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.
Fragrance is everywhere / Measured in people or real products
A lab analysis of 59 soaps, surface cleaners, laundry and dish-washing products from four European countries found the citrus-scent chemical limonene in 78% of them, linalool in 61%, and citronellol in 47%; all three are fragrance chemicals linked to skin allergy.
Moderate evidence: Products c. 2000, EU only; parent terpenes measured, not the allergenic oxidized forms; Unilever co-author.
Source: Rastogi 2001, Contact Dermatitis Industry-funded Link to this fact
Fragrance is everywhere / Measured in people or real products
A 2015 survey of 817 unique detergent products from 131 German households found limonene and linalool — the two fragrance chemicals most often linked to skin allergy when oxidized — named on 23.1% and 20.1% of product labels, more than any of the other 24 EU-declarable fragrance allergens.
Moderate evidence: Label-declaration frequency above the EU's 0.01% threshold, not a chemical measurement; Northern Germany, 2015, convenience sample, not representative.
Source: Wieck 2018, Regulatory Toxicology and Pharmacology Link to this fact
Fragrance is everywhere / Review of other studies
Burning, stinging, or itching sensations in the eyes, nose, and throat from airborne chemicals are caused by a specific, receptor-mediated nerve reflex (activation of TRPV1, TRPA1, TRPM8, and related channels on trigeminal nerve endings), not by allergy or immune response.
Moderate evidence.
Caveats
This is established sensory-irritation physiology synthesized from many primary studies the review cites, not new data from this paper; it describes the receptor mechanism, not whether any specific product or exposure reaches an irritating dose.
Source: Nielsen & Wolkoff 2017, Regulatory Toxicology and Pharmacology Industry-funded Link to this fact
Fragrance is everywhere / Measured in people or real products
Besides the fragrance-mix allergens, 14 other common fragrance materials (including linalool, benzyl acetate, and hedione) were found in 40-97% of the 73 deodorants tested in 1996; for three of them (hedione, linalyl acetate, alpha-isomethyl ionone) no published human contact-allergy case existed at the time despite their widespread use.
Moderate evidence.
Caveats
Absence of published reports as of 1998 is not the same as absence of risk; testing history for these three substances specifically was not systematically reviewed by the authors beyond a literature check.
Source: Rastogi et al. 1998, Contact Dermatitis Link to this fact
Fragrance is everywhere / Measured in people or real products
Because most cosmetics contain fragrance, the dermatologists noted that fragrance allergy is not limited to fragrance products: fragrance ingredients were the commonest allergen group even though perfumes and colognes were only 7% of reactions.
Moderate evidence.
Caveats
Authors' inference from a selected series; 39 reactions were to unspecified fragrance and 77 to individually identified fragrance ingredients, with the 77 not reproducible from the printed table.
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.