Allergic contact dermatitis caused by cosmetic products is an increasing concern given the continual creation and introduction of new cosmetics to the public. This article presents an overview of how to evaluate a patient for patch testing, including common areas for cosmetic-induced dermatitis, common cosmetic allergens, and proper management.
Key points
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Cosmetics may cause allergic contact dermatitis (ACD) due to common allergenic components that are frequently found in cosmetics.
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The most common sites of reaction are the face and neck. The most common allergens in cosmetics are fragrances and preservatives.
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A thorough patient interview is the key to achieving proper diagnosis and management of cosmetic-induced ACD.
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Patch testing is the gold standard for diagnosing cosmetic-induced ACD, and the addition of a cosmetic series and testing of the patients’ own products can be helpful.
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The mainstay of management is allergen avoidance.
Introduction
The history of cosmetic use is rich and antecedes written history, spanning civilizations and centuries that began with the ancient Egyptians using their natural resources to create a myriad of products such as scented oils, creams, lip stains, and eyeliners. Today, cosmetics are used worldwide and create a steadily increasing multibillion-dollar industry. The term “cosmetic”, according to the US Food and Drug Administration (FDA), means “(1) articles intended to be rubbed, poured, sprinkled, sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance, and (2) articles intended for use as a component of any such articles; except that such term shall not include soap.” With a broad definition that encompasses facial makeup, skincare items, perfumes, hair and nail products, shaving gels or creams, and any personal hygiene product such as toothpaste or deodorant, efforts have been put in place by the creation of the Cosmetic Ingredient Review in 1976 and the FDA to moderate the safety of cosmetic products. However, it is estimated that an adverse reaction to cosmetics occurs approximately once every 13.3 years per person. It is difficult to estimate the frequency of adverse reaction because cosmetics in the general population, and the prevalence is most likely underestimated due to most people do not seek medical advice and simply discontinue use of the product suspected of triggering a reaction.
There are many types of adverse reactions caused by cosmetics. Most adverse reactions are irritant; however, type IV hypersensitivity, contact urticaria, photosensitization, pigmentary disorders, damage of hair and nails, paronychia, acneiform eruptions, folliculitis, and exacerbation of an established dermatosis may also occur. Allergic contact dermatitis (ACD), or a type IV hypersensitivity reaction, is much less common than an irritant dermatitis, and several studies have found the prevalence of ACD to be less than 1% in the general population. Type IV is a delayed-type hypersensitivity reaction that is T-cell mediated, wherein circulating or resident sensitized T cells are activated by the offending allergen to release pro-inflammatory cytokines. Sensitization depends on several factors including product composition, concentration of potential allergenic components, amount of product applied, application site, skin barrier integrity, and frequency and duration of application. Sensitization usually requires repeated exposure and application to damaged skin.
Introduction
The history of cosmetic use is rich and antecedes written history, spanning civilizations and centuries that began with the ancient Egyptians using their natural resources to create a myriad of products such as scented oils, creams, lip stains, and eyeliners. Today, cosmetics are used worldwide and create a steadily increasing multibillion-dollar industry. The term “cosmetic”, according to the US Food and Drug Administration (FDA), means “(1) articles intended to be rubbed, poured, sprinkled, sprayed on, introduced into, or otherwise applied to the human body or any part thereof for cleansing, beautifying, promoting attractiveness, or altering the appearance, and (2) articles intended for use as a component of any such articles; except that such term shall not include soap.” With a broad definition that encompasses facial makeup, skincare items, perfumes, hair and nail products, shaving gels or creams, and any personal hygiene product such as toothpaste or deodorant, efforts have been put in place by the creation of the Cosmetic Ingredient Review in 1976 and the FDA to moderate the safety of cosmetic products. However, it is estimated that an adverse reaction to cosmetics occurs approximately once every 13.3 years per person. It is difficult to estimate the frequency of adverse reaction because cosmetics in the general population, and the prevalence is most likely underestimated due to most people do not seek medical advice and simply discontinue use of the product suspected of triggering a reaction.
