Dehydroacetic Acid and Benzyl Alcohol: A Popular Preservative Duo

If you've bought a preservative under a trade name like Geogard 221 or something similar from a different supplier, you've probably noticed the certificate of analysis lists two separate compounds instead of one. That's normal. Most of these commercial blends are built around dehydroacetic acid and benzyl alcohol working together, and neither the trade name nor the blend as a whole is what goes on your filing. The two components are.

What's actually in the bottle

Dehydroacetic acid and benzyl alcohol are usually sold as a pre-mixed liquid, often at a ratio that puts benzyl alcohol as the larger fraction. The blend works because the two compounds cover different territory: dehydroacetic acid is particularly useful against mold and yeast, while benzyl alcohol adds broader antimicrobial action and also functions as a mild solvent.

INCI name	Approximate CAS number	Typical function
Benzyl Alcohol	100-51-6	Preservative, solvent, fragrance ingredient
Dehydroacetic Acid	520-45-6	Preservative, antifungal

Always confirm the CAS number against your specific supplier's documentation. Some suppliers list the sodium salt form of dehydroacetic acid instead of the free acid, which carries a different CAS number, so don't assume the number above applies without checking your actual certificate of analysis.

Why you can't just list the trade name

Trade names never appear on a Cosmetic Notification Form. Health Canada's system is built around INCI names because that's the naming convention that lets a reviewer, or anyone else, actually identify what's in the product regardless of which supplier sold it to you or what they branded it. If your supplier's spec sheet says "Preservative X" and doesn't break down the INCI names and percentages, ask for a full certificate of analysis before you use it. You need that document anyway for your own records.

Doing the math on concentration

This is where people get tripped up. Say your supplier's blend is 70% benzyl alcohol and 30% dehydroacetic acid, and you're using the blend at 0.8% of your total formula. You don't list "0.8% preservative blend." You calculate each component's real concentration in the finished product:

• Benzyl Alcohol: 0.8% x 0.70 = 0.56%
• Dehydroacetic Acid: 0.8% x 0.30 = 0.24%

Those are the two numbers that go on your ingredient list, each under its own INCI name, not the blend percentage and not the trade name. If you're also using a separate fragrance oil that itself contains benzyl alcohol, and many do since it's naturally present in some essential oils, you need to add both sources together before you list the final concentration. That's a common miss: two different raw materials contributing to the same INCI line, and each one only counted separately instead of summed.

Where this preservative shows up

You'll see this pairing most often in:

• Leave-on facial and body lotions
• Rinse-off cleansers and shampoos where a lighter preservative load is wanted
• Natural or "clean" positioned product lines, since both compounds have a longer history of use and read well on a label to that audience

Benzyl alcohol also has a use as a fragrance ingredient in its own right, so if your formula already contains it as a scent component from an essential oil and you're adding this preservative blend on top, both contributions need to be tracked and summed before you file.

A quick sanity check before you submit

1. Get the actual INCI breakdown and percentage ratio from your supplier's certificate of analysis, not the trade name sheet.
2. Multiply the blend's use level in your formula by each component's percentage in the blend.
3. Check whether either INCI name already appears elsewhere in your formula from a different raw material, and sum if so.
4. Confirm the CAS numbers you're recording match your supplier's actual product, since salt forms and free-acid forms differ.

This kind of math is exactly the tedious part of a filing that's easy to get slightly wrong, especially once you're juggling four or five raw materials that each contribute to the same handful of INCI names. Cosmetic Comply handles that expansion automatically. Feed it your formula and supplier blend ratios, and it maps everything to INCI names and CAS numbers, sums duplicate contributions, and screens the result before a real reviewer signs off and it goes out as a notification.