The Science Behind Pit Stains & How to Stop Them

Are you bothered by pit stains? We’ve all been there. It’s embarrassing to flash yellow armpit stains when raise your hand or lift your arms.

And for those who struggle with armpit stains, laundry day is a burden. Pit stains are difficult to clean, or impossible to get out altogether. It’s painful (and wasteful) to throw away a shirt that's still in good shape.

But, pit stains don’t have to plague your day-to-day life! Read on to learn the science behind pit stains and the best ways to prevent and remove yellow armpit stains from clothing.

In this guide, we'll cover:

  • What Are Pit Stains? How Armpit Stains Form
  • How to Stop Pit Stains and Prevent Them
  • How to Get Rid of Armpit Stains From Shirts

What Are Pit Stains? How Armpit Stains Form

What causes yellow armpit stains? Newsflash: It’s not just sweat.

Here’s the basic science: pit stains occur when the proteins in your sweat react with the aluminum and other chemicals in your antiperspirant.

Apocrine sweat glands, which are the glands found in your underarms, produce a different type of sweat compared to eccrine sweat glands (found elsewhere on your body). Unlike eccrine sweat, apocrine sweat is full of fats and proteins, which contribute to stains and odor.

Aluminum is the active ingredient in most over-the-counter and prescription antiperspirants, while your sweat consists of water, ammonia, urea, salts and sugar. Sweat, on its own, is actually odorless and colorless.

So, as the composition of your armpit sweat mixes with the ingredients of your antiperspirant, the result is a pesky yellow pit stain that’s tough to get out. And if you regularly wear white undershirts, you’ll notice that the stain is much more apparent.

Learn more on our Sweat Stains resource page.

How to Stop Pit Stains

So what’s the best way to stop pit stains?

By understanding the science behind pit stains and knowing how they form, you can attack the problem at the source.

Here are our top three tips to stop pit stains and avoid them for good:

  1. Change your antiperspirant or deodorant routine
  2. Wear a sweat proof undershirt for protection
  3. Take proper care of your clothing

1. Change Your Antiperspirant or Deodorant Routine

You may be applying antiperspirant incorrectly, or using a product that isn't suitable for your needs. Try these techniques to modify your antiperspirant or deodorant routine:

  • Don't over-apply the product. A few swipes is all you need! Over-application of deodorant or antiperspirant will leave residue on your clothing that can make stains worse.
  • Switch from using antiperspirant to deodorant. The main ingredient in most antiperspirants, aluminum, is the culprit of yellow armpit stains. If you don't sweat as heavily, consider using deodorant instead of antiperspirant.
  • Apply antiperspirant or deodorant before bed. Allow time for the product to set in and do its job. This improves the effectiveness of your deodorant or antiperspirant, which can help you sweat less and reduce armpit stains.

2. Wear a Sweat Proof Undershirt for Protection

A sweat proof undershirt is the easiest, most hassle-free way to stop pit stains from ruining through your clothes.

Recurring pit stains and constant laundering or stain removal can drastically reduce the lifespan of your shirt. Wearing a sweat proof undershirt protects your outer layers of clothing, meaning you won’t have to launder as often or use chemical-based products to remove stains aggressively. Plus, you’ll save all the money that you'd normally spend on replacing your shirts every few months.

For the best sweat proof undershirt, look no further than the Thompson Tee for men and women. Sweat proof Thompson Tees feature patented Hydro-Shield technology that can withstand and block 100% of armpit sweat and odor from reaching your outer layers. Absolutely no more pit stains — guaranteed or your money back.

Ready to eliminate pit stains for good and regain your confidence? Try a Thompson Tee risk-free today!

For more tips on how to prevent pit stains, check out our blog.

3. Take Proper Care of Your Clothing

By following proper laundry protocol, you can reduce the occurrence of pit stains or make them much easier to remove.

If you’re prone to pitting out, follow our suggestions for taking good care of your shirts and preventing pit stains:

  • Don’t wait too long to wash sweaty shirts. The stain will have time to set in permanently. Plus, damp sweat is a breeding ground for bacteria.
  • Pre-treat severe stains before tossing the shirt in the wash. Products like OxiClean can be effective, but only when used correctly. You can also try other DIY methods, like aspirin or a vinegar and baking soda combination.
  • Skip the bleach. Although bleach has whitening effects, it actually worsens pit stains on fabrics like spandex, wool, silk or leather. The same goes for drying your clothes out in the sun.
  • Dry on low heat or air-dry if possible. Heat can make stains more difficult to remove if they’ve already set in.
  • Take your shirt to the dry cleaner if necessary. Let the cleaners know to pay special attention to any severe stains.

How to Get Rid of Armpit Stains From Shirts

To remove yellow armpit stains from clothing that seem almost impossible to get out, there are a few solutions you can try. Here are our top tactics:

  1. Vinegar, baking soda and hydrogen peroxide: Mix one cup white vinegar, half-cup baking soda, one tablespoon salt and one tablespoon hydrogen peroxide into a paste. Use a brush to scrub the paste into the stain and let it sit for 15 minutes, then machine wash per the shirt's instructions.
  2. Use a product like OxiClean or Raise Stain Remover. These store-bought products are effective at removing stubborn armpit stains. Follow the instructions on the packaging for best results.

For even more tips and tricks to get rid of sweat stains from shirts, check out our blog.

What other tips do you have for stopping armpit stains and keeping underarm sweat away? Let us know!