20 Years of standard patch testing in an eczema population with focus on patients with multiple contact allergies

Decrease of contact allergy to hydroxyisohexyl 3-cyclohexene carboxaldehyde in Europe prior to its ban and diagnostic value

BACKGROUND

Hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) has been the most reported fragrance chemical for two decades and will be prohibited in cosmetic products from August 2021.

OBJECTIVES

To describe the time trend of HICC contact allergy in European patients with dermatitis in 2009 to 2019, and the added value of testing HICC separately in the baseline series.

METHODS

Data were reviewed for 124 472 patients with dermatitis who were patch tested with HICC 5% pet. in the baseline series in the European Surveillance System on Contact Allergy (ESSCA) network (2009 to 2018) and at the Herlev-Gentofte Hospital Department of Dermatology and Allergy (2009 to 2019).

RESULTS

Contact allergy to HICC was found in 1.98% of 9865 patients in Gentofte and 1.62% of 114 607 patients in the ESSCA network. Overall, the prevalence decreased annually, with 0.156 percentage points (P = .001) in Gentofte and 0.051 percentage points (P = .0002) in ESSCA. The frequency of missed contact allergy to HICC when testing only with fragrance mix II (FMII) was 0.17% (17/9865) and 0.35% (405/114607) of the whole test population in the Gentofte and ESSCA populations, respectively.

CONCLUSIONS

This is the first study to demonstrate a significant decline in HICC allergy in European patients with dermatitis, most likely attributed to the upcoming European ban.

Ubiquity, Hazardous Effects, and Risk Assessment of Fragrances in Consumer Products

Purpose of review

The main aims of fragrances are to create pleasing scents or to mask unpleasant odors. We hereby review their main exposure sources, presumed benefits, and unwanted effects, with special attention to allergic contact dermatitis (prevalence, regulatory environment, risk assessment methodology, and preventive measures).

Recent findings

Fragrances elicit positive emotions and presumably have therapeutic benefits related to stress reduction and memory enhancement. However, they also cause detrimental health or environmental effects including contact dermatitis (irritant and/or allergic), non-eczematous contact reactions, photosensitivity, photo-allergy, and immediate contact reactions, which can negatively impact the quality of life. Fragrances are the most frequent chemicals causing contact dermatitis. Their main sources are cosmetics, household products, industrial substances, food flavorings, oral hygiene products, and topical medications. It is difficult for sensitized patients to avoid contact with fragrances, due to their ubiquity and because manufacturers are not willing to volunteer information regarding fragrance ingredients.

Summary

The treatment of contact dermatitis relies on allergens avoidance which does not “cure” the disease (sensitization persists for life) but prevents disabling illness. The patient should understand that avoiding perfume means to avoid all scented goods and not just perfumes.

Labeling fragrances is key in primary prevention (by giving the healthy individual the chance to make an informed choice to avoid risky substances), diagnosis (by helping the practitioner to plan and interpret patch tests), secondary prevention, and prognosis (by allowing the sensitized patient to follow the avoidance instructions). However, only 26 fragrances are mandatory to be declared in cosmetics. The vague labeling of other fragrance ingredients as “perfume” or “fragrance” hampers the diagnostic and preventive approaches. Therefore, in our opinion, declaration should be mandatory for all fragrance ingredients as well as straightforward so most consumers can understand it. Moreover, legislation should be improved to prevent inappropriately high exposures by forbidding stronger allergens, restricting maximum concentrations in the finished product or fields of application, delivering information regarding the risks to the general public, and controlling the compliance of manufacturers with the regulations. Besides, manufacturers should share information regarding the composition in the final products and provide physicians with samples of all fragrance chemicals whenever needed for patch test investigations.

