Cosmetics
A cosmetic may be defined as any substance that is applied to the body for cleansing, beautifying, promoting attractiveness or altering the appearance. Cosmetics in some form are used by almost everyone. The market for cosmetic sales is vast and far exceeds that of dermatological products. Over recent years, the fields of cosmetology and dermatology have converged so that patients often present having had a reaction to a cosmetic or asking for advice about cosmetic usage. Some cosmetics are now being marketed as ‘cosmeceuticals’ with the claim that they have an ‘active’ ingredient, for example one that can ‘reverse ageing’.
The range of cosmetics and their usage
Cosmetics are normally used to enhance the appearance of the body, to clean it, to impart a pleasing smell or to mask an unpleasant one, or as a fashion accessory. Table 1 shows the range of common types of cosmetics.
| Site | Product |
|---|---|
| Skin | Moisturizer, cleanser, soap, make-up remover, powder, rouge, foundation, toner, perfume, aftershave, bath additive, sunscreen |
| Hair | Shampoo, conditioner, bleach, colourant, permanent waving, straightening, lacquer, gel, hair-removing agents |
| Eyelids | Mascara, eyeshadow, eyeliner, pencil |
| Nails | Nail varnish, false nails |
| Lips | Lipstick, lipgloss, sunscreen |
Constituents of cosmetics
The exact contents of a cosmetic depend on its proposed function. However, commonly used ingredients, some of which will be found in most cosmetics, are detailed in Table 2. Many cosmetics contain perfumes, preservatives and, quite often, a sunblock agent. Cosmetics are often emulsions (e.g. oil-in-water or water-in-oil). Full labelling of contents is required in the European Union, a measure strongly supported by dermatologists. This is a useful development for patients allergic to cosmetic ingredients because they are now able to avoid products that would be problematic. Certain preparations deserve special mention. They are discussed below.
| Ingredient | Action | Examples |
|---|---|---|
| Antioxidant | Prevent degradation | Butylhydroxyanisole, gallates, tocopherol |
| Colorant, dye | Colour | Cochineal, azo compounds, iron dioxides, para-phenylenediamine, titanium dioxide, metal salts, dihydroxyacetone in fake tan |
| Perfume | Smell or for masking smell | Myroxylon pereirae, limonene, geraniol, linalool |
| Preservative | Antimicrobial | Parabens, formaldehyde, iodo-propynyl butyl carbamate, methyl isothiazolin-one/chloro methyl isothiazolin-one, quaternium 15, bromo-nitropropane-diol, imidazolidinyl urea |
| Polyol | Humectant (retains water), emollient | Glycerol, propylene glycol, sorbitol |
| Oil, fat, wax | Emollient, lustre | Vaseline, almond oil, lanolin |
| Sun filter | Absorb or reflect UV | Titanium dioxide, oxybenzone, avobenzone |
| Tensioactive agent | Emulsifier, surfactant, detergent |
