Hydroperoxides Of Linalool Research Articles

Results of patch testing propolis in the European baseline series: A 4-year retrospective study.

Propolis was added to the European baseline series (EBS) in 2019. To investigate the frequency and relevance of positive patch tests to propolis in the EBS and to study co-reactivities. Retrospective study in patients patch tested between June 2019 and November 2023 in a university hospital in Amsterdam, The Netherlands. Of 3134 consecutive patients, 299 (9.5%) had a positive reaction to propolis 10% pet. Only nine reactions (3%) were judged to be clinically relevant. There were significant co-reactivities to Myroxylon pereirae resin (balsam of Peru), colophonium, fragrance mixes 1 and 2, and to limonene and linalool hydroperoxides. A steep increase in rates of positive reactions to propolis was observed from 2020 to 2023. This was highly likely the result of the replacement of Chinese propolis with Brazilian propolis by the manufacturer. Positive patch tests for propolis are very frequent in Amsterdam, but only a few of these reactions are relevant. Most are probably (pseudo-)cross-reactions in patients with fragrance allergies. Propolis in the EBS has very limited value for dermatologists and patients in The Netherlands. Changes in patch test materials should be provided to all users to avoid misinterpretation of patch test results.

A lipidomic approach towards identifying the effects of fragrance hydroperoxides on keratinocytes.

Limonene and linalool are used in cosmetic products for their floral scents, but their oxidation products are strong contact allergens whose mechanisms of action are still not fully understood. The effects of limonene hydroperoxide (Lim-2-OOH) and linalool hydroperoxides (Lin-6/7-OOH) on the lipid profile of a human keratinocyte cell line (HaCaT) were evaluated. 2,4-Dinitrofluorobenzene (DNFB) was also included. Lim-2-OOH and Lin-6/7-OOH were synthesised according to previous methods. HaCaT cells were treated with allergens (10 μM) for 24 h and the cellular lipid extracts were analysed by C18 liquid chromatography with tandem mass spectrometry (LC-MS/MS). Data analysis was performed using Lipostar software. Statistical analysis was carried out using Metaboanalyst and R software. All three sensitisers used caused significant changes in the lipidome of HaCaT cells in a similar trend. There was an upregulation in several plasmanyl/plasmenyl phospholipids (O-/P-phosphatidylcholines [PC] and O-/P-phosphatidylethanolamines [PE]), sphingolipids (HexCer) and triacylglycerol lipid species, and a decrease in some polyunsaturated fatty acids-containing phospholipid (PE and PC) species suggesting oxidative stress and inflammation. This study is the first to evaluate the plasticity of the HaCaT cell lipidome in response to allylic hydroperoxide allergens Lim-2-OOH and Lin-6/7-OOH, together with the experimental contact allergen DNFB. These allergens are able to upregulate and downregulate certain lipid classes to a varying degree.

Patch Testing to Mentha piperita (Peppermint) Oil: The North American Contact Dermatitis Group Experience (2009-2020).

Background: Mentha piperita (MP; peppermint) oil has many commercial uses. Objective: To characterize the epidemiology of contact allergy to MP oil 2% petrolatum. Methods: Retrospective analysis of North American Contact Dermatitis Group data (2009-2020). Results: Of 28,128 patients tested to MP, 161 (0.6%) had an allergic reaction. Most allergic patients were female (77.0%) and/or over 40 years of age (71.4%). The most common anatomical sites of dermatitis included face (31.7%; of these, one-third specified lips), hands (17.4%), and scattered/generalized (18.6%). Nearly one-third (30.4%) of reactions were strong (++)/extreme (+++), and 80.1% were considered currently relevant. Common sources included oral hygiene preparations, foods, and lip products. Co-reaction with at least 1 of the other 19 fragrance/plant-related screening test preparations occurred in 82.6% (133/161) of MP-allergic patients, most commonly Cananga odorata oil (42.9%), fragrance mix I (41.0%), hydroperoxides of linalool (35.7%), Compositae mix (35.4%), Jasminum officinale oil (31.9%), Myroxylon pereirae (31.7%), and propolis (28.1%). Co-reaction with at least 1 of the 3 most commonly used fragrance screening allergens (fragrance mix I, fragrance mix II, and/or Myroxylon pereirae) was 59.6%. Conclusions: Twelve-year prevalence of MP allergy was 0.6%. Approximately 40% of cases would have been missed if only fragrance screening allergens were tested.

