Author: Vanessa Ngan, Staff Writer, 2012.
A cosmetic is defined as a topically applied product that is used to beautify, cleanse or protect the hair, skin, teeth or complexion.
In essence, a cosmetic should not contain any active drug ingredient that may affect the structure or function of the skin. The division of cosmetics and drugs is not always clear as there are many products available that have two intended uses, for example, an antidandruff shampoo is a cosmetic because it is intended to cleanse the hair but it also contains a drug to treat the scalp and dandruff. Such products must comply with the requirements for both cosmetics and drugs.
Cosmetics can be broadly divided into the following groups.
Countries around the world have in place regulatory standards that ensure these products are safe for the workers handling them, the environment, and for use by consumers.
It is estimated that on average women are using at least seven types of cosmetic each day and reactions to these products are quite common. Although the prevalence of cosmetic allergy in the general population is unknown, several studies suggest that up to 10% of the population will have some type of reaction to a cosmetic over the course of a lifetime. This figure may be much higher as many mild reactions occurring at home are self-diagnosed and often self-treated.
Cosmetics can produce a range of adverse reactions.
Some people may develop more than one type of reaction. For example, an atopic individual may be prone to irritant contact dermatitis, which in turn increases their likelihood of allergic contact dermatitis, as their skin barrier function is weakened and sensitised to the allergen.
It is possible for a cosmetic allergy to develop even after years of using a cosmetic without previous problems.
The range of cosmetics is vast so the pool of allergens is infinitely huge. The groups of allergens that appear to most frequently cause cosmetic allergy are fragrances, preservatives, and paraphenylenediamine (PPD) found in hair dyes.
Other allergens used in cosmetics that can cause cosmetics allergy include:
Cosmetic allergy is diagnosed by performing patch tests. A diagnosis may involve testing against a number of different chemicals due to the many potential allergens in cosmetics, as well as the person's own cosmetics applied as is. See individual contact allergens for patch testing recommendations.
An open application test may also be recommended.
Contact dermatitis should clear rapidly once the cosmetic allergen is removed. Over-the-counter creams and ointments containing mild topical steroids, such as hydrocortisone cream, may be used to help control itching, swelling, and redness. A prescription steroid cream may be required for severe reactions, as well as an antibiotic for a secondary bacterial infection. Bland emollients such as cetomacrogol cream can be used to soothe and relieve dryness.
The best way to prevent contact allergic dermatitis to cosmetics is by avoiding all products that contain the allergen.
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