Don’t take our word for it. Here’s every fact on this site, with its evidence grade, its caveats, and a link to the source, so you can check us.
We start you on the strong ones: findings that have been replicated or come from one large, well-controlled study. Moderate and weak facts are here too, labeled for what they are. Use “Link to this fact” to share a single card.
Skin allergy / Other evidence
Patch-test studies cited by the report found 0.4 to 6.7% of people with no allergy history reacting to disperse dyes (Germany 1.35% of 24,980; Italy 6.7% of 6,478), while patch-test positives were much more common in people with an allergy history.
Moderate evidence: Secondary relay of a 2013 review of 54 studies with different dyes, purity and test methods; impure test dyes can inflate positives.
Source: Danish EPA 2014, Survey of Chemical Substances in Consumer Products No. 129 Link to this fact
Skin allergy / Other evidence
EWG Verified cleaners must label 26 fragrance allergens on the package at 0.01 percent (0.001 percent for hand dish soap, hand laundry detergent, and leave-on pet products), and post about 57 more on the product website.
Moderate evidence: The on-pack list is the pre-2023 EU 26; current EU cosmetics law requires about 80 on pack. The website list has a one-year phase-in and EWG reserves a transition period.
Source: EWG Verified criteria for cleaning products (10.24), Environmental Working Group, 2024 Link to this fact
Skin allergy / Other evidence
In North American patch-test clinics, about 1.6-1.7% of routinely tested patients reacted to toluene-2,5-diamine sulfate, a permanent hair-dye ingredient, and about 7 in 10 of them had a current link to a product they used.
Moderate evidence: Referred patients, not the general population; 2021-2022 cycle is unpublished personal communication; review of surveillance data by the Society that named the allergen.
Skin allergy / Other evidence
People allergic to PPD hair dye often react to the substitute dye ingredients too: in studies from 1997 to 2020, 31-76% of PPD-allergic patients also reacted to PTD or PTDS, so a substitute should be patch tested first.
Moderate evidence: Mostly older clinic series (all but IVDK tested 2009 or earlier); wide range between studies and between PTD and PTDS.
Skin allergy / Other evidence
Hairdressers carry a higher hair-dye allergy burden: hand dermatitis risk 1.7-2.5 times the general population, and 15.3% of 300 Spanish hairdressers patch-tested positive to PTDS.
Moderate evidence: Selected, older hairdresser series (1994-2016) with different test panels; rates vary widely between series.
Skin allergy / Other evidence
GOTS prohibits dyes "with allergenic potential (e.g. some disperse dyes)" in dyeing and printing and sets a residue limit of "< 20 mg/kg", defining them as H317 skin sensitizers linked to reported allergic contact dermatitis.
Moderate evidence.
Caveats
The list of named dyes is in a separate Implementation Manual not captured here; the text also lets H317 chemicals be handled with occupational safety practices, so how the ban works in practice is not shown.
Source: GOTS 8.1 (2026) Link to this fact
Skin allergy / Other evidence
The OEKO-TEX STANDARD 100 document says test samples with "a non-product typical odor (for example fragrance / perfume, mold)" are excluded from testing and cannot get the label.
Moderate evidence: A sensory screen on the submitted sample, not a chemical limit; no fragrance ingredient, allergen or ppm cap is named. Industry-run voluntary scheme.
Source: OEKO-TEX Standard 100 (2026) Industry-funded Link to this fact
Skin allergy / Other evidence
EWG says common hair-dye ingredients include p-phenylenediamine and resorcinol (skin irritation, allergic reactions, potential cancer risk), isothiazolinones such as methylisothiazolinone (strong sensitizers) and formaldehyde-releasing preservatives such as DMDM hydantoin.
Moderate evidence.
Caveats
Consumer advice from an advocacy group; sensitizer status of PPD and MI is well supported elsewhere in our evidence base, but the cancer wording is only 'potential' or 'associated with'.
