Negative Skin Sensations
Many marketed body-care products are known to cause irritation, usually only in a small sub-population, but can result in a product’s withdrawal. Identifying these populations and the underlying mechanisms that case negative skin sensations is critical. Irritation manifests itself in a number of different ways, but broadly speaking these are either purely visual or purely sensory, or more often both. Visual irritation manifests as changes in the redness, dryness and swelling of the skin, without any sensory consequences, whereas sensory irritation is accompanied by the perception of sting, itch, burn, pain and tightness. Visual irritation accounts for approximately 33% of irritation, with sensory irritation accounting for the remaining 67%. Currently, 70% of women and 50% of men perceive that they have sensitive skin, but this self-perception is known to be highly unreliable.
Irritation is caused by molecules such as alpha hydroxyl acids (AHAs), retinol, perfumes and surfactants. The type of irritation that is caused by these molecules is not uniform and different molecules cause different types of irritation in different populations. This highlights the needs for a multifactorial approach to the study of irritation and a range of capabilities to measure & predict its different aspects.
Negative skin sensations are known to be affected by the irritant molecule itself, overall formulation, global region, ethnic group, body site and genetic factors. Complaints of irritation can also prevent commercialization of new molecules, resulting in the levels of actives that are known to be effective having to be reduced in formulations – even though consumer complaints may not reflect a true population response. With ~70% of women and 50% of men perceiving that they have ‘sensitive skin’, and around 65% of women believing that this is caused by a reaction to a product, it is imperative that companies making such products know about the neuroscience of negative skin sensations. Our knowledge of skin neurobiology and our understanding of the receptors that mediate irritation, pain and pleasure have increased dramatically in recent years. NeuroSci knows about skin irritation and has excellent collaborations with researchers in the field – both scientists and clinicians – and has published a number of high quality research papers in this area.