The main regulatory frameworks governing the cosmetic industry dates back to 1938 in the United States (US) and 40 years later in Europe (EU). Since then, both the US and EU cosmetic legislations have inspired the regulatory framework of a number of countries working toward harmonisation of cosmetics legislation. During the years the requirements for the efficacy of cosmetic products have been implemented to adapt them to the state of the art; however no clear guidelines for efficacy testing on cosmetic products exist. The lack of guidelines and/or shared position on cosmetic testing represents the missing link between the regulatory requirements and the consumer protection from misleading claims in the real life. On the other side a regulatory claimed prerequisite is ineffective if clear and specific testing methodologies are not available to the cosmetic industry. This introduce a discretionary element decreasing the strength of the original regulatory requirement, having an impact on consumer protection from misleading claims, and sometimes decreasing the credibility of the cosmetic product in the marketplace. Initiatives aimed at developing clear, specific for cosmetic products, and effective guidelines should arrive from the academy, industry, and professional associations. This manuscript is aimed to give an overview of the main ethical, technical and regulatory concerns affecting the design of an efficacy study carried out on humans.