There are many types of adverse reactions caused by cosmetics. Most adverse reactions are irritant; however, type IV hypersensitivity, contact urticaria, photosensitization, pigmentary disorders, damage of hair and nails, paronychia, acneiform eruptions, folliculitis, and exacerbation of an established dermatosis may also occur. Allergic contact dermatitis (ACD), or a type IV hypersensitivity reaction, is much less common than an irritant dermatitis, and several studies have found the prevalence of ACD to be less than 1% in the general population. Type IV is a delayed-type hypersensitivity reaction that is T-cell mediated, wherein circulating or resident sensitized T cells are activated by the offending allergen to release pro-inflammatory cytokines. Sensitization depends on several factors including product composition, concentration of potential allergenic components, amount of product applied, application site, skin barrier integrity, and frequency and duration of application. Sensitization usually requires repeated exposure and application to damaged skin.
Epidemiology
Although the prevalence of cosmetic allergy is found to be less than 1% in various studies, it is most likely an inaccurate number due to the tendency of patients to forgo seeking medical attention and discontinue use of the product on their own. A study conducted in the United States of patients with suspected ACD by the North American Contact Dermatitis Group (NACDG) found that after patch testing 10,061 patients over 7 years, 23.8% of female patients and 17.8% of male patients had at least one allergic patch-test reaction associated with a cosmetic source. One review found the pooled prevalence rate of ACD to cosmetics in 7 different studies to be 9.8%. The rate varies with time and geographic location, most influenced by the allergenicity of cosmetic ingredients, a population’s increased use of cosmetics over time, and accessibility of allergens to be used in patch testing. Studies reporting the epidemiology of cosmetic allergy characterize the population most affected with cosmetic sensitivity as female between 20 and 55 years of age.
Evaluation
Cosmetic allergy occurs through direct application of an allergen, or the allergen can be airborne or transferred (usually from the hands and fingernails). Table 1 lists the different ways in which an allergen may come in contact with the skin.
| Type | Definition | Example |
|---|---|---|
| Intentional direct contact | Allergenic ingredient in cosmetic product | Eye cosmetic, deodorant |
| Unintentional direct contact | Allergen-contaminated surface | Towel, pillow, telephone |
| Airborne | Gas, droplet, or particle in the atmosphere | Epoxy resin (occupation-related), cigarette smoke |
| Connubial | Contact with family, friends, colleagues | Perfume or hair dye from spouse |
| Ectopic | Transfer from one site of body to more sensitive area (ie, face, eyelids) | Fingernail varnish |
| Photosensitization | Photoallergens exposed to the sun | Photoallergens in sunscreen |
ACD can be considered in the differential diagnosis according to the site of the reaction on the body and the allergen most likely to come in contact with that region. There are certain areas of presentation where ACD should be considered because of their frequency of cosmetic contact and the possible allergens that such cosmetics contain. These areas are the face, eyelid, neck, hands, scalp, and anogenital region.
Patient evaluation should begin with a thorough medical history and careful investigation of products used by the patient in all settings (house and work), followed by a physical examination. A finding of dermatitis on the following areas should make the clinician suspicious of a cosmetic contact allergy.
Face
The face is the most common site of ACD, and cosmetics are a common cause of this condition. Because of the continually exposed nature of the face, cosmetic allergens come into contact with the face not only through direct application, but also indirectly through the air and through transfer from hands. A pattern of ACD on the face can appear patchy even when a product is applied to the whole face. Facial contact dermatitis is most often thought to be bilateral, but clinicians must still consider this diagnosis even if the whole face is not involved. Of note, dermatitis involving the lateral face, forehead, eyelids, ears, and neck can be observed in patients that experience application of an allergen to the scalp that runs into these adjacent areas, creating a “rinse-off” pattern.
Sometimes an offending agent is not obvious, such as when a patient is sensitized to allergens in cosmetic tools such as the rubber in cosmetic sponges. Less obvious is when a cosmetic allergen has been transferred to a surface otherwise considered innocuous, such as a towel or telephone. The patient history is very important in determining the cause of allergy in such cases.