Source: EWG 2025 (Friedman & Huang), EWG news (web page) Link to this fact
Skin allergy / Review of other studies
The outer layer of skin is held together by a fat mix in which ceramides make up about half the lipids, together with cholesterol and free fatty acids in roughly a 2:1:1 ratio, packed in layers between dead skin cells.
Moderate evidence: Narrative review by one author; the 2:1:1 ratio is approximate and cites 1980s analyses.
Source: Berdyshev 2024, Allergy, Asthma & Immunology Research Link to this fact
Skin allergy / Review of other studies
In eczema, skin ceramides are shorter and scarcer, partly because the immune signals IL-4 and IL-13 switch off the enzymes (ELOVL3/ELOVL6) that lengthen fatty acids, and they also suppress the barrier protein filaggrin.
Moderate evidence: Mechanism drawn from keratinocyte and skin-equivalent work plus clinical lipidomics; author discloses grants from Sanofi-Genzyme and LEO Pharma.
Source: Berdyshev 2024, Allergy, Asthma & Immunology Research Link to this fact
Skin allergy / Other evidence
The EU committee judged the three conditioner quats non-sensitizing: limited positive guinea-pig challenge reactions were read as irritation, and two human repeated-insult patch tests found cetrimonium chloride non-sensitizing up to 3.4%.
Moderate evidence.
Caveats
Animal tests had gaps the committee itself lists (missing positive-control data, one study unusable for hazard assessment); the human tests were industry-run and the committee calls predictive human sensitization tests unethical; applies to these three salts, not benzalkonium chloride.
Source: SCCS 2009 trimoniums, SCCS opinion (PDF) Link to this fact
Skin allergy / Other evidence
Cetrimonium chloride irritated human skin in patch tests at 3.5-8.8% (4-h patch, moderate irritant) and slightly to moderately at 3.25% (24 h), while 1% and below was non-irritating, so irritation from these hair-conditioning salts is concentration dependent.
Moderate evidence: Many entries are industry or manufacturer test summaries with sparse methods; vehicle and subject numbers often missing. CIR is industry funded.
Source: CIR 2010 trimoniums (draft) Industry-funded Link to this fact
Skin allergy / Other evidence
In rabbit eye tests reported by the EU's SCCP (2006), cetrimonium chloride at 25-29% active and behentrimonium chloride at 8% active caused irreversible eye damage, and behentrimonium chloride at 3% caused transient irritation; these are concentrated-material tests, not finished-product exposures.
Moderate evidence.
Caveats
Animal data relayed from the EU SCCP opinion; concentrations above most finished-product levels. CIR is industry funded. The CIR 2010 draft's 10%/6.25%/3% figures belong to behentrimonium chloride solutions (8/5/3% active), not cetrimonium chloride.
Source: CIR 2010 trimoniums (draft) Industry-funded Link to this fact
Skin allergy / Other evidence
Behentrimonium chloride gave mixed sensitization results: one guinea pig maximization-type study (10% induction) concluded it was a sensitizer, a Buehler test at 20% was negative, and human repeat-insult testing of a 3.4% rinse-off formulation (n = 104) showed no sensitization.
Moderate evidence.
Caveats
Industry-reported dossier data via SCCP; the human test is one formulation without full details, and no case reports of allergy to behentrimonium chloride are in the packet. CIR is funded by the Personal Care Products Council.
Source: CIR 2010 trimoniums (draft) Industry-funded Link to this fact
Skin allergy / Other evidence
The industry panel's 2010 draft contains no toxicology data at all for behentrimonium methosulfate, a widely used conditioning ingredient (conditioners 0.1-10%, baby products 0.3%); it was folded in by structural similarity to the chloride salt.
Moderate evidence: Absence in a draft packet; later CIR text may add data. Read-across from the chloride salt may be reasonable chemically but is not testing.
