Yellow Pit Stains Aren’t Your Sweat — Learn the Science Behind All the Chemical Reactions Happening

Photo Credit: iStock

White T-shirts are cute — until the inevitable yellow pit stains. The stains can be super annoying to get out, and many people think they’re caused solely by sweat. So, antiperspirant or deodorant should prevent them, right? Wrong.

On the contrary, yellow pit stains are actually caused by antiperspirant.  They develop from a chemical reaction among the proteins in sweat, the cotton in T-shirts, and the aluminum salts in antiperspirant.

Photo Credit: iStock

Aluminum is the key active ingredient in antiperspirant, and it’s what differentiates antiperspirants from plain deodorants. The ingredient has become controversial in recent decades due to a fear that it is linked to breast cancer (though there’s actually not a clear link). Some health advocates also say that it’s just healthier to let yourself sweat.

Well, apparently there is another reason to avoid aluminum — it is the cause of those pesky yellow pit stains. At the very least, adding more antiperspirant is definitely not going to solve the yellow stain problem.

Photo Credit: iStock

But even before aluminum-based antiperspirant, sweat stains came in a wide range of colors depending on what products people used for deodorant. Around the turn of the 20th century, a product called Odorono tended to result in red underarm stains. Clothing artifacts from history show sweat stains that are yellow, orange, red, brown or even green.

Luckily, there are other

to prevent yellow pit stains without switching your deodorant. You can pre-treat your new, unyellowed T-shirts with an enzymatic laundry spray right after you wear them, or add a bit of lemon juice to your load of whites (but only whites!).