Surfactants determine many of the actions personal cleansing products have on the skin, but other ingredients can also have an effect. For example, certain polymers are used in personal cleansing products as formulation aids, to alter skin feel, or are substantive on skin, providing skin-protective properties (104-106). Glycerin is a
humectant ingredient used in many leave-on moisturizers that can also facilitate desmosome degradation (107). But being water soluble, it is difficult to deposit an effective level of glycerin on the skin in the rinse-off context that applies to most personal cleansers. However, glycerin can have other effects when used in personal cleansers. For example, Dahlgren et al. showed that incorporating glycerin into a soap bar improved the product’s perceived moisturization benefit even though clinical endpoints are unchanged (40). As was mentioned earlier, some personal cleansers can now deposit effective levels of petrolatum onto the skin during use. These new petrolatum-depositing cleansers can produce marked improvement in dry skin condition; the prototype hand wash products described earlier are an example. Beyond this, there is evidence that topically applied petrolatum permeates the stratum corneum and improves barrier function (108), and that petrolatum deposited from a body wash can improve lipid bilayer structure in the outer stratum corneum (109) and improve stratum corneum barrier function (110).
Ancillary ingredients can also negatively impact skin condition. Fragrances are widely used in personal cleansing products. These materials often serve a functional role, covering the base odor of other formula components, and enhance product aesthetics and the cleansing experience. However, fragrances are frequently implicated as a cause of contact dermatitis and as a potential triggering factor in disease conditions such as atopic dermatitis. Since manufacturers rarely identify specific fragrances or fragrance components, identifying an offending agent is difficult. Using a cleanser that is labeled as “unscented” or “fragrance-free” does not guarantee that fragrance will not be an issue. Fragrance-free, for example, implies that a product has no perceptible odor, but these products can contain a low level of fragrance, smaller than the amount needed to impart a noticeable scent, to mask the odor from raw materials (111). A complicating factor is that some fragrance-free products contain ingredients such as preservatives or natural oils that provide scent as a secondary function, but that can also be a covert source of dermatitis (112,113).