Source: CIR 2010 trimoniums (draft) Industry-funded Link to this fact
Skin allergy / Government agency
About 1 in 6 European eczema patients (about 16%) is sensitized to fragrance ingredients, and the EU committee estimated 1-3% of the general European population, a figure it said may be higher because only eight common allergens were tested.
Moderate evidence.
Caveats
Population figure comes from a few population-based studies using fragrance mix I only; later work finds higher figures with wider marker sets; clinic figure is a selected patient group.
Skin allergy / Measured in people or real products
In a Dutch cohort of 446 apprentice nurses followed for 1-3 years of traineeships, a history of atopic dermatitis roughly 2.5-fold raised the odds of hand eczema (weighted OR 2.5, 90% CI 1.7-3.7) after adjusting for hand washing and FLG status; 29% reported hand eczema at least once.
Moderate evidence.
Caveats
Single cohort of apprentice nurses (about 50% participation, 150 lost to follow-up); AD and hand eczema are self-reported and 90% CIs are used; irritant, allergic and atopic hand eczema were not distinguished.
Source: Visser et al. 2014, Contact Dermatitis, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
In the same nurse cohort, hand washing more than 8 times per shift at work (OR 2.2, 90% CI 1.2-4.2) and more than 10 times per day at home (OR 1.8, 90% CI 1.1-2.9) increased the odds of hand eczema during traineeships.
Moderate evidence: Workplace hand washing was assigned from healthcare-sector averages, not counted per person; single cohort; 90% CIs; not tied to any particular soap or product.
Source: Visser et al. 2014, Contact Dermatitis, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
Apprentice nurses with a history of hand eczema had far higher odds of hand eczema during traineeships (OR 4.5, 90% CI 2.96-6.98), and about 47% of them reported an episode in the first traineeship (about, read from Fig. 1) versus about 17% of those without a history.
Moderate evidence: Includes some people whose existing eczema continued; OR fell to 2.9 (90% CI 1.80-4.70) after excluding 20 such cases; figure values are approximate; single cohort.
Source: Visser et al. 2014, Contact Dermatitis, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
In this prospective nurse cohort, carrying a filaggrin (FLG) loss-of-function mutation without a history of atopic dermatitis did not raise hand eczema risk (adjusted OR 0.7, 90% CI 0.3-1.7), whereas FLG carriers who also had atopic dermatitis had the highest odds (OR 3.6, 90% CI 1.7-7.5).
Moderate evidence.
Caveats
Only 28 FLG+/AD+ and 38 FLG+/AD- subjects, so CIs are wide; the interaction test was not significant overall (OR 2.1, 90% CI 0.6-7.1); the authors' own case-control study found an FLG effect (OR 1.6), see the register entry.
Source: Visser et al. 2014, Contact Dermatitis, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
In one tertiary referral clinic's 821 consecutive dermatitis patients, 9.4% reacted to limonene hydroperoxides and 11.7% to linalool hydroperoxides, the allergens that form when these scent chemicals react with air; most reactions were weak.
Moderate evidence.
Caveats
Single tertiary referral center, so higher than the 2.5-5.4% and 3.9-7.7% the authors cite from other studies; the patients were already suspected of contact allergy, not the general public; a further 17% and 22% of readings were doubtful. Test preparations were bought from Chemotechnique and the authors declare no conflicts.
Source: Dittmar & Schuttelaar 2019, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
About 40% of the hydroperoxide patch-test reactions (limonene 40%, linalool 47%) were judged probably or certainly relevant to the patient's dermatitis, and about 20% certainly.
Moderate evidence: Relevance was judged from history and from patients checking labels for limonene or linalool; the hydroperoxides were never measured in the products and no use test was done.
Source: Dittmar & Schuttelaar 2019, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
Patients allergic to these hydroperoxides were more often female (odds ratio 1.9) and aged 40 or older (odds ratio 1.9), and a large share (76%) had other contact allergies too.
