Coumarin as a Fragrance Allergen and When to Declare It

Coumarin shows up in more formulas than people expect. It's the sweet, hay-like note behind a lot of vanilla and tonka accords, and it occurs naturally in tonka bean absolute, lavender, and a handful of other essential oils people reach for without thinking twice. It's also one of the named fragrance allergens Canada is moving onto the CNF and the label, which makes it a good ingredient to actually sit down and do the math on.

The two thresholds you're working against

Disclosure for fragrance allergens in Canada kicks in at different levels depending on how the product is used:

• Leave-on products: declare above 0.001%, which is 10 ppm
• Rinse-off products: declare above 0.01%, which is 100 ppm

That's a tenfold difference, and it exists because rinse-off products spend far less time in contact with skin. A body lotion sits on you all day. A shampoo is gone in under a minute. The threshold reflects that difference in exposure.

Doing the math when coumarin comes from an essential oil

Here's where makers get tripped up. Coumarin rarely gets added as a pure ingredient in a small-batch formula. It usually rides in on an essential oil or absolute. Say you're using tonka bean absolute at 2% in a leave-on body butter, and the supplier's documentation lists coumarin content in that absolute at roughly 3% of the absolute itself.

The concentration in your finished product is:

2% (absolute in formula) × 3% (coumarin in absolute) = 0.06% coumarin in the finished product

That's 600 ppm, which clears the 10 ppm leave-on threshold by a wide margin. It needs to be declared.

Now compare a rinse-off case. A shampoo bar uses the same tonka absolute at 0.5%:

0.5% × 3% = 0.015% coumarin, or 150 ppm

Still above the 100 ppm rinse-off threshold, so it still needs declaring, just barely. Drop the absolute to 0.2% in that same rinse-off formula and you land at 60 ppm, under the threshold, and no declaration is required for coumarin from that source.

This is exactly why "it's just a natural essential oil" isn't a safe assumption to lean on. The allergen content of a botanical isn't fixed, it varies by supplier and batch, and your only real source of truth is the supplier's documentation or a certificate of analysis.

A quick reference table

Allergen	Common natural source	Leave-on threshold	Rinse-off threshold
Coumarin	Tonka bean absolute, lavender	0.001% (10 ppm)	0.01% (100 ppm)
Linalool	Lavender, bergamot, many florals	0.001% (10 ppm)	0.01% (100 ppm)
Limonene	Citrus oils	0.001% (10 ppm)	0.01% (100 ppm)
Eugenol	Clove, cinnamon	0.001% (10 ppm)	0.01% (100 ppm)

The thresholds are the same across List 1 allergens. What changes is which allergens are present in your specific fragrance or essential oil blend, and at what concentration.

The two-list timeline matters for planning

Canada is phasing this in over two dates. List 1, the original fragrance allergen set that includes coumarin, becomes mandatory on both the CNF and the label on April 12, 2026. List 2, an expanded set aligned with international lists, follows on August 1, 2026. If you're reformulating or relabeling right now, it's worth pulling the full allergen profile from your fragrance or essential oil supplier once rather than twice, since you'll need the List 2 data soon after the List 1 deadline anyway.

Getting the supplier data you actually need

You can't calculate any of this without a document that states the coumarin percentage in whatever raw material you're using. If your supplier hasn't given you that, ask specifically for the allergen breakdown, not just a generic safety data sheet. Section 3 of an SDS lists composition, but it doesn't always break out trace allergen constituents the way a dedicated allergen declaration does.

If you're tracking several fragrance oils across a product line, this kind of multiplication needs to happen for every allergen in every blend, which adds up fast by hand. Cosmetic Comply carries these percentages through automatically when it expands a supplier blend, so the coumarin (or linalool, or geraniol) contribution from each fragrance component shows up against the actual threshold rather than sitting buried in a spreadsheet somewhere. Either way, checking your specific formula's numbers against Health Canada's current allergen list before your filing date is the safest habit to build now.