Formaldehyde as an alternative to antibiotics for treatment of refractory impetigo and other infectious skin diseases

Introduction: Antibiotic-resistant strains of bacteria are an increasing problem in hospitals and in the community. This has resulted in bacterial infections such as impetigo becoming difficult to treat. Alternative treatment options are needed. Areas covered: In this paper, a past study that assessed the health burden of scabies in North Queensland is described and from it, the potential for formaldehyde as an alternative antimicrobial treatment is discussed. In doing so, antibiotic resistance, impetigo, permethrin, and formaldehyde are introduced and the current understanding and limitations of the effects of formaldehyde on humans are outlined. The limited cases of formaldehyde resistance in bacteria are also discussed. Expert opinion: Formaldehyde is currently used as a preservative in cosmetics and medicinal creams due to its antibacterial activity. It, therefore, has the potential to be used as an alternative antibacterial treatment for infections with antibiotic-resistant bacteria. The harmful side effects of airborne formaldehyde and exposure in allergic individuals have been extensively studied. Significantly less research has been conducted on formaldehyde skin contact in healthy individuals. If formaldehyde is safe for topical use in humans, it has the potential to assist with combating antibiotic resistance.

Analysis of Epicutaneous Patch Test Results in Patients with Contact Dermatitis

Background:

Allergic contact dermatitis (ACD) is a delayed type of hypersensitivity from contact with a specific allergen to which the patients has developed a specific sensitivity. The aim of the study was to evaluate the results of epicutaneous patch testing with standard series of contact allergen in patients suspected to have ACD.

Methods:

355 cases of ACD were included in the study. Test substances were applied on the upper part of the patient’s back, on clinically uninvolved and untreated skin. All patients were free from therapy with oral antihistamines, steroids and immunosuppressants. The patch test was removed and reaction were evaluated after 48 h and 72 h. Grading of negative (-) to positive (+ to ++++) patch test was done according to the International Contact Dermatitis Research Group. Statistical data analysis was performed by using χ²–test.

Results:

Of the 355 cases, 146 patients were male (41.1%) and 209 were female (58.9%). The youngest patients in the study was 16 years of age and the oldest was 67 years of age. The commonest age group affected was 41-50 years. Hands were the most common site of involvement. The occupational character of skin lesions was find in 75 (21.1%). The most common positive reactions were recorded to nickel sulphate 99 (27.8%), cobalt chloride 46 (12.9%), thimerosal 31 (8.7%), colophony 23 (6.5%), carba mix 21 (5.9%), potassium dichromate 20 (5.6%), acid chromici 19 (5.3%), fragrance mix 18 (5%), balsam of Peru 13 (3.7%), formaldehyde 9 (2.5%), and other allergens 26 (7.3%). Females were significantly more likely to show a positive response to two or more allergens (p<0.05). There was no statistically significant impact of age, occupation and duration of disease on results of patch testing (p>0.05).

Conclusions:

Our results indicate that nickel sulphate, cobalt chloride and thimerosal are the most common allergens responsible for induction of ACD. These findings are crucial in the treatment, long term management, an education of patients with ACD.

Sensitization to, and allergic contact dermatitis caused by, colophonium in north-eastern Italy in 1996 to 2016 with a focus on occupational exposures

BACKGROUND

Colophonium is a natural substance derived from Pineaceae trees. It is used in a wide range of consumer and occupational products because of its tackiness, and is a known sensitizer.

OBJECTIVES

To analyse the temporal trend of contact allergy to colophonium in north-eastern Italy, and to evaluate the associations with occupations in our geographical area.

METHODOLOGY

From 1996 to 2016, 27 381 patients with suspected allergic contact dermatitis were patch tested in north-eastern Italy. Individual characteristics were documented by use of a standardized questionnaire in 6 departments of dermatology or occupational medicine.

RESULTS

The overall prevalence of colophonium sensitization was 1.67%; the prevalence was significantly higher in women (1.75%) than in men (1.49%). No significant differences among departments were observed. We found significant associations between colophonium sensitization and being a student (odds ratio [OR] 4.64; 95% confidence interval [CI]: 1.04-20.6), being a farmer or fishermen (OR 3.63; 95%CI: 1.21-10.84), being a housekeeper (OR 2.02; 95%CI: 1.08-3.77), and being retired (OR 2.06; 95%CI: 1.08-3.92).

CONCLUSION

Our study showed that contact allergy to colophonium is still relevant in north-eastern Italy. The frequency of sensitization has dropped significantly over a period of 10 years, but students and farmers/fishermen still have sensitization prevalences above 3.5%. Our results are in line with European data.

Comparing reliabilities of strip and conventional patch testing

BACKGROUND

The standardized protocol for performing the strip patch test has proven to be valid, but evidence on its reliability is still missing.

OBJECTIVE

To estimate the parallel-test reliability of the strip patch test as compared with the conventional patch test.