Eyelids
The eyelids are an extremely sensitive area of the body due to the thinness of skin in this area and ACD is considered the most common dermatologic condition found in association with eyelid dermatitis. The eyelid is a typical site for ectopic contact dermatitis, most commonly caused by allergen from nail varnish or lacquer. Transfer of allergens in hair cosmetics such as p-phenylenediamine (PPD) and ammonium persulfate are widely known to cause a reaction exclusively at the eyelid. Aside from ACD, a differential diagnosis of eyelid dermatitis includes irritant contact dermatitis, protein contact dermatitis, seborrheic dermatitis, atopic eczema, psoriasis, collagen vascular disease, urticaria, rosacea, cutaneous T-cell lymphoma, sarcoidosis, and infections. ACD is presumed to be the most common cause of eyelid dermatitis, occurring in 34% to 74% of patients. Patch testing reveals that fragrance components, preservative agents, emulsifiers, hair-care products, and nail cosmetic ingredients such as acrylates are the main cosmetic allergenic agents causing ACD of the eyelids.
Mascara, eyeliner, eye shadow, fake eyelashes, and metal in eyelash curlers are all considered cosmetic sources of eyelid dermatitis. Shellac is a commonly used cosmetic agent in mascaras that can cause eyelid dermatitis. In a case report from France, 5 out of 5 patients that were patch tested with shellac had positive reactions. Similarly, a study in the United States found 4 patients referred for evaluation of eyelid dermatitis to have used the same mascara, and shellac was the only individual mascara ingredient to which all 4 patients tested positive.
The NACDG published a study in 2007 that identified a list of 26 top contact allergens that could create a “potential screening series for the evaluation of patients with eyelid dermatitis, without other areas of involvement.” Gold tops the list as the most common allergen, accounting for exclusive eyelid dermatitis, and is explained by the release of gold particles in the presence of sweat and abrasive materials, such as titanium dioxide, a common component of facial makeup (an opacifying agent) and sunscreens (blocks ultraviolet light). A patient with metal allergy who wears jewelry may experience this as the gold wears down and the skin is exposed to such substances.
Neck
Similar to the eyelid, the neck is commonly involved in cosmetic-induced ACD due to thinness of the skin and its continual exposure to the environment. ACD affects the neck, either because of products directly applied to the neck or products applied to the face, scalp, and hair that are transferred to the neck, or by contact with metal in jewelry. Nail polish is a well-known cosmetic offender, and a study of ACD from nail varnish determined the face and neck to be the most affected sites. The most common allergen in nail polish was tosylamide formaldehyde resin (TSFR), the ingredient used to create an adhesion between nail polish and the nail. In a separate study, the NACDG found that TSFR was responsible for 4% of positive patch tests. Perfumes are also an obvious source of ACD, as culturally, the neck is the most common place to spray a fragrance. For patients sensitized to fragrances, an “atomizer sign” may develop, wherein repeated application to the neck can cause a focal dermatitis near the prominentia laryngea (Adam’s apple). Such a sign may alert a physician to the cause of neck dermatitis and allow early intervention for proper management.
Hands
Irritant and ACD are the leading causes of hand dermatitis, a common condition that constitutes 20% to 35% of all dermatitis. Aside from irritant and ACD, a differential diagnosis of hand dermatitis includes pompholyx, hyperkeratotic, frictional, nummular, vesicular, and atopic hand dermatitis. ACD of the hands is caused by occupational and nonoccupational allergens, and several studies cite that hairdressing is associated with an increased risk of ACD as compared with the general population. A retrospective cross-sectional analysis of positive patch-test reactions focusing on cosmetic allergens found that hairdressing is the most common occupation associated with allergy to cosmetics, and hair products are the most common source of occupation-related reactions. Hands are the most commonly affected site, with rates of hand dermatitis as high as 93% in patch-tested hairdressers and cosmetologists. Studies report an estimated lifetime risk of hand dermatitis in hairdressers and cosmetologists to be 29.1%, 37.6%, and 44.5%.
