Magnesium hydroxide vs. baking soda in natural deodorant

Short answer: both are alkaline minerals used to control underarm odor. Baking soda (sodium bicarbonate) is more alkaline and more soluble, which makes it potent and also makes it the usual suspect when a natural deodorant starts stinging. Magnesium hydroxide is far less soluble and sits closer to skin-friendly territory, which is why we chose it.

Side by side

• Alkalinity: baking soda is noticeably more alkaline than magnesium hydroxide in a wet underarm. Skin's own surface is slightly acidic.
• Solubility: baking soda dissolves readily in sweat, so it acts fast and reaches skin fully. Magnesium hydroxide is poorly soluble, so it works more gradually and gently.
• Texture: soda can feel gritty if not fully incorporated; magnesium hydroxide is a fine, soft powder.
• Tolerance on shaved skin: this is the deciding factor for most people who switch.
• Cost: soda is cheaper, which is part of why it dominates the category.

Why we don't split the difference

Some brands use a small amount of baking soda plus magnesium hydroxide to get speed and gentleness at once. It's a reasonable formulation choice. We didn't take it, because the whole point of our formula is a four-ingredient jar you can hand to someone with reactive underarms without a caveat.

What it feels like in practice

Magnesium hydroxide doesn't announce itself. There's no tingle, no cooling, no burn. Combined with a tallow and coconut oil base, the application feels like putting on a moisturizer rather than a deodorant — which is exactly the experience we were after.

Keep reading

Go deeper on the ingredient in what magnesium hydroxide does in deodorant, see the whole formula on our ingredients page, or read the complete guide to tallow deodorant.