Moderate evidence: Odds ratios within one referral population of patch-tested patients; not a population risk estimate.
Source: Dittmar & Schuttelaar 2019, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
FDA says oxybenzone is a contact allergen for people with pre-existing skin conditions and a photoallergen for people with photosensitivity, and it would consider requiring allergy labeling if the missing data supported GRASE.
Moderate evidence.
Caveats
The patch-test rate is low overall and reflects a general allergy-clinic population; FDA calls the photoallergen evidence "clear" for photosensitive people only. Labeling is a possibility under the proposal, not a requirement.
Source: FDA proposed order OTC000008 (2021) Link to this fact
Skin allergy / Other evidence
A 2021 systematic review of 48 occupational studies rates the evidence that frequent wet work (repeated handwashing, wet hands) causes mostly minor irritant hand dermatitis as strong, and found no threshold below which wet work is safe.
Moderate evidence.
Caveats
A review of mostly cross-sectional worker studies with self-reported exposure; none was of the highest quality (3 of 21 wet-work studies rated high); the evidence grade is the authors' own on a Danish scale; no meta-analysis; Danish government research-fund funded, no industry funder.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Other evidence
In healthcare worker studies, hand dermatitis rose with the number of handwashes per day (for example US workers washing 10 or more times a day had about 1.95 times the incidence, and Korean nurses washing more than 30 times a day had an odds ratio of 13), while alcohol-based hand rub was not associated with hand eczema in several studies.
Moderate evidence.
Caveats
Individual cohort and cross-sectional studies summarized by the review; Korean figure is from self-reported hand eczema with wide confidence interval; two follow-up studies found non-significant ratios; some healthcare studies found no association with duration of washing.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Other evidence
The review rates detergents and non-alcoholic disinfectants as moderate evidence for irritant contact dermatitis on their own, and strong evidence when combined with other wet work, because in most studies the exposures cannot be separated.
Moderate evidence: Studies restricted to detergents or disinfectants alone varied; evidence is from occupational settings (hospital, cleaning, rubber, hairdressing), not home use.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Other evidence
The review found strong evidence that complete healing of occupational irritant contact dermatitis is poor when exposure continues unchanged, and moderate evidence that healing is better after changing job or work tasks; in the largest Danish cohort 15% healed and 52% improved in those who stayed in their profession versus 19% and 67% who changed profession (4-5 years).
Moderate evidence.
Caveats
Follow-up cohorts of specialist-clinic or recognized cases, probably the most severe; mostly self-reported outcome; four studies found no link between healing and job change; the evidence for partial improvement was rated only limited.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Other evidence
Atopic dermatitis is described as a susceptibility factor for irritant hand eczema (odds ratio about 3 when treated atopic disease), yet in this review's exposure-response analyses accounting for atopy did not change the association, and the authors note atopic people tend to avoid irritant trades.
Moderate evidence.
Caveats
The 3-fold figure is cited background, not a pooled estimate from this review; the review gives no evidence grade for atopy as a risk factor; most studies were cross-sectional and had limited atopy adjustment.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Other evidence
The review rates evidence that occlusive gloves alone cause irritant contact dermatitis as limited and gloves combined with other irritants as moderate; the authors say they cannot give specific advice on gloves as either protective or a risk factor.
Moderate evidence: Studies were split, some showing protection and some harm, with possible reverse causation in cross-sectional designs.
Source: Jacobsen 2022 Link to this fact
Skin allergy / Review of other studies
Sulfite contact allergy is easy to miss because sulfites are not in the T.R.U.E. test or the ACDS Core Allergen Series, so standard patch testing never checks for them.
Moderate evidence: The authors argue for adding sulfites to screening series; testing needs sodium disulfite 1% in petrolatum, not water.
Source: Choi 2024, Cutis Link to this fact
Skin allergy / Other evidence
Skin allergy to sulfites most often shows up on the face (28.8%) and hands (20.5%); sulfites can also cause a body-wide rash after being swallowed, injected or given rectally.