METHODS

In this multicentre, prospective, randomized, investigator-blinded reliability study, 132 subjects were enrolled. Simultaneous duplicate strip and conventional patch tests were performed with the Finn Chambers^® on Scanpor^® tape test system and the patch test preparations nickel sulfate 5% pet., potassium dichromate 0.5% pet., and lanolin alcohol 30% pet. Reliability was estimated by the use of Cohen's kappa coefficient.

RESULTS

Parallel-test reliability values of the three standard patch test preparations turned out to be acceptable, with slight advantages for the strip patch test. The differences in reliability were 9% (95%CI: -8% to 26%) for nickel sulfate and 23% (95%CI: -16% to 63%) for potassium dichromate, both favouring the strip patch test.

CONCLUSIONS

The standardized strip patch test method for the detection of allergic contact sensitization in patients with suspected allergic contact dermatitis is reliable. Its application in routine clinical practice can be recommended, especially if the conventional patch test result is presumably false negative.

Cobalt release and complications resulting from the use of dental prostheses

BACKGROUND

Cobalt release from dental prostheses has been shown to elicit allergic reactions in cobalt-allergic patients. It is therefore important to investigate whether these prostheses are possible sources of sensitization.

OBJECTIVES

To assess (i) cobalt release from dental prostheses and (ii) allergic reactions to components of dental prostheses, and (iii) to investigate the oral mucosa for inflammation 1-5 years after insertion of the prostheses.

METHOD

Clinical oral examination was conducted in 66 patients with 84 dental prostheses. Cobalt release from 84 functional (used) and 32 non-functional (new) prostheses was investigated with the cobalt spot test. Contact allergy was assessed by patch testing. Smear tests for Candida spp. were performed in patients showing signs of inflammation of the oral mucosa. The prostheses were assessed for biological and technical complications.

RESULTS

None of the functional prostheses released cobalt, whereas this was observed in 24 of 32 non-functional prostheses. None of the patients had contact allergy to cobalt. Of the 66 patients, 11 showed signs of inflammation of the oral mucosa, 2 had oral candidiasis, 16 had ill-fitting prostheses, and all had insufficient oral hygiene.

CONCLUSIONS

Dental prostheses released cobalt during the fabrication stages, but not 1-5 years after insertion. No allergic reactions were observed. Signs of inflammation were related to candidiasis, insufficient oral hygiene, and ill-fitting prostheses.

Can contact allergy to p-phenylenediamine explain the high rates of terpene hydroperoxide allergy? - An epidemiological study based on consecutive patch test results

BACKGROUND

Contact allergy to linalool hydroperoxides (Lin-OOHs) and limonene hydroperoxides (Lim-OOHs) is common. Similarly to what occurs with the terpene hydroperoxides, reactive intermediates formed from p-phenylenediamine (PPD) can cause oxidative modifications of tryptophan residues on proteins in mechanistic studies.

OBJECTIVES

To test the hypothesis that patients sensitized to PPD are at increased risk of concomitant reactivity to either of the terpene hydroperoxides, owing to a 'common pathway' of skin protein oxidation.

METHODS

A database study of consecutively patch tested eczema patients (n = 3843) from 2012 to 2015, tested concomitantly with PPD, Lim-OOHs and Lin-OOHs, was performed. Associations were examined by level of concordance and odds ratios (ORs) adjusted for age, sex, and contact allergy to fragrance mix I and fragrance mix II.

RESULTS

Concomitant reactions to PPD were seen in 2.2% of Lim-OOH-positive patients and in 4.9% of Lin-OOH-positive patients. Neither proportion was higher than expected by chance. No association existed between PPD and Lim-OOH patch test reactivity. In a multiple logistic regression analysis, PPD allergy was associated with an insignificantly increased risk (OR 2.11, 95%CI:0.92-4.80) of a positive patch test reaction to Lin-OOHs.

CONCLUSIONS

PPD sensitization cannot explain the high rates of sensitization to Lin-OOHs and/or Lim-OOHs. Contact allergy to oxidized linalool is more strongly associated with fragrance allergy than with PPD allergy.

