benefits.

Keywords: Synthetic surfactants, Syndets, Skin barrier, Dermatological conditions

What is a syndet, and how does it work as a skin cleanser?

As essential ingredients in skincare (i.e., cleansing products) surfactants and detergents function by reducing the surface or interfacial tension of water and oils, allowing them to mix and be washed away [1]. Syndet cleanser products come in the forms of water-, oil-, and hybrid-based products and are mainly composed of fatty acid isothionates or sulfosuccinic esters [7]. The molecules in this formulation are both hydrophilic (attracts water) and lipophilic (attracts oil), which enables it to remove dirt, oil, and other impurities that have penetrated and settled on the skin. Syndet-based cleansers have increased the cleaning performance of skincare products. Among the types of surfactant-containing cleansers, syndets are necessary for maintaining skin hydration while preserving lipid and protein regions of the skin. Conventional soap-based cleansers work the other way. It usually contains anionic surfactants like sodium stearate, which tend to weaken the skin’s protective layer, among other things, such as the removal of proteins and lipids [2]. By balancing the skin's natural acidity, their pH-friendly product lessens negative side effects like dryness, inflammation, and microbial imbalance. Syndets provide mild yet efficient cleansing, particularly beneficial for people with sensitive skin or dermatological disorders like atopic dermatitis (AD), acne, rosacea, xerosis, and photoaged skin.

Syndet cleansers have non-soap synthetic surfactants that are less irritating to the skin and do not form a soap scum layer, which relevantly aids in skin sensitivity issues. Typically, skin cleansers fall into two types: soap-based and synthetic detergents (syndets). Both types contain at least one surfactant, which is soluble in water and organic solvents [3]. This enables impurities in the skin to be washed away more effectively than water can do alone [4]. The key distinction between soaps and syndets is the ability of syndets to have minimal disruption on the skin’s barrier and microflora [5]. Synthetic detergent cleansers are a ‘crafted blend’ of surfactants and other chemicals [5], which are chemically synthesized from fats, petrochemicals or petroleum, oleochemicals, and alkali. However, soaps tend to be harsher; this is because washing with a bar soap raises the skin’s pH level and strips away essential oils and proteins, leading to skin irritation, tightness, dryness, roughness, scaling, as well as contact dermatitis [6]. Thus, emerging is the demand for the shift to syndets to address and reduce negative effects.?

The chemical processes that are involved include sulfonation, ethoxylation, alkylation, and esterification, depending on the specific product needed [7]. These processes are used to assemble and modify surfactant molecules to enhance their functionality, stability, and performance in these cleansers. To illustrate, sulfonation adds sulfonic acid groups to improve water solubility, while ethoxylation increases the mildness and emulsification properties. The way these are formulated ensures that the synthetic surfactants can effectively do their job of cleansing and remain stable while being stored without jeopardizing the skin's natural barrier.?In addition to surfactants, syndets are also made from water or any suitable organic solvent, such as barrier repair moisturizers, binders and plasticizers, fillers, boosters or enhancers, preservatives, fragrance, and color, as needed [8]. Water and other solvents aid in the spreadability and absorption of the product, enhancing its efficacy and effectiveness [8], and such moisturizers help in hydrating and rehydrating the skin and its barrier [9]. Formulating syndet cleanser products involves adding fillers to improve structural integrity [5], preservatives to aid in microorganism growth prevention, and fragrances and colors are added depending on the necessity, with the two usually only present in soaps due to their capacity to irritate the skin [10]. This also includes extending the product's shelf life.

Syndets’ role in maintaining the skin’s barrier integrity is crucial across all skin types. This constitution and ability are what make syndets the superior choice, as they can be processed to match the pH of the skin, which is slightly acidic around 4.0-6.0 [11]. This results in a minimal change to the skin and its native microflora. It also prevents the swelling of the skin due to its slight acidity, as alkaline conditions potentially weaken corneocytes, allowing bacteria to diffuse and other strains to colonize the skin [12], and therefore, syndets result in less damaging effects on the skin. The mildness of syndets on the skin is crucially important, especially for those with skin sensitivities and diseases [7].?