Moderate evidence: Site data come from one NACDG report; systemic cases are individual case reports.
Source: Choi 2024, Cutis Link to this fact
Skin allergy / Measured in people or real products
In a Danish clinic study of about 1,000 consecutive eczema patients, 4.2% (21/498) reacted to the perfume of at least one of 9 popular lower-priced wash-off products and 3.2% (16/497) to at least one of 8 stay-on products, patch tested at 5% in petrolatum.
Moderate evidence: Clinic population, not general population; the two product groups were tested at different clinics, so they are not directly comparable; one manufacturer's perfumes.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
The standard fragrance mix detected 81.3% (13/16) of positive reactions to stay-on product perfumes but only 52.4% (11/21) of those to wash-off product perfumes, and balsam of Peru added just 1 case, so patients with suspected perfume allergy need their own products tested.
Moderate evidence.
Caveats
Two clinics, different patch-test systems (TRUE Test vs petrolatum); single-group study not independently replicated for these product types; 10% of Odense candidates declined, many FM positive.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
Only about 31% (13/42) of fragrance-mix-positive patients in one clinic and 73% (11/15) in the other reacted to any of the product perfumes, so a positive fragrance mix does not predict reaction to a given product.
Moderate evidence: Different clinics and products; authors do not know whether it reflects low reactivity at product concentrations or a different allergy type.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
Among 758 recognized occupational hand eczema cases in Denmark (2001-2002), about 62% were purely irritant (mostly water and soap, i.e. wet work), about 21% purely allergic, and about 9% both.
Moderate evidence.
Caveats
Recognized/notified cases in one country only; irritant dermatitis is an exclusion diagnosis (no relevant positive patch test plus irritant exposure), so the split is definition-dependent.
Source: Skoet 2004, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
Fragrance was a minor cause of occupational contact allergy in Danish recognized hand eczema: 11 of 758 cases (1.2%), all women, linked to cleansing agents, cosmetics and other exposures.
Moderate evidence: Small count; recognized cases only; fragrance/balsam of Peru allergy without occupational relevance was more common (48 cases, 6.3%).
Source: Skoet 2004, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
In a Heidelberg patch-test study of 78 rosacea patients, 63% (49) reacted to at least one allergen, and balsam of Peru, a fragrance-related resin, was positive in about 10%, roughly 4 times the rate in a general-population sample (2.4%).
Moderate evidence: Single-center, 78 patients, wide CIs (4.6-19.4%); older patients; the authors say the source of balsam of Peru exposure is unexplained and call for confirmation.
Skin allergy / Other evidence
People with rosacea had very reactive skin: 70% (54 of 77) showed at least a slight irritant reaction to the lowest tested concentration of sodium lauryl sulfate (0.25%), against about 25% in a large reference study.
Moderate evidence: Small single-center sample; comparison group is a different study; measures nonspecific irritability, not allergy.
Skin allergy / Other evidence
Fragrance ingredients (161) and preservatives (149) were the two largest causes among 536 identified ingredient reactions in a US cosmetic dermatitis series (1977-1983).
Moderate evidence: Referral population; 67 of the 161 fragrance reactions could not be assigned to a component; historic test panels.
Source: Adams & Maibach 1985, Journal of the American Academy of Dermatology Link to this fact
Skin allergy / Other evidence
Quaternium-15 was the single most frequent identified preservative allergen (65 reactions), ahead of imidazolidinyl urea (21), parabens (19), bronopol (16) and formaldehyde (16).
Moderate evidence: Single 1977-1983 US referral series; usage patterns have changed.
