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
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
Information, not medical advice. See also: myths we won’t tell you.