Erythematous dermatitis is a very common cutaneous alteration in cosmetics and dermatology. It may be due to various causes that lead to acute, subacute or chronic dermal vasodilation. Among the most frequent cosmetic causes we can include climatic and environmental factors such as sunlight, abundant use of water or other irritants. Irritative dermatitis is characterized by the appearance of erythema of varying degrees that can be associated with burning and itching sensation. The skin tends to dry out due to the loss of water in the stratum corneum and to the increased cell turnover which modifies the process of keratinocyte differentiation and, consequently, the lipid content of the skin.

For tackling this problem, it’s necessary to use topical products containing moisturizing principles, able to supply the lipids normally present in the epidermis so as to restore the skin hydrolipidic film and soothing principles with a vasoconstrictive action; the effectiveness of these products is assessed on the basis of the ability to reduce the degree of erythema and its symptoms.

In the medical literature there are numerous works that demonstrated the soothing action of numerous cosmetic principles (Katsarou 2000, Atrux-Tallau 2010, Szél 2015). The efficacy can be evaluated in different ways (Colipa 1997) but the test on human volunteers is the preferred one. With the introduction of non-invasive instrumental measurement techniques that apply to humans, the properties of dermatological cosmetic products can be evaluated objectively, allowing the detection of little changes in morphology and skin function otherwise not detectable by sensory means.

These efficacy assessments are essential to provide evidence-based support for manufacturers, for dermo-cosmetic operators who need advice and for the consumer.