Magnesium has become a buzzword on deodorant labels, usually with zero explanation of why it's there. Here's the short version: it isn't the primary thing stopping your odor, but it does more than the label lets on.

What magnesium actually does

In a well-built natural deodorant, magnesium hydroxide is a supporting active. It's a mild mineral that gently neutralizes the acidic odor compounds bacteria produce, right as they form, without the harshness of baking soda. That's real odor work, a steady second layer, but it's support, not the engine. The primary source-level active is zinc.

Why the distinction matters

Plenty of "magnesium deodorants" lean on the word as if magnesium were doing all the heavy lifting. In the best formulas it isn't working alone: the source-level work, acting on the bacteria and molecules that create smell, comes from the zinc-based BioShield™ system, with magnesium neutralizing acidic byproducts alongside it. Magnesium plus zinc is stronger than magnesium leaning on the label.

Where Zaffré uses it

Magnesium is the support system in two of our formulas. Core and Max pair the zinc with magnesium (Core actually carries a little more of it). Sensitive is magnesium-free and instead works with your skin's own acidity, the gentlest path, which is why it suits reactive skin. Same zinc core eliminating odor at the source; magnesium is the supporting layer, present in Core and Max, absent in Sensitive.

So if you're shopping "magnesium deodorant," the better question isn't whether it contains magnesium, it's what's actually stopping the odor underneath, and whether the magnesium is doing real work or just decorating the label.

Related: magnesium vs zinc, and the buyer's guide.