Skin-nourishing benefits

Syndets are especially helpful for people with atopic dermatitis (AD) because they are mild to the skin while maintaining hydration to the outermost layer of the skin [8]. Syndets maintain lipid and protein structures, lowering bacterial colonization and increasing skin resilience [13], in contrast to conventional soaps that damage the skin barrier and worsen dryness [8,13]. This is due to soap bars removing sebum along with essential lipids (e.g., cholesterol, ceramides, and fatty acids) that impair the skin barrier. The structural integrity of the skin depends on these essential components, wherein, in their absence, a natural process called TEWL (Transepidermal Water Loss) takes place, causing the skin to lose moisture [14]. This makes it more susceptible to allergens, irritants, and infections, resulting in dryness and irritation. Therefore, they need “less abrasive” cleansers because their skin is already too sensitive to outside stimuli, including harsh substances, environmental variables, and hormonal fluctuations. Gentle, pH-balanced cleansers assist in preserving the skin’s barrier, lessen irritation, and avoid causing additional harm [8,11].

The mild and non-comedogenic qualities of syndets are especially advantageous for skin prone to acne [3,8,14]. Without causing irritation or over-drying, which can exacerbate acne [3,8], these cleansers efficiently eliminate extra oil and pollutants.

They are also a popular option for treating acne because of their compatibility with topical therapies [11]. Similar to this, syndets help people with rosacea since they stay away from typical irritants like alcohol and astringents [8], which lowers the chance of making sensitive skin worse. Syndets enhanced with hydrating components, such as free fatty acids, assist in relieving dry skin in situations of xerosis by hydrating the skin while cleansing [8]. Because of this, they work well for treating xerotic skin, particularly in older people or those living in dry conditions. By promoting hydration and barrier repair, syndets with humectants and emollients help people with photoaged or sun-damaged skin with symptoms including roughness and decreased suppleness [8].?

Syndets are especially suitable for those with sensitive skin because of their low irritancy potential, balanced pH, and lack of soap scum formation, providing a relaxing cleaning [3]. Those with weakened barriers or neurosensory sensitivities benefit most from them. Similarly, the non-aggravating characteristic of syndets helps patients undergoing dermatological therapies like chemical peels or retinoids [8]. These cleansers aid in healing by gently cleansing the skin without compromising the compromised barrier.

Syndet’s lipid-preserving properties, moisturizing, and pH-balanced qualities make them an excellent option for daily cleansing, particularly for individuals with specific dermatological requirements or necessities such as 'sensitive’, dry, or compromised skin [8]. Their efficacy in countering dryness and irritation and maintaining the integrity of the skin barrier makes them a better alternative and the safest option as a cleanser for modern skincare routines. Unlike traditional bar soaps, syndets are formulated with synthetic surfactants that are more lenient on the skin and inclined towards the skin’s pH level [8, 14]. These findings support the claims of how it functions to reduce the likelihood of irritation, dryness, and damage to a person’s skin barrier.

The moisturizing ability of syndets due to their free fatty acid structure enhances its claims of hydration while simultaneously maintaining the integrity of the facial skin’s epidermis. Individuals managing skin conditions such as atopic dermatitis (AD), acne, rosacea, xerotic skin, and photoaged skin make Sydnet-containing cleansers a safe bet to use [8]. Furthermore, syndets avoid soap scum, which, when left on the face, exacerbates the skin’s sensitivity. The versatility it offers in different cleanser products can address diverse skin types and condition their value as beneficial and superior to traditional soap-based cleansers.?

Sydnets approach role in improving cleansing performance on facial skin offers a balanced proactivity to skincare on which it combines gentle cleansing providing skin protection, which makes it indispensable in contemporary dermatological and cosmetic care.

Recommendations

Sydnet-based cleansers aren’t harmful and prove otherwise as cost-effective and provide benefits for facial skin, whether short- or long-term. To avoid dry and irritable skin, opt out of traditional soap bars, and it is encouraged to switch to a better alternative. Companies should invest in future research of this kind of product to explore more about the long-term benefits of sydnets on other dermatological specificities. This also includes investing in environmental safety and public awareness campaigns to opt for choices in getting healthier skin and a happier planet!