Characterization of Pediatric Patch Testing: A Retrospective Review, 2020-2023.

Background: Recent evidence shows similar rates of allergic contact dermatitis (ACD) among children and adults despite children accounting for less than 10% of patch testing subjects. With a need for in-depth analyses of pediatric ACD, we herein characterize a pediatric cohort at a large North American patch testing center. Methods: A retrospective chart review was conducted for 135 patients ages 1-17 years who underwent patch testing from July 2020 from August 2023. Data were stratified by age 1-5, 6-11, and 12-17 years. Significance-Prevalence Index Numbers (SPIN) were calculated. Results: A total of 86% were sensitized, 40% had a relevant reaction, and positivity rates were equal between males and females. Top allergens by SPIN differed with age, but overall were linalool hydroperoxides (SPIN = 11.01), propylene glycol (10.30), limonene hydroperoxides (10.27), fragrance mix I (5.62), and lanolin (4.90). In total, 14% of the top allergens were not represented on the North American Contact Dermatitis Group standard series. Of those tested to personal products, 45% had positive reactions and 72% of which were relevant. Conclusions: Emulsifiers and fragrances were the most relevant allergen categories, with the impact of emulsifiers not previously reported. ACD may affect males and females equally in this population. Supplemental allergens and personal products tested "as-is" contribute to conclusive pediatric patch testing.

Allergic Contact Dermatitis to Linalool Hydroperoxides: Pitfalls in the Diagnostic Process-Findings from a Repeated Open Application Test Study.

Background: Increasing trends of oxidized linalool contact allergy have been reported. However, the impact of reactivity and dose in eliciting allergic contact Dermatitis caused by linalool hydroperoxides is insufficiently investigated. Objectives: To perform repeated open application tests (ROATs) using the real-world concentrations of linalool hydroperoxides in patients and control participants. Materials and Methods: Patients who previously had a positive (patients) and a negative (controls) patch test reaction to linalool hydroperoxides 1.0% in petrolatum were patch tested with a dilution series of linalool hydroperoxides preparations and asked to perform ROAT twice daily with 3 concentrations of linalool hydroperoxides creams and a negative control cream for 28 days. The creams contain 44, 140, and 440 PPM of linalool hydroperoxides, representing real-world doses reported in consumer products. Results: Of all 47 participants, 31 were linalool hydroperoxides contact allergy patients, and 16 were controls. One patient had a positive ROAT reaction in the area where cream at the highest concentration of linalool hydroperoxides was applied for 28 days. Conclusions: Repeated exposure to creams containing linalool hydroperoxides at real-life concentrations could rarely elicit an allergic reaction on intact skin after 4 weeks.

Pediatric Patch Testing at Mayo Clinic Between 2016 and 2020.

Background: Allergic contact Dermatitis (ACD) is a common condition within the pediatric population. Patch testing is an important way to identify relevant allergens. Objective: To provide an update of the common contact allergens seen in children based on patch testing data at our institution from 2016 to 2020. Methods: We performed a retrospective analysis of patch test data from children aged 1-18 years from 2016 to 2020 at Mayo Clinic. Reaction rates were compared to the rates reported by the Pediatric Contact Dermatitis Registry (PCDR). Results: One hundred ninety-two children aged 1-18 were patch tested to various allergens. A total of 15,457 allergens were tested, with 291 positive tests. The top 5 allergens with highest positive reaction rates were hydroperoxides of linalool, hydroperoxides of limonene, methylisothiazolinone, nickel, and cobalt. Seven of the top 38 allergens with the highest reaction rates are not currently included in the Mayo Clinic Pediatric Patch Test Series, and 11 are not currently included in the Pediatric Baseline Series (as developed by the Pediatric Contact Dermatitis Workgroup). Conclusions: Patch testing is a useful tool to diagnose children with ACD. With new products and exposures, there is an opportunity to expand current pediatric patch testing series.

Allergic or Not: Final Interpretation of Doubtful Patch Test Reactions From the North American Contact Dermatitis Group, 2019-2020.

