Skin-care products include both cosmetics and drugs: cosmetic skin-care products can be soaps, shampoos, moisturisers, lipsticks, toothpastes, hair colorants, colour cosmetics, and deodorants, while drugs are distinguished as having a biological effect on living tissue. The word 'cosmetic' comes from a Greek word meaning 'to adorn', and thus such products are intended to affect the surface of the skin, covering and beautifying, usually temporarily. A basic dictionary definition of a cosmetic includes phrases such as 'purporting to improve beauty, especially that of the complexion; correcting defects of the face, etc.', and 'preparations for this purpose'. 'Covering' is indeed used to deal with unsightly birthmarks and port-wine stains, while the term 'cosmetic surgery' is usually used with the implication that a permanent surgical change has been made. In contrast, a drug is an article or product intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease.
For cosmetic claims, the manufacturers substantiate these by tests with human volunteers rather than by rigorous testing on animals followed by clinical trials before they are licensed, which is required for drugs. Cosmetics, or their components, may be tested on animals for toxicity (rather then efficacy), but increasingly this testing is decreasing and advertising claims may include statements that the preparations have indeed not been tested on animals. This may be achieved by using ingredients that have previously and individually been tested for toxicity, and forthcoming European legislation will substantially reduce the amount of animal testing.
A skin-care cosmetic needs to balance the need to provide a specific solution for a skin care need, as well as meeting a variety of other formulation challenges such as being stable for the duration of its shelf-life, being able to resist microbial contamination during use, as well as smelling good and feeling good when the consumer applies it. For consumers, a cosmetic is not just about providing a benefit; it is also about meeting a number of their expectations when they use the product. Cosmetics are designed to give the user a wonderful experience so as to make the users look good, feel good and smell good.
The legal difference between a cosmetic and a drug is basically determined by a product's intended use, although the legal situation of course differs in different countries. The USA's FDA  warns that companies sometimes violate the law by marketing a cosmetic with a drug claim, or by marketing a drug as if it were a cosmetic, without adhering to the requirements for drugs. The situation is confused, however, because some products can meet the definition of both cosmetics and drugs, for example when a product has two intended uses. An example would be of an anti-dandruff shampoo. A shampoo is a cosmetic (its intended use is to cleanse the hair), whereas the anti-dandruff agent is a drug as it is intended to treat a medical condition (dandruff). Other examples might be toothpastes containing fluoride, make-up with sun-protecting claims, and deodorants that are also antiperspirants....