Contact-allergic reactions to cosmetics may be delayed-type reactions such as allergic and photo-allergic contact dermatitis, and more exceptionally also immediate-type reactions, that is, contact urticaria. Fragrances and preservative agents are the most important contact allergens, but reactions also occur to category-specific products such as hair dyes and other hair-care products, nail cosmetics, sunscreens, as well as to antioxidants, vehicles, emulsifiers, and, in fact, any possible cosmetic ingredient. Patch and prick testing to detect the respective culprits remains the golden standard for diagnosis, although additional tests might be useful as well. Once the specific allergens are identified, the patients should be informed of which products can be safely used in the future.
Nowadays almost everyone is using cosmetics products, which includes cleansing products such as soaps, bath and shower products, shampoos and toothpaste, as well as, for example, deodorants and make-up products. Indeed, they are used to clean, perfume, change the appearance, protect from body odours, and protect and keep the skin, teeth, and mucosal membranes in good condition. They differ from drugs because they lack diagnostic and therapeutic properties.
Allergic reactions to cosmetic products are increasingly observed. The cosmetic allergens involved can reach the skin in several different ways: by direct application, by occasional contact with an allergen-contaminated surface, by airborne contact (e.g., vapours or droplets), by transfer by the hands to more sensitive areas (e.g., the eyelids), by a product used by the partner (or any other person), or be photo-induced, resulting from contact with a photo-allergen and exposure to sunlight, particularly UV-A light. An allergic contact dermatitis may sometimes spread (symmetrically) to other areas of the body not in direct contact with the allergen (id-like spread reaction); this is comparable to a reaction by systemic exposure (in which the allergen may reach the skin through the circulatory system and produce a systemic contact-type dermatitis), the latter being extremely rarely observed with cosmetics. Besides contact dermatitis, being a delayed allergic response, also immediate type reactions, that is, contact urticaria (syndrome), may exceptionally occur.
Physical examination and history taking frequently suggest the etiological factor(s), but patch (or epicutaneous) testing is used for diagnosing, with at least two readings of the test results, that is, at day 2 and 4/5 following their application. Allergen identification for a patient with a possible contact allergy to cosmetics is performed by means of patch testing with the baseline (standard) series, specific cosmetic-test series, the products used, along with their ingredients. With regard to the diagnosis of photoallergic contact dermatitis, photo-patch tests need to be performed: the allergens are tested in duplicate on the back and irradiated with U.V. light (most often UV-A 5 J/cm−2). Readings should be recorded immediately and 2 days, as well as at 3 or 4 days postirradiation.
Sometimes open or semiopen (or semiocclusive) tests [
With ROAT, a very small amount or about 0.1 mL of test material is applied twice daily to the flexor aspect of the forearm near the cubital fossa, to an area approximately 5 × 5 cm. The results are read after 1 week, but sometimes ROAT need to be performed up to 21 days, especially with low-concentrated allergens, to reveal an allergic reaction.
Once an allergen has been identified, it is the dermatologist's task to provide specific advice about the products that can be safely used, since subjects sensitive to specific ingredients must avoid products containing them. Although cosmetic labelling exists, providing the allergic patient with a limited list of cosmetics that can be used is, in our experience, most practical and effective [
In cosmetics, fragrances and preservative agents are the most important culprits, but reactions also occur to category-specific products such as hair dyes and other hair-care products, nail cosmetics, sunscreens, as well as to antioxidants, vehicles, emulsifiers, and, in fact, any possible cosmetic ingredient [
They are frequent culprits in cosmetic allergies. Sensitization is most often induced by highly perfumed products, such as toilet waters, after-shave lotions, and deodorants, but fragrance-containing skin-care products may also cause reactions [
The literature confirms that the fragrance mix, which contains 8 perfume components (amyl cinnamal, cinnamal, cinnamyl alcohol, hydroxycitronellal, eugenol, isoeugenol, geraniol, and Evernia prunastri (oakmoss) extract, all diluted 1% in petrolatum and emulsified with sorbitan sesquioleate) and which is tested routinely in the baseline series, remains the best screening agent for contact allergy to perfumes because it can detect some 70% to 80% of all perfume allergies [