Background: Doubtful patch test reactions generally do not meet criterion for positivity in patch testing. However, the North American Contact Dermatitis Group (NACDG) allows for doubtful reactions to be coded with a final determination of "allergic/positive" based on the temporal pattern, appearance, known characteristics of the allergen, and/or other supportive patch test reactions. Objectives: To analyze NACDG data from the 2019-2020 patch test cycle to identify patterns in the interpretation and relevance of doubtful reactions. Methods: The frequency and proportions of doubtful reactions were tabulated and analyzed for patterns. Statistical analyses were limited to allergens with ≥30 doubtful reactions to ensure adequate sample size. Results: Of patch-tested patients, 31.9% (1315/4121) had ≥1 doubtful reaction. Of 2538 total doubtful reactions, 46% (n = 1167) had a final interpretation of "allergic/positive." The allergens with the highest proportion of doubtful reactions at the final visit were hydroperoxides of linalool 1% (4.5%), fragrance mix I 8.0% (3.9%), and cetrimonium chloride 0.5% (3.4%). Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) 0.02% (P < 0.001), MI 0.2% (P < 0.001), nickel sulfate hexahydrate 2.5% (P = 0.001), and neomycin sulfate 20.0% (P = 0.003) doubtful reactions were more likely to be interpreted as allergic than nonallergic. Methyldibromoglutaronitrile/phenoxyethanol 0.2% (P < 0.001), oleamidopropyl dimethylamine 0.1% (P < 0.001), formaldehyde 2.0% (P < 0.001), cetrimonium chloride 0.5% (P < 0.001), benzophenone-4 (sulisobenzone) 10% (P < 0.001), iodopropynyl butylcarbamate 0.5% (P < 0.001), cocamidopropyl betaine 1.0% (P = 0.002), and benzisothiazolinone 0.1% (P = 0.012) doubtful reactions were less likely to be interpreted as allergic. Of the 1167 doubtful reactions interpreted as allergic, 84.9% had current relevance. Conclusions: Doubtful reactions were common and approximately one half were coded with a final interpretation of "allergic/positive." Of those, most were clinically relevant. MCI/MI, MI, nickel, and neomycin were more likely to be interpreted as allergic.

Colophonium-related Allergic Contact Dermatitis Caused by Medical Adhesive Tape Used to Prevent Skin Lesions in Soldiers.

Medical adhesive tapes are commonly recommended for the prevention of friction blisters during hiking and military marches. The aim of this paper is to report on the results of investigations into an outbreak of tape-related foot dermatitis in 26 military conscripts following continuous use of medical adhesive tapes for several days during a field exercise. Patch tests were performed using baseline series and aimed testing was performed with colophonium-related substances and different medical adhesive tapes. Contact allergy to the adhesive tapes used was found in 20 (77%) subjects, and contact allergy to colophonium in 16 (61%). Chemical analysis detected colophonium-related substances in the culprit tapes. Compared with consecutive dermatitis patients investigated at our Department of Occupational and Environmental Dermatology in the previous 10 years, conscripts with colophonium allergy had increased odds ratios for concomitant contact allergy to phenol formaldehyde resins and fragrance substances including hydroperoxides of limonene and linalool. The results show that prolonged use of medical adhesive tapes on intact skin carries a high risk for allergic contact dermatitis. Prior to their introduction on the market, medical devices should be assessed for possible side-effects.

Patterns of simultaneous contact allergies in patients with contact sensitization to oxidised linalool and oxidised limonene.

Contact allergy rates of linalool and limonene hydroperoxides (HPs) have increased. To demonstrate the patterns of simultaneous positive patch test (PT) reactions and prevalences of multiple contact allergies (MCAs) in patients with contact allergy to linalool and/or limonene HPs. A retrospective analysis of consecutive dermatitis patients in 2015-2020 was performed. Of all 4192 patients, 1851 had at least one positive PT reaction. Of these, 410 (22.2%) had MCAs, significantly related to a higher age (p-value = 0.003). Patients with an exclusively positive reaction to linalool HPs but not limonene HPs were shown to have MCAs (p-value <0.001, odds ratio (95% confidence interval) = 4.15 (3.01-5.73)). Patients with simultaneous contact allergies to both linalool and limonene HPs had contact allergies to many other screening and fragrance allergens. Simultaneous positive PT reactions to allergens in baseline series and fragrances are common in patients with the HPs contact allergy, especially linalool HPs. The pattern of simultaneous PT reactions principally suggested the co-sensitization of the cosmetic allergens.

44254 Assessing clinical relevance of limonene and linalool hydroperoxides patch test positivity: a prospective series of 247 patients

44254 Assessing clinical relevance of limonene and linalool hydroperoxides patch test positivity: a prospective series of 247 patients

Patch Testing Results From the Massachusetts General Hospital Occupational and Contact Dermatitis Clinic, 2017-2022.

