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
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
Hidden ingredients / Review of other studies
A violet-water cologne that doctors reported as a lavender-oil exposure in a boy with breast growth declared no essential oil on its ingredient list, and an essential-oil industry group's lab analysis found none; it reported a synthetic fragrance allergen (alpha-isomethyl ionone), azo dyes, and diethyl phthalate instead. Go by the ingredient list of the actual product, not its scent name.
Moderate evidence.
Caveats
Industry-funded letter (Consortium Huiles Essentielles, Giroux & Orjubin 2020), results as prose with no concentrations, detection limits, lab or sample provenance; not independently confirmed. The label did not claim lavender, so this is not a mislabeling example.
Source: Braunstein & Braunstein 2023, touchREVIEWS in Endocrinology Industry-funded Link to this fact
Hidden ingredients / Review of other studies
Sanitary pads, panty liners and tampons can contain undisclosed fragrance allergens, chiefly alpha-isomethyl ionone (in every scented tampon tested), hexyl cinnamal and benzyl salicylate, plus trace limonene, linalool and geraniol, and in the EU they do not have to declare any of them.
Moderate evidence.
Caveats
Primary source (Desmedt 2020, validated HS-GC-MS/FID, 10 scented Belgian AHPs) now in our evidence base. The compounds actually found above the EU 10 ug/g labeling threshold were alpha-isomethyl ionone (all 4 tampons, 12.6-19.1 ug/g), hexyl cinnamal, and benzyl salicylate (one panty liner); limonene, linalool and geraniol were all trace (<10 ug/g) — the original claim named the wrong allergens as the notable ones. Graded moderate: rests on one product-testing study relayed through a review.
Source: Pastor-Nieto 2021 (Desmedt 2020), Current Treatment Options in Allergy Link to this fact
Hidden ingredients / Measured in people or real products
In one of the best-known reports linking 'lavender' products to breast growth in children, the boy's violet-water cologne declared no essential oil on its ingredient list; the essential-oil industry's own analysis found none, but reported a synthetic fragrance allergen (alpha-isomethyl ionone), azo dyes, and diethyl phthalate, a fragrance solvent suspected of hormone disruption.
Moderate evidence: Industry-funded letter; GC-MS/LC-MS/MS results given as prose with no concentrations, detection limits, lab or sample provenance; not independently confirmed.
Source: Giroux & Orjubin 2020 (JCEM letter; Consortium Huiles Essentielles), The Journal of Clinical Endocrinology & Metabolism Industry-funded Link to this fact
Hidden ingredients / Measured in people or real products
The fragrance allergens found most in scented tampons were α-isomethyl ionone (in every tampon, 12.6-19.1 µg/g) and hexyl cinnamal, not the familiar citrus and lavender terpenes.
Moderate evidence: N=4 tampons, Belgian market; limonene/linalool may be under-read by a headspace method that sees parents only.
Fragrance is everywhere / Government agency
Alpha-isomethyl ionone, an allergen on the EU's 1999 labeled list, was declared on 46.6% of 88 deodorants checked in 2007 and detected in about 65% of 23 analyzed deodorants (6-2,588 ppm); it was found in 21.7% of 516 consumer products in another survey.
Weak evidence.
Caveats
Small, older market surveys cited from other authors (German/Danish samples); label-declaration frequency, not exposure; the underlying patch-test rates for this chemical are low (0-2.1%).
Skin allergy / Government agency
Alpha-isomethyl ionone ranks as an established human contact allergen in the EU opinion (category ++, 11-100 reported cases), but individual patch-test studies found positive rates of 0% to 2.1%, and the industry's own review lists four negative human induction tests.
Weak evidence: Low case counts and low prevalence; the industry review is the industry's position; the ++ rating partly reflects how often it has been tested.
Information, not medical advice. See also: myths we won’t tell you.