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 / Measured in people or real products
Fresh limonene and linalool rarely cause allergy; the allergens form when these chemicals react with air, which also happens in essential oils and perfumes during storage.
Strong evidence.
Caveats
A '0.1-0.3% of patients' figure was removed because it does not trace to a source in our evidence base. Parent-compound sensitization rates are low but vary by dataset; see the Dittmar 2019 entry for oxidized-terpene positive rates.
Source: Bråred Christensson 2016, Contact Dermatitis Industry-funded Link to this fact
Skin allergy / Measured in people or real products
In 2,900 dermatitis patients tested at nine clinics in Europe, Asia, and Australia, 6.9% were allergic to air-oxidized linalool, the form a common floral scent chemical found in most perfumes, cosmetics, and many cleaners takes after contact with air.
Strong evidence: Dermatitis patients, not general population; 72% weak reactions; range 3-14% by clinic.
Source: Christensson 2012, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
For people already allergic to oxidized linalool (the air-exposed form of a common floral fragrance chemical), using a scented cream or perfume containing it at concentrations similar to real products (as low as 0.3% oxidized linalool, 0.056% linalool hydroperoxides) was enough to trigger eczema within three weeks of twice-daily use in a repeated-use trial.
Strong evidence.
Caveats
Small N (6 completers); participants were pre-selected as already patch-test-positive, not a general-population sample; lowest concentration tested (0.1% in perfume) did not produce a formal positive.
Source: Andersch Björkman 2014, Contact Dermatitis Link to this fact
Skin allergy / Measured in people or real products
Standard allergy screening misses a large share of fragrance allergy: in one UK clinic 42% of patients allergic to at least one of the 26 EU-labeled fragrance chemicals tested negative on the standard fragrance markers, and about 4 in 10 people who reacted to their own perfume or deodorant were negative on the screen.
Moderate evidence.
Caveats
Comparator-dependent: Sukakul 2022 found ~10% missed when comparing fragrance mixes with their own ingredients (abstract-sourced). The Mann 2014 primary, now read in full (not just its abstract), confirms 203 patients reacted to any of the 26 EU fragrances and only 117 (57.6%) also reacted to a baseline marker = 42.4% missed; Mann's own Discussion states this as "40.6%" in one sentence, a small internal inconsistency in the primary (Results math gives 42.4%). More importantly, Mann's own paper reports a similarly-designed Danish study (Heisterberg 2011, n=1,508, also routine testing of all patients with the same 26 fragrances) that found only 15.6% missed — a ~2.5-fold discrepancy the authors attribute only partly to higher test concentrations and a different patient population, not fully resolved. The own-product figure (41%/45%) is from a different study (Uter 2007), not Mann.
Skin allergy / Measured in people or real products
Concentrations of hydroxycitronellal found in some 'natural' perfumes (up to 6.04%) exceeded the concentration shown to sensitize 36% of healthy volunteers in repeated-insult patch testing (5%), and were also well above the fragrance industry's own 1996 recommended maximum (equivalent to about 1% in the finished product).
Moderate evidence.
Caveats
Single-study 1996 patch-test-sensitization citations (Ford & Api 1988; Suskind 1992) for the 5%/36% figure, not independently verified in this evidence base; product concentration is not the same as measured consumer exposure dose.
Skin allergy / Other evidence
Fine fragrances (perfume, cologne) carry more contact-allergy risk per use than the same allergen amount spread over a larger, more dilute area, because sensitization risk depends on allergen dose per unit skin area, not total allergen delivered.
Moderate evidence: General dose-response principle from cited elicitation studies, not this review's own new experiment.
Source: Johansen 2003, Am J Clin Dermatol 4(11):789-798, American Journal of Clinical Dermatology Link to this fact
Skin allergy / Other evidence
The standard fragrance patch-test screen (fragrance mix I, fragrance mix II, balsam of Peru) misses a large share of true fragrance allergy: this review's own cited figures range from about 40% to 70% missed depending on the comparison, and "approximately half" of relevant reactions to perfumes, deodorants, and shaving lotions go undetected by baseline testing.
Moderate evidence.
Caveats
Different underlying comparators (26-fragrance panel vs hydroperoxides vs own products) give different miss rates; a specific percentage should always name what it was compared against.
Source: de Groot 2020, Dermatitis 31(1):13-35, Dermatitis® Link to this fact
Skin allergy / Other evidence
In a 4-year German patch-test study of 1,468 patients tested with their own deodorants and perfumes, 129 had positive reactions to a specific product, and 58 of them (45%) were missed by the standard fragrance-mix, balsam-of-Peru, and lyral patch tests.
Moderate evidence.
Caveats
Numbers relayed secondhand via this review, citing Uter et al.; the primary IVDK dataset is not yet in our evidence base, and the specific allergens responsible for the 58 missed reactions are not given.
Source: Martini 2020, Annales de Dermatologie et de Vénéréologie Link to this fact
Skin allergy / Other evidence
Among 442 Danish adults aged 28-30, only 0.7% tested positive to fragrance mix I, although 33.0% (293/889) said perfumed products had given them eczema.
Moderate evidence.
Caveats
Self-report is lifetime recall of any eczema from perfumed products; the patch panel was the narrow TRUE Test (no FM II, no own products, no day-7 reading), so the gap partly reflects test sensitivity and irritant reactions.
Source: Mortz 2013, British Journal of Dermatology 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 / 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 / Measured in people or real products
Skin care products caused the most cosmetic reactions (26%), then non-color hair preparations (16%) and facial makeup (12%); perfumes, colognes and toilet waters were only 7%.
Moderate evidence: Selected referral series of contact dermatitis specialists, 1977-1980 (40 months); not general-population rates.
Source: Eiermann 1982, Journal of the American Academy of Dermatology Link to this fact
Skin allergy / Review of other studies
Standard fragrance-allergy patch screening (fragrance mix I plus balsam of Peru) is estimated to identify only 60 to 70 percent of people with true fragrance allergy, due to the evolving ingredient mix used by the perfume industry.
Weak evidence: Secondhand figure relayed from the authors' ref. 11 (a NACDG/Scheman source), not independently verified or re-derived in this paper.
Source: Zirwas & Moennich 2008, The Journal of Clinical and Aesthetic Dermatology Link to this fact
Skin allergy / Self-reported survey
A previous rash from perfumed cosmetics was significantly associated with a positive patch test to the product perfumes (p = 0.001), suggesting the reactions were clinically relevant.
Weak evidence: Self-reported rash history; association test only, clinic patients.
Source: Johansen 1997, Contact Dermatitis Link to this fact
Skin allergy / Other evidence
36.4% of surveyed UAE women reported an adverse reaction to cosmetics in the past 2 years, mainly skin redness (20.6%), pimples (18.4%) and itching (16.9%); skincare (21.7%) and makeup (14.1%) were blamed far more often than perfume (5.2%).
Weak evidence.
Caveats
Open-link snowball sample of 461 women, mostly young and university-educated; self-report, no exposure measurement; not weighted, so not a UAE prevalence. Mixes fragrance-related and non-fragrance reactions (pimples, hair loss, pigmentation); attribution is the respondent's own.
Source: AlBlooshi 2026, Frontiers in Toxicology Link to this fact
Information, not medical advice. See also: myths we won’t tell you.