The essentials
Methyleugenol, chemically 4-allyl-1,2-dimethoxybenzene, is a phenylpropanoid that occurs naturally in basil, tarragon, clove, nutmeg, lemon balm, and several other essential oils. It is not a synthetic added to formulas by perfumers but an inherent component of the natural raw materials. The International Agency for Research on Cancer (IARC) classified it as Group 2B, possibly carcinogenic to humans, in 2013 based on animal study evidence of liver tumors at high oral exposure (IARC Monographs, Volume 101, 2013).
The IFRA Standard restricts methyleugenol to a maximum of 0.01% in leave-on cosmetic products such as eau de parfum and eau de toilette, with lower limits for products intended for sensitive skin areas. The restriction is enforced through the IFRA Code of Practice and aligns with EU Cosmetics Regulation Annex II prohibitions and the Scientific Committee on Consumer Safety opinions issued from 2002 onward (IFRA Standards Library, methyleugenol entry, accessed 2026-05-29).
For perfumers, the practical constraint is on the natural oils that contain methyleugenol at significant levels. Basil oil typically contains 1 to 60% methyleugenol depending on chemotype, clove bud oil 0.1 to 0.5%, and tarragon oil up to 5%. To stay within the 0.01% finished-product limit, the natural oil concentration in the formula must be kept very low, or the natural must be replaced by a methyleugenol-free distilled fraction or by synthetic reconstructions of the desired olfactory profile.
What methyleugenol actually is
Methyleugenol is a substituted phenylpropene with a sweet, slightly clove-like, anise-warm odor. It is structurally close to eugenol, the dominant odorant of clove, with an additional methyl group on the oxygen. The molecule is biosynthesized by many plant species in the Lamiaceae (mint family) and Lauraceae (laurel family) as a secondary metabolite, often as a defense or signaling compound.
Industrially, methyleugenol is not produced for use as a perfumery raw material. Its presence in finished perfumes is always indirect, arising from the natural oils in which it occurs. This indirect presence is what makes the restriction operationally complex: a formula does not contain methyleugenol because the perfumer added it, but because a basil or clove note carries it.
The carcinogenicity findings
The IARC classification rests on rodent carcinogenicity studies conducted by the US National Toxicology Program (NTP) in the early 2000s. Long-term oral administration produced increased incidences of liver tumors in rats and mice at doses well above any plausible perfumery exposure. The molecule was further characterized as genotoxic in some in vitro assays, supporting the 2B classification.
The Scientific Committee on Consumer Safety opinion of 2002 reviewed the dossier and recommended restrictive limits for cosmetic applications, prompting the IFRA Standard. The same body has periodically reaffirmed the position, most recently in opinions accompanying the 2023 seventh amendment to Annex III. The regulatory consensus is that methyleugenol exposure should be kept as low as reasonably practicable in leave-on cosmetics (SCCS Opinion on methyleugenol, 2002, reaffirmed in subsequent reviews).
The IFRA Standard and EU regulatory framework
The IFRA Standard sets the maximum concentration of methyleugenol in the finished consumer product at 0.01% (100 ppm) for fine fragrance in Category 4 (leave-on, hydroalcoholic perfumes). Stricter limits apply to product categories with direct mucosal contact or for products targeting children. The Code requires fragrance suppliers to certify the methyleugenol content of each delivered concentrate.
The EU Cosmetics Regulation 1223/2009 Annex II lists methyleugenol as a prohibited substance for direct addition, with quantitative thresholds set in Annex III for indirect presence from natural sources. The two frameworks reinforce each other: IFRA defines the perfumery industry standard, and EU law gives it legal force across all cosmetics placed on the EU market.
Naturals affected by the restriction
The most affected naturals are the ones with high methyleugenol content. Different basil chemotypes range from 1 to 60% methyleugenol, with the linalool chemotype lowest and the methylchavicol-rich chemotype highest. Tarragon (estragon) oil contains up to 5%. Clove bud oil contains 0.1 to 0.5%, principally as a minor component alongside the dominant eugenol. Nutmeg, mace, and pimento oils also contain measurable levels.
Suppliers such as Robertet, Mane, Symrise, and Givaudan now offer methyleugenol-reduced or methyleugenol-free fractions of these naturals, obtained through molecular distillation or selective adsorption. The reduced fractions present a slightly different olfactive profile than the crude oil, but they allow perfumers to maintain the natural character of basil, tarragon, or clove within regulatory limits.
Documented reformulation cases
Femme de Rochas, originally composed by Edmond Roudnitska in 1944, is sometimes cited as a case affected by allergen and animalic restrictions. The 1989 reformulation by Olivier Cresp added the now-distinctive cumin facet, after which subsequent regulatory tightening forced further adjustments. Reading the layered history of Femme requires distinguishing between the Roudnitska original, the Cresp 1989 version, and the post-2000 versions adjusted for IFRA compliance.
Spice-forward chypres and orientals from heritage houses have similarly required staged reformulations. The shift toward methyleugenol-reduced naturals or synthetic spice reconstructions is a common factor across the heritage classics, with each house managing the transition according to its own technical and commercial priorities.
What niche houses do today
Contemporary niche perfumery has built its spice palette within the current restrictions. Houses such as Frederic Malle, Andy Tauer, Aedes de Venustas, and Naomi Goodsir use methyleugenol-reduced basil and clove fractions, or synthetic reconstructions, to deliver the spicy character without exceeding limits. The result is often a cleaner, more focused spice expression than vintage compositions delivered.
For consumers, the restriction is largely invisible. The methyleugenol limit shapes what perfumers can do at the formula level, but the finished perfume reads as a normal spicy composition. The regulatory architecture exists precisely to allow continued use of these familiar naturals within a safety envelope that addresses the carcinogenicity findings while preserving the perfumer's olfactory toolkit (IFRA Standards Library, accessed 2026-05-29).
Sources
- IARC, Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 101, methyleugenol classification as Group 2B, 2013.
- IFRA Standards Library, methyleugenol entry, current amendment to the Code of Practice. Accessed 2026-05-29.
- European Commission, Regulation (EC) 1223/2009, Annex II and Annex III provisions on methyleugenol. Accessed 2026-05-29.
- Scientific Committee on Consumer Safety, opinion on methyleugenol, 2002 and subsequent reviews. Accessed 2026-05-29.