Cosmetics can be considered as primary elements essential for skin protection, and are part of our daily routines. From cleansing, to make-up and hydration. It is this increase in availability and consumption that has led dermatologists in recent years to pay more attention to the possible side effects as a result of their use. Dermocosmetology studies these compounds. Essentially it is a formula-based discipline, i.e. relative to the combination of ingredients and their skin functions. But it is also dedicated to the study and treatment of the allergenic and sensitising phenomena that these products can cause. The key concept is to combine a number of known substances, using specifically defined proportions, to obtain a topical functional product, stable for multiple use, as harmless as possible and extremely pleasant on the skin.

Cosmetology divides the skin into three types: normal, oily and dry. This actually serves to divide skins into merchandise rather than dermatological based skin types, as we often read on the product claims and instructions for use. It does, however, facilitate research on the formulations of various cosmetic products that correspond to that subdivision.

Key substances in the creation of cosmetics: :

Vegetable, mineral and synthetic oils, Pigments, Emulsifiers, Dyes, Surfactants, Thickeners, Humectants, Fragrances; Sequestering agents; Waxes; Anti-oxidants; Plant extracts, Antibacterial, Sunscreens.

Most common physical forms:

Aerosols, Powders, Gel, Sticks; Emulsions, Sprays, Lotions, Fluid suspensions, Pastes, Foams, Solutions, Solids;

Substances that may cause hypersensitivity to cosmetic products

  • Paraphenylendiamine (PPD) is present in hair dyes.
  • Lanolin wax alcohols of natural origin (sheep sebum) used as softeners and emulsifiers. Present in creams and ointments.
  • Glyceryl thioglycolate used in hair perm solutions.
  • Nickel pollutant resulting from the processing of cosmetics.
  • Cinnamates present in the solar chemical filters for UVA protection, and also in shampoos, creams, and shaving products.
  • Parabens, the preservatives most commonly used in cosmetics and medicines. These rarely trigger allergies on healthy skin.
  • Fragrances are added to cosmetic products to make them more appealing. There are over 5,000 fragrances used, the most controversial being Lyral which is of synthetic origin.
  • Quaternium-15 (Dowcill 200) is a preservative that releases formaldehyde found in many cosmetics such as eye make-up, foundation, shampoo, moisturising lotions, sunscreens, body powders and skin cleansers.
  • Euxyl, a broad-spectrum anti-infective agent which consists of Diazolidinyl Urea, Sodium Benzoate and Potassium Sorbate.
  • Kathon CG is a mixture of isothiazolinones which are used as a preservative and found in many cosmetics, cleansers and hair products.