Multiple positive patch-test reactions are frequently associated with fragrance allergy and often indicate the presence of common or cross-reacting ingredients in natural products (e.g., also to plants of the
Fragrance components may be allergenic by themselves, but may also contain sensitizing oxidation products, as is the case with, for example, limonene [
They are very imporant cosmetic allergens in water-based products such as cleansers, skin-care products and make-up [
Particularly methyldibromoglutaronitrile—that was used in a mixture with phenoxy-ethanol, better known as Euxyl K400—became such an important cosmetic allergen [
The incidence of positive reactions to formaldehyde and its releasers is slightly increasing again (data from the European Environmental Contact Dermatitis Research Group 2008, not published). Meanwhile, parabens are rare causes of cosmetic dermatitis and when allergy does occur, the sensitization source is most often a topical pharmaceutical product. This is often the case also for, for example, mefenesin, a rubefacient in topical pharmaceutical products, which cross-reacts with chlorphenesin, used as a preservative agent in cosmetics (data on file) and thus a potential sensitizing agent [
They are only a minor group of cosmetic allergens. Examples are propyl gallate, octyl gallate [
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Because of media attention being given to the carcinogenic and accelerated skin-aging effects of sunlight,
The contribution of sunscreens to cosmetic allergy has been considered to be relatively small despite the increase in their use; however, the low rate of allergic reactions observed may well be because a contact allergy or a photo-allergy to sunscreen products is often not recognized, since a differential diagnosis with a primary sun intolerance is not always obvious. Furthermore, the patch-test concentrations generally used might be too low, in part because of the risk of irritancy. Last but not least, photo-patchtesting is not at all routinely performed in a dermatologic practice!
They are common ingredients to topical pharmaceutical and cosmetic products. The classical contact-allergens reported were rare cosmetic allergens, such as wool alcohols, fatty alcohols (e.g., cetyl alcohol), and propylene glycol [
Other possible allergens include ethylhexylglycerin (syn.: octoxyglycerin), a skin conditioning agent [
Plant extracts and herbal remedies have become very popular in recent years and may give rise to (sometimes severe) contact dermatitis problems [
Protein-derived ingredients, in particular, are often used in skin-care products, especially in those for treating dry skin in atopic subjects (often children). Allergic contact dermatitis (sometimes located mainly on the eyelids) from, for example, oat meal (
Contact urticaria appears immediately (mostly within 5 to 20 minutes, exceptionally later) upon contact with the causal agent. The skin reaction is clinically characterized by redness and oedema (sometimes urticarial papules), and may, when immunologically mediated, be accompanied by extracutaneous symptoms such as conjunctivitis, respiratory problems, dizziness, and even anaphylaxis. This is referred to as the “contact urticaria syndrome” in which 4 stadia can be recognized.
Cutaneous symptoms: Stadium 1: localised urticaria, Stadium 2: generalised urticaria, extracutaneous symptoms, Stadium 3: bronchial asthma, rhinoconjunctivitis, otolaryngeal, gastrointestinal symptoms, Stadium 4: anaphylaxis.
The diagnosis of contact urticaria consists of a careful history, inspection of the clinical symptoms, and the performance of immediate tests: the suspected materials are tested as such (open), but mostly with prick testing. Readings are performed immediately and up to 1 hour. Also a provocation or usage test can be performed. However, if the anamnesis or the clinical symptoms observed point to a severe extracutaneous reaction, attention is to be paid not to elicit a severe reaction on testing, which should be performed in a hospital environment only. In case of an immunologic-mediated urticaria, specific IgE-antibodies can be searched for. Indeed, there also exists nonimmunologic contact urticaria (NICU), for example, caused by chemicals, such as cinnamal (a fragrance component), and sorbic and benzoic acids (preservatives).
Cosmetic examples of substances to which also severe reactions have been reported are permanent hair dyes containing PPD [
Fragrance components and preservatives are the most frequent cosmetic contact allergens; however, all ingredients must be considered as potential culprits and patchtested. Besides allergic contact dermatitis, also immediate-type reactions may occur, for which prick tests are the golden standard for diagnosis. Once the specific allergens are identified, the patient should be informed on which products can be safely used in the future. Indeed, the so-called “hypoallergenic” products are not necessarily less sensitizing [
This work received support from several companies to the Dermatology Department to set up databases with information to patients and dermatologists.