Background: Patch testing is gold standard for identifying the source of allergic contact dermatitis (ACD). Objective: To report patch testing results from the Massachusetts General Hospital (MGH) Occupational and Contact Dermatitis Clinic from 2017 to 2022. Methods: Retrospective analysis of patients referred to MGH for patch testing, 2017-2022. Results: In total, 1438 patients were included. At least 1 positive patch test (PPT) reaction was observed in 1168 (81.2%) patients and at least 1 relevant PPT reaction was observed in 1087 (75.6%) patients. The most common allergen with a PPT was nickel (21.5%), followed by hydroperoxides of linalool (20.4%) and balsam of Peru (11.5%). Sensitization rates statistically increased over time for propylene glycol and decreased for 12 other allergens (all P values <0.0004). Limitations: Retrospective design, single institution tertiary referral population, and variations in allergens and suppliers across the study period. Conclusion: The field of ACD is constantly evolving. Regular analysis of patch test data is crucial to identify emerging and diminishing contact allergen trends.

Patch testing hydroperoxides of limonene and linalool in consecutive patients-Results of the IVDK 2018-2020.

Hydroperoxides of limonene (Lim-OOHs) and linalool (Lin-OOHs) are potent contact sensitizers. To investigate the prevalence of positive patch test (PT) reactions to Lim-OOHs and Lin-OOHs in consecutive patients, their demographic factors and concomitant reactions. Between 7/2018 and 12/2020, Lim-OOHs 0.3% pet. and Lin-OOHs 1% pet. were patch tested in 5511 consecutive patients. We assessed PT reactivity and analysed data from patients with either positive or negative PTs to Lim-OOHs and Lin-OOHs. Positive PT results to Lim-OOHs (n = 170, 3.1%) and Lin-OOHs (n = 483, 8.8%) were frequent. Most of the positive reactions were weak (LimOOHs n = 134/LinOOHs n = 429), and even more frequently, doubtful (n = 252/n = 578) or irritant reactions (n = 81/n = 178) were documented. PT reactivity to Lim-OOHs and Lin-OOHs was increased in patients with irritant reactions to sodium lauryl sulphate (SLS). The proportion of leg dermatitis and concomitant positive reactions to fragrances and essential oils was increased in patients with reactivity to these hydroperoxides. The observed reaction pattern suggests that both test preparations display an irritant potential with an increased risk of false positive reactions. Preparations should be chemically monitored in order to reduce irritancy. Mindful interpretation of PT results and aimed patch testing of lower concentrations is recommended.

Trends in Patch Testing With the Mayo Clinic Standard Series, 2017-2021.

Background: Patch testing to a standard series is used to identify culprit allergens in patients with contact dermatitis. The reaction rates evolve over time based on trends in cutaneous exposures by the general population. Objective: The aim of this study was to analyze the patch test results of the Mayo Clinic standard series in patients tested from 2017 to 2021. Methods: The patch test reactions of standard series allergens tested from 2017 to 2021 were retrospectively reviewed and compared with the results of our prior report from 2011 to 2015 as well as the North American Contact Dermatitis Group (NACDG) report from 2017 to 2018. Results: Of 2667 patients tested, 1683 (63.1%) had at least 1 positive reaction. The 15 allergens with the highest reaction rates were hydroperoxides of linalool 1%, nickel (II) sulfate hexahydrate, methylisothiazolinone, Myroxylon pereirae resin, hydroperoxides of linalool 0.5%, methyldibromo glutaronitrile, neomycin sulfate, cobalt (II) chloride hexahydrate, fragrance mix I, benzalkonium chloride, bacitracin, hydroperoxides of limonene, methylchloroisothiazolinone/methylisothiazolinone, p-phenylenediamine, and textile dye mix. Twelve (80%) of these allergens were also in the top 15 of the most recent NACDG report. Conclusions: Hydroperoxides of linalool and hydroperoxides of limonene are new allergens that have been added to our standard series. These are associated with high reaction rates.

North American Contact Dermatitis Group Patch Test Results: 2019-2020.