Source: Adams & Maibach 1985, Journal of the American Academy of Dermatology Link to this fact
Skin allergy / Other evidence
A pooled analysis of 64 unpublished studies commissioned by a sunscreen maker found that about 1 in 400 healthy adults (48 of 19,570) had any possible irritation or allergic reaction to oxybenzone sunscreens under exaggerated patch-test conditions, and oxybenzone itself was confirmed as the cause in only 8 people.
Moderate evidence.
Caveats
Funded and written by the manufacturer's current and former employees (Schering-Plow HealthCare); data unpublished and unreviewed at study level; healthy volunteers only; some flagged subjects were never resolved. Industry position, not an independent incidence estimate.
Source: Agin 2008 (oxybenzone HRIPT), Photodermatology, Photoimmunology & Photomedicine Industry-funded Link to this fact
Skin allergy / Review of other studies
About 1 in 10 adults has hand eczema in any given year (1-year prevalence 9.7% median, 9.1% weighted across general-population studies, mostly Scandinavian); about 15% have had it at some point.
Moderate evidence: Mostly Scandinavian, self-reported questionnaires with varying definitions; unsystematic search; the authors think the true 1-year figure may be 12-15%.
Skin allergy / Other evidence
Women get hand eczema about twice as often as men (1-year prevalence about 11% vs 5-6%; new cases about 9.6 vs 4.0 per 1000 person-years), mainly because of different home and work exposures and eczema history, not because of skin susceptibility.
Moderate evidence: The exposure explanation is the authors' reading; self-reported data; the sex gap is largest in people under 30.
Skin allergy / Review of other studies
Hand eczema tends to be long-lasting: average duration is over 10 years, about 20% take sick leave of a week or more, and about 10% change jobs.
Moderate evidence: Mostly from two or three Scandinavian cohorts; sick-leave figures vary widely (a Norwegian survey found only 0.7-1.4% over 3 years); self-reported.
Skin allergy / Measured in people or real products
In a Danish university clinic, 15.7% of 6,004 consecutive dermatitis patients (2010-2015) were allergic to at least one of the 26 fragrance chemicals that EU cosmetics must name on the label.
Moderate evidence: Single clinic of patients referred for dermatitis, not the general population; 25 of the 26 allergens tested.
Skin allergy / Measured in people or real products
The most common single fragrance allergens among 6,004 consecutive dermatitis patients were oxidized linalool (3.9%), tree moss (3.0%), oxidized limonene (2.5%) and the synthetic HICC (2.1%); three of the four are not part of either standard fragrance mix.
Moderate evidence: One clinic; oxidized terpenes were tested only from 2012 (4,194 patients); other series report higher oxidized-terpene rates, so the ranking is clinic-specific.
Skin allergy / Measured in people or real products
The two standard fragrance mixes pick up only about 30% of patients allergic to oxidized linalool or oxidized limonene and about half of those allergic to tree moss, so a mixes-only screen misses most of them.
Moderate evidence: Single clinic; mixes compared with a clinic-chosen set of allergens; doubtful readings counted as not positive.
Skin allergy / Measured in people or real products
Oxidized linalool and oxidized limonene stayed well above the 0.5-1% positive rate that justifies routine testing in this clinic, even after falling from their first-year peak.
Moderate evidence: Single center; 20.9% and 13.7% of readings were doubtful, and some may be irritant rather than allergic.
Skin allergy / Measured in people or real products
Among patients allergic to the single ingredients of fragrance mix I, 92% also reacted to the mix, but only about one-third (32.7%) of mix-positive patients reacted to any ingredient; for fragrance mix II the figure was 57.0%.
Moderate evidence: Single clinic; ingredient test concentrations for FM I were lower than in some other series, which may reduce yield.
Skin allergy / Other evidence
Among 1,758 adult dermatitis patients referred for patch testing in Denmark, England, Spain and Germany, about 1 in 7 (259, 14.7%) reacted to at least one common fragrance allergen.
Moderate evidence: Referred patch-test population, not the general public; the share tested with the extended 26-allergen series varied by center.