References

[1] Ertel K. Modern skin cleansers. Dermatol Clin. 2000;18:561–75. doi: 10.1016/s0733-8635(05)70207-2. Available: https://www.sciencedirect.com/science/article/abs/pii/S0733863505702072?via%3Dihub

[2] Abbas S, Goldberg JW, Massaro M. Personal cleanser technology and clinical performance. Dermatol Ther. 2004;17:35–42. doi: 10.1111/j.1396-0296.2004.04s1004.x. Available: https://onlinelibrary.wiley.com/doi/10.1111/j.1396-0296.2004.04S1004.x

[3] Corazza M., Lauriola M.M., Zappaterra M., Bianchi A., Virgili A. Surfactants, skin cleansing protagonists. J. Eur. Acad. Dermatol. Venereol. 2010;24:1–6. doi: 10.1111/j.1468-3083.2009.03349.x. Available: https://onlinelibrary.wiley.com/doi/10.1111/j.1468-3083.2009.03349.x

[4] Greive K. Cleansers and moisturisers: The basics. Wound Pract. Res. J. Aust. Wound Manag. Assoc. 2015;23:76–81. Available: https://search.informit.org/doi/abs/10.3316/informit.309050591704236

[5] Chirani M.R., Kowsari E., Teymourian T., Ramakrishna S. Environmental impact of increased soap consumption during COVID-19 pandemic: Biodegradable soap production and sustainable packaging. Sci. Total Environ. 2021;796:149013. doi: 10.1016/j.scitotenv.2021.149013.? Available: https://www.sciencedirect.com/science/article/pii/S0048969721040857?via%3Dihub

[6] Lambers H., Piessens S., Bloem A., Pronk H., Finkel P. Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int. J. Cosmet. Sci. 2006;28:359–370. doi: 10.1111/j.1467-2494.2006.00344.x. Available: https://onlinelibrary.wiley.com/doi/10.1111/j.1467-2494.2006.00344.x

[7] Friedman M. Chemistry, Formulation, and Performance of Syndet and Combo Bars. In: Spitz L., editor. Soap Manufacturing Technology. 2nd ed. Elsevier; Cambridge, MA, USA: AOCS Press; Urbana, IL, USA: 2016. [(accessed on 11 January 2022)]. pp. 73–106. Available: https://www.sciencedirect.com/science/article/pii/B9781630670658500049

[8] Mukhopadhyay, P. Cleansers and their role in various dermatological disorders. Indian J. Dermatol. 2011;56:2–6. doi: 10.4103/0019-5154.77542. Available: https://journals.lww.com/ijd/fulltext/2011/56010/cleansers_and_their_role_in_various_dermatological.2.aspx

[9] Del Rosso J.Q., Levin J. The clinical relevance of maintaining the functional integrity of the stratum corneum in both healthy and disease-affected skin. J. Clin. Aesthetic Dermatol. 2011;4:22–42. Available: https://pubmed.ncbi.nlm.nih.gov/21938268/

[10] Kuehl B.L., Fyfe K.S., Shear N.H. Cutaneous cleansers. Ski. Ther. Lett. 2003;8:1–4. Available: https://pubmed.ncbi.nlm.nih.gov/12858234/

[11] Luki? M., Panteli? I., Savi? S. Towards Optimal pH of the Skin and Topical Formulations: From the Current State of the Art to Tailored Products. Cosmetics. 2021;8:69. doi: 10.3390/cosmetics8030069. Available: https://www.mdpi.com/2079-9284/8/3/69

[12] évora A.S., Adams M.J., Johnson S.A., Zhang Z. Corneocytes: Relationship between Structural and Biomechanical Properties. Ski. Pharmacol. Physiol. 2021;34:146–161. doi: 10.1159/000513054. Available: https://karger.com/spp/article-abstract/34/3/146/296024/Corneocytes-Relationship-between-Structural-and?redirectedFrom=fulltext

[13] Mukherjee, S. S., Chandrashekar, B. S., & Gaikwad, R. P. (2015). Cleansers: To use or not to. Indian Journal of Paediatric Dermatology, 16(4), 193-197.

[14] Mijaljica, D., Spada, F., & Harrison, I. P. (2022). Skin Cleansing without or with Compromise: Soaps and Syndets. Molecules, 27(6), 2010. https://doi.org/10.3390/molecules27062010