Contact dermatitis: a practice parameter-update 2015

This parameter was developed by the Joint Task Force on Practice Parameters, which represents the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Contact Dermatitis: A Practice Parameter-Update 2015." This is a complete and comprehensive document at the current time. The medical environment is changing and not all recommendations will be appropriate or applicable to all patients. Because this document incorporated the efforts of many participants, no single individual, including members serving on the Joint Task Force, are authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information or interpretation of this practice parameter by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by the pharmaceutical industry in drug development or promotion. Previously published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available at http://www.JCAAI.org or http://www.allergyparameters.org.

Sorbitan sesquioleate; a rare cause of contact allergy in consecutively patch tested dermatitis patients

BACKGROUND

Sorbitan sesquioleate (SSO) has been added to fragrance mix I (FM I) as an emulsifier since the 1990s. Being a contact allergen itself, SSO has the potential to cause false-positive reactions to FM I. Recent results obtained with selected FM I-positive patients have shown that 5% have concomitant positive reactions to SSO.

OBJECTIVES

To investigate the 5-year prevalence of contact allergy to SSO and evaluate the importance of SSO allergy when patch test results for FM I are interpreted.

METHODS

This was a retrospective database study of consecutively patch tested eczema patients (n = 4,637) from 2010 to 2014. All patients were tested with our baseline series including FM I and SSO 20% in pet.

RESULTS

Sensitization to SSO was identified in 9 (0.2%) patients. The proportion of FM I-positive patients with concomitant positive reactions to SSO was 1.4%.

CONCLUSIONS

SSO is a rare cause of contact allergy, with a 5-year prevalence of 0.2% in consecutively tested patients. Contact allergy to the emulsifier does not play a major role when the overall frequency of contact allergy to FM I is evaluated. However, to correctly diagnose individual patients, concomitant patch testing with FM I and SSO is encouraged.

Polysensitization in Recurrent Lip Dermatitis

Background:

In allergic contact dermatitis (ACD), polysensitization consists of positive patch test reactions to three or more unrelated allergens.

Objective:

The purpose of this case report is to document a 27-year-old female with recurrent lip dermatitis, polysensitization, and reactions to a number of clinically relevant exposures.

Methods:

Patch testing results revealed positive reactions to tixocortol-21-pivalate (3+), lanolin (3+), neomycin (3+), nickel (1+), hydroxyethyl methylacrylate (3+), bacitracin (3+), and abitol (3+).

Results:

The patient had seven positive reactions, meeting the criteria for polysensitization. Of known clinical relevance, the patient had applied lanolin-containing lip balms and hydrocortisone- and bacitracin-containing products to the lips, all of which she was strongly reactive to on patch testing.

Conclusion:

Polysensitization occurs when three or more unrelated allergens are positive on patch testing. This case highlights the importance of considering polysensitization in ACD as numerous allergens that were positive on patch testing were clinically relevant.

Risk factors of polysensitization to contact allergens

BACKGROUND

'Polysensitization' (PS) is usually defined as contact sensitization to three or more unrelated haptens of the baseline patch test series. Despite PS being an important clinical phenotype indicating increased susceptibility to contact allergy, statistical approaches to analyse PS have hitherto been preliminary.

OBJECTIVES

To apply an appropriate regression model for count data, namely, negative binomial hurdle regression, to a large set of clinical patch test data with the aim of estimating PS risk in more detail than previously achieved.

METHODS

The detailed information provided by the hurdle model includes a separate estimation of an 'increment factor' quantifying the likelihood of further positive reactions, i.e. PS. Clinical data of 126 878 patients patch tested by departments comprising the IVDK (Information Network of Departments of Dermatology) network (www.ivdk.org) between 1995 and 2010 were included.

RESULTS

Regarding anatomical sites as exposure (surrogate), the axillae and the feet were found to be strong PS risk factors. Moreover, age was a strong PS risk factor, and less so, female sex. In comparison, atopic eczema and occupational dermatitis were less important risk factors. Single allergens contributed to PS to a varying extent.

CONCLUSIONS

The data presented point to some, very likely exposure-related, risk factors which need to be considered in future PS research, e.g. addressing the genetic basis for PS.

