picture of baking soda on a table

Baking Soda and Underarms

Controlling body odor comes down to a science. So, let’s get the science-y basics out of the way first. We all have a layer of sweat and sebum that forms a coating on our skin known as the acid mantle. It may sound gross, but this coating protects our skin by preventing the growth of pathogenic bacteria and fungi. The average pH of the acid mantle is around 4.7, meaning it is not only slightly acidic but also healthy and considered a "natural" state (source).

You might have noticed that many natural deodorants contain sodium bicarbonate, or baking soda, with a pH of about 8 to 8.5 (alkaline). Deodorants containing baking soda rely on their odor-inhibiting properties to help control the bacteria growth in our underarms (source), which cause an odor when they break down sweat. Baking soda also lowers the pH levels of the environment, causing the bacteria, which usually feed off the acidic sweat's fatty acids, inability to function.

It's all in the formulation!

So why has baking soda been getting so much bad rep? Is it causing irritation and rashes? Well, we are back to science.

baking soda formula

Remember making the classic vinegar and baking soda volcano? A chemical reaction occurs when the alkaline baking soda deodorant is applied to our acidic underarms. Whoa! Does that mean everyone will get a bad reaction? Well, not really. It's all in the formulation! The possibility and severity of the rash or irritation depend on:

  1. The amount of baking soda in the product. More of it equals more possibility of a rash or irritation (source). You can check the amount by looking at the product ingredient list. The higher baking soda is listed, the higher the chances.
  2. The person’s acid mantle pH level can be affected by age, gender, race, medication, diet, or even that time of the month (yes, ladies, we have another thing to worry about).

Irritation vs. Allergic Reaction

It's important to note that many confuse this type of irritation with an allergic reaction (allergic contact dermatitis) or with what many know as detoxing. Underarm irritation and redness are not detoxing, and it's a myth that has been circulating for too long! Detox is an entirely different process, during which you may experience more pungent smelling body odor and sweat in excess. For more info on this and other reactions, please see Underarm Detox: Making a Clean Switch and Armpit Irritation and Rashes.

What can you do if you experience irritation or a rash in your underarms?

First, stop using any product that might be irritating and try to figure out the reason.

  • Is it the pH of the product? Are you using other alkaline products at the same time? Are you on your period? Did your diet recently change?
  • Are you allergic to an ingredient?
  • Or maybe it’s heat rash?
  • For more information, check out Armpit Irritation and Rashes.

Remember, figuring out the leading cause of discomfort can make the difference between the ability and inability to use this amazingly effective ingredient in your daily routine. 

Baking soda-free deodorant options

So what ingredient to use instead? Magnesium hydroxide is a gentler and more effective ingredient in natural deodorants. Like baking soda, magnesium hydroxide is also alkaline, with a pH of around 8. However, its slightly lower pH, closer to the skin's natural pH level, is a gentler ingredient and does not have the same potential for causing irritation as baking soda. Unlike baking soda, magnesium hydroxide is also insoluble in water, making it an effective moisture absorber that can help keep the underarm area dry and comfortable.

Additionally, magnesium hydroxide is gentle on the skin, making it an excellent alternative for people with sensitive skin who can't use baking soda-based deodorants.

Check our no baking soda options:

no baking soda deodorants


These statements are not intended to diagnose, treat, cure or prevent any disease. For any medical concern, you should consult with an appropriately-licensed physician or other health care worker. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. Full Medical Disclaimer.