Background: Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD). Objective: This study documents the North American Contact Dermatitis Group (NACDG) patch testing results from January 1, 2019, to December 31, 2020. Methods: At 13 centers in North America, patients were tested in a standardized manner with a screening series of 80 allergens, and, as indicated, supplemental allergens. Results: Overall, 4121 patients were tested; 2871 (69.7%) had at least 1 positive/allergic patch test reaction and 2095 patients (51.2%) had a primary diagnosis of ACD. The most commonly positive allergens were nickel (18.2%), methylisothiazolinone (MI) (13.8%), fragrance mix (FM) I (12.8%), hydroperoxides of linalool (HPL) (11.1%), and benzisothiazolinone (BIT) (10.4%). Compared with that of 2017-2018, prevalence of top 20 allergens statistically increased for FM I, HPL, BIT, propolis, and hydroperoxides of limonene (3.5%). For the first time, MI positivity did not increase between reporting periods. Approximately one-fifth of patients (20.3%) had ≥1 clinically relevant reaction(s) to allergens/substances not on the NACDG series. Conclusions: The epidemic of MI contact allergy in North America may have reached a plateau. Patch testing using a robust screening series, and supplemental allergens as indicated, is necessary for comprehensive evaluation of ACD.

Limonene and linalool hydroperoxides review: Pros and cons for routine patch testing.

Limonene and linalool are among the most common fragrance terpenes used in everyday products. They are pre-haptens, forming hydroperoxides (Lim-OOHs, Lin-OOHs) upon oxidation and inducing frequent positive patch test reactions in patients with dermatitis, and yet they are not routinely tested in Europe. This review evaluates current patch testing with Lim-OOHs and Lin-OOHs by asking whether hydroperoxide patch testing is warranted, examining the difficulties or challenges related to reading and interpreting hydroperoxide patch test results with currently available material, and assessing their relevance. Studies are increasingly pointing to high percentages of positive reactions in patients consecutively patch tested with these oxidized products. An association between a positive clinical history and a strong patch test reaction has been described, but problems with doubtful/irritant reactions have also been reported. Considering the high frequency of relevant positive reactions, the incorporation of Lim-OOHs 0.3% and Lin-OOHs 1% in the baseline series may be justified. Since exposure, sensitization, and elicitation limits of Lim-OOHs and Lin-OOHs in the products still need to be better determined, an assessment of previous exposure, possible sensitizations, and reactions may help to improve the clinical assessment.

What is the added value of patch testing with 30 fragrance allergens in addition to the European Baseline series?

BackgroundPatch testing with the fragrance allergy markers in the European baseline series (EBS) does not identify all patients with fragrance allergy. Hydroperoxides of linalool and limonene have been shown to be useful allergens in detecting fragrance sensitization.ObjectivesTo evaluate the added value of testing with 30 fragrance allergens in addition to the EBS.MethodsAll patients with suspected fragrance allergy who underwent patch testing at the Amsterdam University Medical Centers between November 2019 and January 2021 to the EBS and fragrance series were included.ResultsOf 323 patients tested, 162 (50.2%) were found to be fragrance sensitized. The most sensitizing single allergens were the hydroperoxides of linalool (1.0 and 0.5% pet.) and limonene (0.3 and 0.2% pet.). Testing with the hydroperoxides of linalool and limonene identified 62 fragrance‐sensitized patients (38.3%) who could not be detected by the common fragrance markers. Of all fragrance‐sensitized patients, 21 (13.0%) would have been missed when not testing with the fragrance series.ConclusionsPatch testing with the fragrance series in addition to the EBS is valuable. To reduce the risk of false‐negative reactions, it is advisable to test the hydroperoxides of linalool and limonene.

European patch test results with audit allergens as candidates for inclusion in the European Baseline Series, 2019/20: Joint results of the ESSCAA and the EBSB working groups of the ESCD, and the GEIDACC.