Association between cancer and contact allergy: a linkage study

Background Contact allergy is a prevalent disorder. It is estimated that about 20% of the general population are allergic to one or more of the chemicals that constitute the European baseline patch test panel. While many studies have investigated associations between type I allergic disorders and cancer, few have looked into the association between cancer and contact allergy, a type IV allergy. By linking two clinical databases, the authors investigate the possible association between contact allergy and cancer. Methods Record linkage of two different registers was performed: (1) a tertiary hospital register of dermatitis patients patch tested for contact allergy and (2) a nationwide cancer register (the Danish Cancer Register). After linking the two registers, only cancer subtypes with 40 or more patients registered were included in the analysis. The final associations were evaluated by logistic regression analysis. Results An inverse association between contact allergy and non-melanoma skin- and breast cancer, respectively, was identified in both sexes, and an inverse trend for brain cancer was found in women with contact allergy. Additionally, a positive association between contact allergy and bladder cancer was found. Conclusion The inverse associations support the immunosurveillance hypothesis (ie, individuals with an allergy are less likely to get cancer due to a triggered immune system), while the positive association with bladder cancer could be due to accumulations of chemical metabolites in the bladder. The authors' findings add to the limited knowledge about contact allergy and the risk of cancer.

Genetic factors in contact allergy--review and future goals

The genetics of contact allergy are still only partly understood, despite decades of research; this might be a consequence of inadequately defined phenotypes used in the past. A recommendation is to study an extreme phenotype, namely, polysensitization (sensitization to three or more unrelated allergens). Another approach to unravel the genetics of contact allergy is the study of candidate genes. In this review, we summarize studies on the associations between genetic variation (e.g. single-nucleotide polymorphisms) in certain candidate genes and contact allergy. Polymorphisms and mutations affecting the following proteins were studied: (i) filaggrin; (ii) N-acetyltransferase (NAT) 1 and 2; (iii) glutathione-S-transferase (GST) M and T; (iv) manganese superoxide dismutase; (v) angiotensin-converting enzyme (ACE); (vi) tumour necrosis factor (TNF); and (vii) interleukin-16 (IL-16). The polymorphisms of NAT1, NAT2, GSTM, GSTT, ACE, TNF and IL-16 were shown to be associated with an increased risk of contact allergy. In one of our studies, the increased risk conferred by the TNF and IL-16 polymorphisms was confined to polysensitized individuals. Other relevant candidate genes may be identified by studying diseases related to contact allergy in terms of clinical symptoms, a more general pathology (inflammation), and possibly an overlapping genetic background, such as irritant contact dermatitis.

Contact dermatitis in older adults: a review of the literature

Contact dermatitis is a significant health problem affecting the elderly. Impaired epidermal barrier function and delayed cutaneous recovery after insult enhances susceptibility to both irritants and allergens. Exposure to more numerous potential sensitizers and for greater durations influences the rate of allergic contact dermatitis in this population. Medical co-morbidities, including stasis dermatitis and venous ulcerations, further exacerbate this clinical picture. However, while these factors tend to increase the degree of sensitization in the elderly, waning immunity can actually decrease such a propensity. This interplay of both intrinsic and extrinsic factors makes a generalization on trends for contact dermatitis in older adults challenging. The literature has varying reports on the overall incidence of allergic contact dermatitis with advancing age. Nevertheless, it does clearly show that sensitivity to topical medicaments increases with age. Irritant contact dermatitis studies are more consistent, with less reactivity (to irritants) in older compared with younger skin. Diagnosis of both irritant and allergic contact dermatitis is based on a thorough history, complete skin examination, and comprehensive patch testing. The mainstay of therapy is avoidance of the offending chemical substances and the use of topical along with systemic therapies, depending on the severity of the condition.

Characterization of the polysensitized patient: a matched case-control study

BACKGROUND

Polysensitization ( >or= 3 contact allergies) may be regarded as a special entity in patients with contact allergies. However, this group of polysensitized patients is poorly characterized. Filaggrin mutations are associated with atopic eczema and lead to impaired skin barrier which may predispose to contact allergy. Therefore, it is of interest to consider atopic eczema and contact allergies, especially in patients with multiple allergies.

OBJECTIVE

To characterize polysensitized patients regarding occurrence, duration and course of dermatitis, and examine potential risk factors for polysensitization, including atopic eczema.

METHODS

A questionnaire case-control study of 562 polysensitized and 1124 single/double-sensitized individuals was performed.

