# Toxic levels of baking soda

What is the amount of baking soda that would be considered toxic for skin? I ask because there is a lot of misinformation online about using baking soda as a "natural" underarm deodorant, and how it is or is not harmful to use as such. Please clarify.

Thank you for your time in advance.

• I wouldn't recommend labelling it "misinformation" until you actually know it to be false. – SendersReagent Mar 25 '16 at 19:34
• Here is a material safety data sheet (MSDS) for sodium bicarbonate. sciencelab.com/msds.php?msdsId=9927258 It is about as harmless as a chemical can be. // I'm unsure about how it would be used as a deodorant. The grain size of typical grocery store purchased baking soda would be abrasive to the skin. // I don't know if you're reacting to the fact that baking soda is a "chemical" or not. Water is a chemical, and oxygen in the air is a chemical. It is true that a strawberry isn't "a" chemical, it is made up of thousands of chemicals. – MaxW Mar 25 '16 at 20:15
• I used soda bicarbonate as an underarm deodorant for about three years. Not every day but fairly consistently. At a certain stage I noticed aching shoulders, and I stopped it's use. I used a brand that had "aluminium free" printed on the label, which suggests some producers mix aluminium into their soda bicarbonate. Poor soda bicarbonate can't fight in the heavy-weight ring without some additives. When we talk about soda bicarbonate, what other additives are we talking about and blaming on sweet little soda. Without a full spectrum microscope what do I know? – Alan Keating Jun 3 '17 at 16:43

Baking soda is sodium hydrogencarbonate, $\ce{NaHCO3}$, also known as sodium bicarbonate.
In water, $\ce{NaHCO3}$ is weakly alkaline. I do not know whether it might cause skin irritations, particularly in more sensitive regions, such as armpits.