Eugenol: The Clove Allergen and When to List It

Clove oil smells warm and a little medicinal, which is exactly eugenol doing its thing. It is also one of the fragrance allergens that dermatology literature flags more consistently than most of its neighbors on the standard allergen list, which makes it worth understanding on its own rather than lumping it in with the rest.

Where eugenol actually comes from

Eugenol is not something formulators add as an isolated allergen concern first, it is something they inherit by choosing certain essential oils. It occurs naturally, often at meaningful concentrations, in:

• Clove oil (Syzygium aromaticum), where it is frequently the dominant component
• Cinnamon leaf oil and cinnamon bark oil
• Basil oil
• Bay leaf oil
• Smaller amounts in rose and other florals

If your formula includes any of these essential oils for scent or for their perceived skin benefits, eugenol is very likely coming along with them whether or not you intentionally added it.

Why it gets more attention than some other allergens

Eugenol sits alongside Limonene, Linalool, Citronellol, Geraniol, and Coumarin as one of the more commonly discussed fragrance allergens, but it has a stronger and more frequently documented sensitization profile in patch-test literature than several of the others on that list. That does not mean it is prohibited or even discouraged. It means the disclosure requirement exists specifically because enough people react to it that consumers deserve the chance to see it coming.

The disclosure thresholds

In Canada, the applicable thresholds are the same regardless of which specific allergen you are looking at: above 0.001% (10 ppm) in leave-on products, and above 0.01% (100 ppm) in rinse-off products. Where eugenol becomes a practical issue is that clove and cinnamon oils carry it at high enough native concentrations that even a modest dose of the essential oil in your formula can push you over either threshold quickly.

A rough way to think about it: if clove bud oil is roughly 70 to 90 percent eugenol by composition, and you are using clove oil at even half a percent in a leave-on lotion, you are almost certainly well above the 10 ppm leave-on trigger. This is exactly the kind of math that is easy to skip and easy to get wrong by hand, since it requires knowing both the essential oil's actual eugenol content and doing the percentage-of-percentage multiplication correctly.

Timeline to keep on your radar

Fragrance allergen disclosure in Canada is shifting from optional to mandatory on a defined timeline. List 1, the original fragrance allergen set that includes eugenol, becomes mandatory on both the Cosmetic Notification Form and the product label on April 12, 2026. List 2, an expanded set aligned with international lists, follows on August 1, 2026. If you are formulating with clove, cinnamon, or basil oil right now, building the disclosure habit ahead of that date saves you a scramble later.

A quick reference

Essential oil	Approximate eugenol share	Common use
Clove bud oil	High, often majority component	Scent, warming sensory note
Cinnamon leaf oil	Moderate to high	Scent, spice-forward blends
Basil oil	Lower but present	Herbal fragrance notes
Bay leaf oil	Moderate	Scent blends, some traditional formulations

Treat the percentages as general guidance rather than a number to plug directly into a filing. Actual eugenol content varies by supplier, harvest, and extraction method, so pull it from your specific essential oil's certificate of analysis when you need a real figure.

What to actually do about it

Get the certificate of analysis for any clove, cinnamon, or basil oil you use, check its documented eugenol percentage, and run that against your use level in the finished formula. If you land above the relevant threshold, eugenol needs to be named specifically rather than folded into a generic "fragrance" or "parfum" listing.

This is one of the calculations Cosmetic Comply handles automatically, tracing eugenol and the other named allergens through your essential oils and blends to the actual finished-product percentage, so you are not doing the certificate-of-analysis math by hand for every batch.