Ethylhexylglycerin

Overview

Ethylhexylglycerin (CAS 70445-33-9) is a glyceryl ether — structurally, a glycerin molecule with an ethylhexyl chain attached. That dual nature gives it some useful tricks: it boosts the antimicrobial activity of other preservatives, provides mild deodorant properties, and conditions the skin, all in one ingredient.

It is a clear, slightly viscous liquid with a faint rose-like scent. It mixes well into oils and oil-containing formulas but has limited solubility in pure water. In water-only systems, you will need a surfactant or solubiliser to incorporate it properly.

To be very clear: ethylhexylglycerin is not a standalone preservative. It does not have enough antimicrobial power on its own to protect a water-containing product. What it does, and does well, is make your actual preservative system work harder. It is especially effective at boosting weak organic acid preservatives and is often paired with phenylethyl alcohol (the combination shows up in many commercial preservative blends).

What it does in a formula

Ethylhexylglycerin works by disrupting the cell membranes of bacteria and other microorganisms, making them more vulnerable to your primary preservative. Think of it as softening the enemy’s armor so your main weapon hits harder. This synergistic effect means you can often use lower concentrations of your primary preservative while maintaining the same level of protection — which is a win for skin tolerance.

The deodorising function comes from the same antibacterial mechanism. By reducing odour-causing bacteria on the skin surface, it helps control body odour in deodorant and body care formulas. The skin-conditioning aspect is a bonus — the glycerin backbone provides mild humectant properties, so it does not feel harsh or drying.

It works across a wide pH range (effective up to pH 12), which makes it versatile for formulas at various pH levels. Most preservatives have a narrow optimal pH window; ethylhexylglycerin does not share that limitation.

How to use

Add to the oil phase or during cool-down (below 80 C maximum processing temperature). It blends easily into oil phases and emulsions. For water-based formulas without an oil phase, you will need to pre-dissolve it in a small amount of solubiliser or surfactant before adding it to the water phase.

Usage rates by product type:

• Emulsions (creams, lotions): 0.5-1% (as preservative booster)
• Serums and essences: 0.5-0.8%
• Surfactant-based products (shampoo, body wash): 0.5-1%
• Deodorants: 0.5-1%
• Anhydrous products: 0.3-0.5% (mostly for deodorising benefit; preservation is less critical without water)

Best for / Worst for

Best for: boosting organic acid preservative systems, emulsions and creams that need extra microbial protection, natural deodorant formulas, formulas where you want to minimise the concentration of stronger preservatives, products across a wide pH range.

Worst for: water-only formulas without a surfactant or solubiliser (it will not disperse properly), use as a sole preservative (it cannot protect a product alone), formulas processed above 80 C for extended periods.

Common pitfalls

Treating it as a standalone preservative. This is the most common mistake. Ethylhexylglycerin alone will not pass a preservative efficacy test (challenge test). You always need it paired with a primary preservative system — phenylethyl alcohol, potassium sorbate, sodium benzoate, or similar.

Adding it to hot water phases directly. While it tolerates up to 80 C, it is oil-soluble and will not disperse in a hot water phase without help. Either add it to your oil phase before emulsification, or dissolve it in a compatible solubiliser first.

Exceeding 1%. At concentrations above 1%, some users report mild skin irritation, especially on sensitive facial skin. Stay within the recommended 0.5-1% range.

Forgetting it in your preservative efficacy testing. If you are sending products for challenge testing, your booster is part of the system. Test the complete formula, not just the primary preservative in isolation.

Substitutes

• Caprylyl glycol — another glyceryl ether with similar preservative-boosting and skin-conditioning properties. Slightly better water solubility.
• Pentylene glycol — a 1,2-diol with antimicrobial boosting and humectant properties. Water-soluble, so easier to use in water-based formulas.
• Propanediol (and) caprylyl glycol — a pre-blended booster system that is easier to formulate with in water phases.
• Decylene glycol — stronger antimicrobial boosting than ethylhexylglycerin, but also more irritating at higher concentrations. Use at lower percentages.