The properties of engineered nanomaterials and nanoparticles such as zinc oxide and titanium dioxide may differ substantially from naturally occurring materials and particles. Nanoparticles have unique physical properties making them ideal for use in various skin care products currently on the market. Nano-preparations are currently under investigation as novel treatments of acne vulgaris, recurrent condyloma accuminata, atopic dermatitis, hyperpigmented skin lesions, and other non-dermatologic diseases. Because of their increased surface area, nanoparticles have increased reactivity and a small size allowing for enhanced mobility through the human body and environment. As their use becomes more prevalent, nanoparticles are being scrutinized for their safety and long-term effects. This review discusses the benefits of nanoparticles in dermatological therapies and skin care products as well as potential disadvantages and possible mechanisms of toxicity.