Atopic dermatitis (AD) is a chronic disease that affects the skin, and that is characterized by highly itchy inflammation, frequent eczematous lesions, and a fluctuating course. The current treatment consists of a multi-stage approach that aims to establish persistent disease control towards the improvement of the quality of life of the patients. Topical therapy is the basis of AD treatment, however, due to the difficulty of crossing the skin barrier, topical application of drugs remains a challenge. In fact, in addition to the low skin bioavailability, and limited accessibility to deeper skin of the drugs - due to difficulty in penetrating the epidermis - implemented drugs in the clinical are associated with serious adverse effects, which are responsible for safety and efficacy limitations, leading to a reduction in patients' compliance. Nanotechnology arises as an emerging approach for the treatment of AD, allowing for controlled release, targeted delivery, improved penetration, and bioavailability of drugs assets, resulting in marked improved therapeutic efficacy and reduction of adverse effects. Although its promising outputs, additional studies are needed to recognize the toxicological characteristics, cost-benefit, and long-term safety of nanocarriers applied to this end. Advanced drug delivery systems, particularly nanoemulsions, liposomes, ethosomes, transfersomes, solid lipid nanoparticles, nanostructured lipid carriers, nanocrystals, polymeric nanoparticles, and polymeric micelles have been used, and are thoroughly addressed in this review as promising nanoformulations towards the topical treatment of AD.

Nanomaterials use in cosmetics is markedly enhancing, so their exposure and toxicity are important parameters to consider for their risk assessment. This review article provides an overview of the active cosmetic ingredients used for cosmetic application, including dermal cosmetics and also hair dye cosmetics, as well as their safety assessment, enriched with a compilation of the safety assessment tests available to evaluate the different types of toxicity. In fact, despite the increase in research and the number of papers published in the field of nanotechnology, the related safety assessment is still insufficient. To elucidate the possible effects that nanosized particles can have on living systems, more studies reproducing similar conditions to what happens in vivo should be conducted, particularly considering the complex interactions of the biological systems and active cosmetic ingredients to achieve newer, safer, and more efficient nanomaterials. Toward this end, ecological issues and the toxicological pattern should also be a study target.