RESULTS

The results show that 45% of polysensitized and 31% of single/double-sensitized patients had or had had atopic eczema, and atopic eczema was identified as a risk factor for polysensitization. Patients with leg ulcer constituted only a minor part of the polysensitized group and leg ulcers were not identified as a risk factor for polysensitization in this study. The influence of contact allergies on duration and course of disease diverged between the group of patients with atopic eczema and the group without atopic eczema.

CONCLUSION

Patients with atopic eczema were overrepresented in the group of polysensitized patients and polysensitized patients should be viewed in the light of occurrence or lack of atopic eczema.

Sources of sensitization, cross-reactions, and occupational sensitization to topical anaesthetics among general dermatology patients

BACKGROUND

Contact sensitization to local anaesthetics is often from topical medicaments. Occupational sensitization to topical anaesthetics may occur in certain occupations.

OBJECTIVES

The aim of the study was to analyse the occurrence of contact sensitization to topical anaesthetics in general dermatology patients.

PATIENTS AND METHODS

Patch testing with topical anaesthetics was carried out in 620 patients. Possible sources of sensitization and the clinical histories of the patients are analysed.

RESULTS

Positive patch test reactions to one or more topical anaesthetics were seen in 25/620 patients. Dibucaine reactions were most common (20/25), and lidocaine sensitization was seen in two patients. Six patients had reactions to ester-type and/or amide-type anaesthetics concurrently. Local preparations for perianal conditions were the most common sensitizers. One patient had developed occupational sensitization to procaine with multiple cross-reactions and with concurrent penicillin sensitization from procaine penicillin.

CONCLUSIONS

Dibucaine-containing perianal medicaments are the major source of contact sensitization to topical anaesthetics. Although sensitization to multiple anaesthetics can be seen, cross-reactions are possible. Contact sensitization to lidocaine is not common, and possible cross-reactions should be determined when reactions to lidocaine are seen. Occupational procaine sensitization from veterinary medicaments is a risk among animal workers.

Trends of contact allergy to fragrance mix I and Myroxylon pereirae among Danish eczema patients tested between 1985 and 2007

BACKGROUND

Fragrance contact allergy has for long been recognized as an important health issue. In Denmark, the frequency of fragrance mix (FM) I contact allergy increased between 1985-1986 and 1997-1998 among male and female dermatitis patients.

OBJECTIVES

To investigate the development of FM I and Myroxylon pereirae (MP) contact allergy between 1985 and 2007 with an emphasis on recent years.

METHODS

A retrospective analysis of all patch test data from our database was performed. Comparison of sensitivity rates was made using a chi-squared test for trend. Logistic regression analyses were used to test for associations.

RESULTS

Of 16,173 patients, 7.2% were sensitized to FM I and 4% to MP. FM I contact allergy was associated with female sex [odds ratio (OR) = 1.52; 95% confidence interval (CI) = 1.33-1.74] and age between 41 and 60 years (OR = 3.20; 95% CI = 1.98-5.21). Significant declines of FM I and MP reactions among women but not men were observed between 1999 and 2007.

CONCLUSIONS

Although the frequency of FM I contact allergy has decreased in Denmark in recent years, it is still high. Furthermore, fragrance contact allergy is caused by other important allergens not included in this analysis. Allergic contact reactions to the ingredients of FM I remain a problem in European consumers.

New aspects in allergic contact dermatitis

PURPOSE OF REVIEW

To give selected new information on contact allergy and allergic contact dermatitis with focus on diagnostic procedures and pitfalls.

RECENT FINDINGS

Recent studies dealing with common contact allergens have improved our understanding of the relationship between positive patch tests and the clinical interpretation and consequences for the patient.

SUMMARY

Nickel allergy is still the most common contact allergy in Europe in spite of full implementation of the EU Nickel Directive in 2001. Contact allergens in cosmetics and topical drugs are another common cause of allergic contact dermatitis. The main culprits include fragrance chemicals, preservatives, and hair dyes. We are all more or less exposed to cosmetics and topical drugs on a daily basis. The labelling requirements given in the Cosmetics Directive is of great help in tracing the causative allergenic ingredients. Most of the components present in cosmetic products are also occurring in household and industrial products, often under other trade names. Patients with multiple contact allergies constitute a special problem because their quality of life is severely affected by the multitude of eliciting products in the environment. We still lack a good understanding of why these patients become so easily sensitized.