Xanthan Gum: Notifying a Natural Thickener and Stabilizer

Xanthan gum shows up in everything from salad dressing to shampoo, and the reason it's such a workhorse ingredient is the same in both: a tiny amount creates a lot of viscosity, and it does it without much sensitivity to temperature or pH swings. If you're formulating a lotion, gel, or liquid soap and reaching for a thickener, xanthan is probably the first one you'll try, so it's worth knowing exactly what you're filing when it's on your ingredient list.

What it is

Xanthan gum is a polysaccharide produced by fermenting sugar with a bacterium, Xanthomonas campestris. It's classified as natural in most clean-label senses, since it comes from a fermentation process rather than petrochemical synthesis, though "natural" isn't itself a regulated cosmetic term you can lean on without support.

INCI name: Xanthan Gum CAS number: 11138-66-2 Typical function: viscosity controller, thickener, stabilizer

Why it works so well

Xanthan gum forms a weak, shear-thinning gel network in water. That means your product feels thick sitting still in the jar but flows more easily under the shear of rubbing it between your hands, which is part of why it's so popular in leave-on lotions and creams where texture matters to the user. It also helps suspend particulates, like exfoliating beads or mica, that would otherwise settle at the bottom of a bottle.

Typical use levels

Most formulators use xanthan gum somewhere in the range of 0.1% to 1.0% of the total formula, depending on the target viscosity. Small changes make a big difference here. Going from 0.2% to 0.4% can take a runny lotion to something closer to a pudding, so it's usually added slowly and tested incrementally rather than dosed all at once.

Product type	Typical xanthan gum range
Thin lotions, sprays	0.1-0.2%
Standard creams	0.2-0.5%
Gels, thick serums	0.5-1.0%
Suspending particulates in a liquid	0.1-0.3%

These are general starting points, not fixed rules. Every base formula behaves differently, so bench testing your own version is still the only reliable way to land on a number.

Filing notes

Xanthan gum is filed by its INCI name and the concentration or concentration range you use. It isn't one of the more complicated entries on a notification since it's a single well-known substance with one CAS number and no supplier blend to unpack, unlike some thickening systems that combine xanthan with other gums or polymers in a pre-mixed blend.

If you are using a pre-blended thickening system that includes xanthan gum alongside other polymers, treat it the way you would any supplier blend: check the SDS or the supplier's technical data sheet for the actual percentage of xanthan within the blend, then multiply that by your use level of the blend to get the true finished-product concentration. Don't file the blend's trade name as if it were a single ingredient.

A couple of practical formulation quirks

Xanthan gum can be tricky to disperse without clumping ("fisheyes"), especially if it's added directly to water without pre-mixing with glycerin or another humectant first, or without slow addition under high shear. This is a formulation issue rather than a regulatory one, but it's the most common complaint from makers switching to xanthan for the first time, so it's worth mentioning if you're writing your own batch instructions.

It also isn't flagged on prohibited or restricted ingredient lists in the markets Cosmetic Comply currently supports, though as always with any restricted list, status can shift over time and it's worth checking the current version rather than relying on last year's information.

Keeping the filing simple

Because xanthan gum is such a common, well-documented ingredient, it's one of the easier lines on a Cosmetic Notification Form. The harder work usually lives elsewhere in your formula, in fragrance blends or actives with tighter limits. Cosmetic Comply matches ingredients like xanthan gum to their INCI and CAS automatically as part of screening your whole formula, so the easy entries don't eat up time that's better spent double-checking the trickier ones.