Source: Bennike et al. 2019, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
Among fragrance-allergic patients whose eczema was attributed to fragrance and who had current eczema, the hands (40%) and face (34%) were most often affected.
Moderate evidence: Dermatologist-recorded final assessment in one referred patch-test cohort; patients could have several sites.
Source: Bennike et al. 2019, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
The main US dermatology society's extended allergy-test panel now uses air-oxidized limonene (0.2%) and linalool (0.5%) rather than the fresh chemicals, because testing the oxidized form finds more relevant reactions.
Moderate evidence: Committee consensus relaying two de Groot 2019 reviews, not new data; the US doses are lower than the European EECDRG doses (1% and 0.3%) because of irritant-reaction risk.
Skin allergy / Other evidence
A limited 36-allergen patch test such as the TRUE Test identifies about two-thirds (66%) of the clinically relevant reactions found by the broader North American screening series, so an extended panel finds more.
Moderate evidence: Secondary citation inside a committee consensus; the 66% comes from one cited review.
Skin allergy / Other evidence
The society dropped the preservative methyldibromoglutaronitrile from its extended allergy panel after EU restrictions (2005 leave-on, 2008 wash-off), judging it no longer usually clinically relevant; only 4% of products in the CAMP database (237 of 5,551) potentially contain it.
Moderate evidence: Based on committee clinical experience; most NACDG positives were of possible, past or unknown relevance, and the Euxyl K400 mix confounds the data.
Skin allergy / Other evidence
About 1 in 10 people referred to North American skin-allergy clinics and patch tested in 2021-2022 (308 of 3,040, 10.1%) reacted to hydroperoxides of linalool, the air-oxidized form of a very common scent chemical; 5.7% (173 of 3,047) reacted to oxidized limonene.
Moderate evidence.
Caveats
Referral clinic patients, not the general public; most reactions were weak (+) or doubtful, and the authors say it is unclear whether these reflect true allergy or irritation (irritant reactions 2.0% and 0.9%). Single network, one two-year cycle.
Skin allergy / Other evidence
Fragrance mix I (7.9%), balsam of Peru (7.0%), oxidized linalool (10.1%) and oxidized limonene (5.7%) are all among the 11 most common patch-test allergens in a 3,056-patient North American clinic series, and fragrance markers hold 5 of the 15 highest significance-prevalence scores.
Moderate evidence: Referral population; SPIN weights relevance judged by each clinician, mostly 'possible' relevance, without confirmatory use tests.
Skin allergy / Other evidence
Positive reactions to the two older fragrance-screening mixes fell to record lows in North America between 2019-2020 and 2021-2022 (fragrance mix I 12.8% to 7.9%, fragrance mix II 5.2% to 3.0%), while oxidized limonene reactions rose from 3.5% to 5.7% and balsam of Peru stayed flat (7.4% to 7.0%).
Moderate evidence.
Caveats
Same referral network but membership changed (6 centers left, 5 joined, about 25% fewer patients); 2019-2020 was an unusually high FM I cycle (12.8% vs 9.2% in 2017-2018); no multiple-comparison correction. The authors' explanations (atranol/chloroatranol limits, lyral ban) are untested.
Skin allergy / Other evidence
Fragrance allergy in North America is still very common but the markers that detect it are changing: the classic fragrance mixes are falling while terpene-hydroperoxide markers hold or rise.
Moderate evidence: Interpretive; the authors do not show that total fragrance allergy is unchanged, only that markers differ.
Skin allergy / Other evidence
More than 1 in 5 patch-tested patients (640 of 3,056, 21.1%) had a clinically relevant reaction to something outside the standard 80-allergen series, most often a personal care product or cosmetic (53.8% of those reactions), so a negative standard panel does not rule out a product allergy.
Moderate evidence: Relevance judged by the treating clinician; the specific allergens were not recorded; referral population.
Information, not medical advice. See also: myths we won’t tell you.