Scalp
The scalp can be frequently exposed to cosmetic agents, particularly through the use of hair dyes and shampoos. Because of the thickness of skin on the scalp, it is typically uninvolved in ACD unless the patient is particularly sensitive to PPD, a potent sensitizer commonly used in hair dyes. Such sensitization can lead to edema and crusting of the scalp. The Information Network of Departments of Dermatology, a collaborative effort of multiple dermatology departments in Europe that conducts epidemiologic surveillance of contact allergy, patch tested 1320 patients suspected of ACD of the scalp. They found the most common allergens causing adverse reactions to be hair-coloring agents such as PPD, toluene-2,5-diamine, p-aminophenol, 3-aminophenol, and p-aminoazobenzene. A portion of the patients of this study had their own cosmetic products patch tested. Of those items, medical products, hair tints and bleaches, and hair-cleansing products accounted for approximately two-thirds of positive patch-test reactions, with hair tints and bleaches constituting the largest percentage.
Psoriasis, which commonly presents on the scalp, is one particular condition that can be exacerbated by an ACD. Two separate cases reported patients with stable psoriasis that developed pustular psoriatic lesions of the scalp, triggered by an ACD to zinc pyrithione, a component of shampoos that treats dandruff and scalp psoriasis. Clinicians should be aware of this potential scalp exacerbation due to ACD.
Anogenital
ACD in the anogenital area is uncommon but a cause of significant discomfort. A retrospective analysis of 1238 patch-tested individuals found only 2.4% of patients with genital dermatitis. It occurs through direct contact with anogenital-specific products such as feminine hygiene products, unintentional contact from nonanogenital products transferred to the area, or through oral administration of substances excreted in urine and feces. Common allergens among patients with anogenital involvement are substances found in products used in the anogenital area (fragrances, preservatives, corticosteroids). Following this, they include fragrance, balsam of Peru, and nickel. Spices and flavorings, such as nutmeg, peppermint oil, coriander, curry mix, peppermint oil, and onion powder, are also reported to be associated with anogenital and vulval pruritus and dermatitis.
Due to the natural environment of the genital area, the barrier function is frequently compromised by moisture, friction, and heat, rendering it particularly susceptible to ACD. Reactions can be acute or chronic. Acutely, ACD of the vulva can be severely erythematous, edematous, and ulcerative with possible vesicle formation at the site of contact. Chronic ACD of the vulva occurs via extended exposure to a weak allergen, presenting in a pattern of flares and remission characterized by varying degrees of pruritis. Clinically, the vulva appears erythematous or hyperpigmented, marked by lichenified plaques with variable scale and excoriation.
Common allergens
Preservatives
Formaldehyde-releasing preservatives: Quaternium-15, Imidazolidinyl urea, Diazolidinyl urea, DMDM hydantoin
Formaldehyde is currently used in a variety of products, such as fertilizers, cleaning products, and waterproof glues; however it is rarely used as a cosmetic preservative because it is a frequent sensitizer. In turn, manufacturers use formaldehyde-releasing preservatives, which include Quaternium-15, Imidazolidinyl urea, Diazolidinyl urea, and DMDM hydantoin, substances that still top the list of allergens causing positive patch-test reactions ( Table 2 ). These preservatives are added to numerous skin, hair, and makeup products for their antimicrobial properties. There is legislation in the European Union to limit the amount of these substances in products ; in contrast, there is no regulation in the United States on the concentration or use of any formaldehyde-releasing preservatives. According to data from the FDA, approximately 1 in 5 cosmetic products (19.5%) contains a formaldehyde releaser. Cross-reactivity between formaldehyde and formaldehyde-releasers varies, suggesting that allergy to one formaldehyde-releasing preservative does not necessarily restrict the use of the entire class of formaldehyde-releasing preservatives. It is generally understood that the result of a patch test outweighs the theoretical cross-reactions of formaldehyde-releasing preservatives ( Table 3 ).
| Female | Male |
|---|---|
| Quaternium-15 | Quaternium-15 |
| Myroxylon pereirae (balsam of Peru) | Fragrance mix |
| Fragrance mix | Myroxylon perierae (balsam of Peru) |
| PPD | Diazolidinyl urea |
| Methyldibromoglutaronitrile/phenoxyethanol | Imidazolidinyl urea |
| Formaldehyde | Diazolidinyl urea (not in petrolatum) |
| TSFR | Cocamidopropyl betaine |
| Cocamidopropyl betaine | Formaldehyde |
| Glyceryl thioglycolate | DMDM hydantoin |
| Diazolidinyl urea | p-Phenylenediamine |
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