In 2019, a number of allergens (haptens), henceforth, "the audit allergens," were considered as potential additions to the European Baseline Series (EBS), namely, sodium metabisulfite, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, imidazolidinyl urea, Compositae mix II (2.5% or 5% pet), linalool hydroperoxides (lin-OOH), limonene hydroperoxides (lim-OOH), benzisothiazolinone (BIT), octylisothiazolinone (OIT), decyl glucoside, and lauryl glucoside; Evernia furfuracea (tree moss), was additionally tested by some departments as well. To collect further data on patch test reactivity and clinical relevance of the audit allergens in consecutive patients across Europe. Patch test data covering the audit allergens in 2019 and 2020 were collected by those departments of the European Surveillance System on Contact Allergies testing these, as well as further collaborators from the EBS working group of the European Society of Contact Dermatitis (ESCD), and the Spanish Grupo Español de Investigación en Dermatitis de Contacto y Alergia Cutánea. As patch test outcome, reactions between day (D) 3 and D5 were considered. Altogether n= 12 403 patients were tested with any of the audit allergen. Positive reactions were most common to lin-OOH 1% pet. (8.74% [95%CI: 8.14-9.37%]), followed by lin-OOH 0.5% pet., and lim-OOH 0.3% pet (5.41% [95% CI: 4.95-5.89%]). Beyond these terpene hydroperoxides, BIT 0.1% pet. was the second most common allergen with 4.72% (95% CI: 4.2-5.28%), followed by sodium metabisulfite 1% pet. (3.75% [95%CI: 3.32-4.23%]) and Compositae mix 5% pet. (2.31% [95% CI: 1.84-2.87%]). For some allergens, clinical relevance was frequently difficult to ascertain. Despite many positive patch test reactions, it remains controversial whether lin- and lim-OOH should be tested routinely, while at least the two preservatives BIT and sodium metabisulfite appear suitable. The present results are a basis for further discussion and ultimately decision on their implementation into routine testing among the ESCD members.

Safety Assessment of Citrus Flower- and Leaf-Derived Ingredients as Used in Cosmetics.

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 33 Citrus flower- and leaf-derived ingredients, which are most frequently reported to function in cosmetics as fragrances and/or skin-conditioning agents. The Panel reviewed the available data to determine the safety of these ingredients. Because final product formulations may contain multiple botanicals, each containing similar constituents of concern, formulators are advised to be aware of these constituents and to avoid reaching levels that may be hazardous to consumers. With Citrus flower- and leaf-derived ingredients, the Panel was concerned about the presence of the hydroperoxides of limonene and linalool in cosmetics. Industry should use good manufacturing practices to limit impurities that could be present in botanical ingredients. The Panel concluded that these ingredients are safe in the present practices of use and concentration when formulated to be non-irritating and non-sensitizing.

Contact allergy in a paediatric population observed in a tertiary referral centre in Belgium.

Contact allergy is increasingly recognized as being important in children with eczema. To retrospectively analyse the patch test results in children over the past 10 years, aiming to (1) evaluate demographic characteristics and lesion locations, (2) describe frequencies of positive patch test reactions, and (3) investigate the relationship with atopic dermatitis (AD). A total of 329 children were patch tested between January 2010 and December 2019 with the European (children) baseline series and/or other series, and the personal product(s) used. A total of 119 (36%) children presented with at least one positive reaction. Children with AD had a higher prevalence of positive reactions compared with the non-AD group (P=.002), but without statistically significant difference regarding sensitization to more than one hapten (P=.39). The face (20.2%), hands (19.3%), feet (16.8%), arms (12.6%), and body folds (10.9%) were the most common sites of primary localizations. The most frequent contact allergens were nickel sulfate and linalool hydroperoxide (both 16%), limonene hydroperoxide (13.5%), and para-phenylenediamine (10.9%). No statistically significant difference for nickel sulfate was found between the AD and non-AD group (P=.20). Contact allergy in children with eczema was frequently observed in our tertiary referral centre in Belgium as well, confirming the need for patch testing.

Facial contact dermatitis caused by cosmetic-relevant allergens.

Facial allergic contact dermatitis caused by cosmetic products is common. New allergens in cosmetics continuously emerge. To investigate characteristics of patients with facial dermatitis (FD) between 2010 and 2019 including patch test results from cosmetic-related allergens and a new test series with cosmetic-relevant natural ingredients (CRNIs). This is a retrospective study analysing demographics, clinical characteristics according to MOAHLFA index (male; occupation; atopic dermatitis; hand; leg; face; age ≥ 40 years), and patch test results to 27 cosmetic-relevant allergens in FD patients. A prospective study evaluating a screening test series with CRNIs in consecutive FD patients for 1 year was also conducted. These patients received a questionnaire for collecting extra characteristics (eg, concerning quality of life). Of 8740 tested patients, 2292 (26.2%) had FD. Of these, 30.6% had cosmetic-induced FD. The most common cosmetic-related allergens were fragrances and preservatives. The most common patch test-positive CRNIs were hydroperoxides of limonene and linalool, and propolis. Potato and peanut were rare, but the most common prick test-positive CRNIs, however, without any relation to the use of cosmetic products. FD affected nearly all patients' quality of life and caused limitations to their daily life. Updated management and quick diagnosis of FD is important to avoid negative impact on patients' quality of life.