Here’s Why You Get Pit Stains (And How to Get Rid of Them)

Your sweat isn’t the main culprit after all.


“Why do I get pit stains?” you ask? Here’s the super simple answer: Aluminium. This is the active ingredient in most antiperspirants, and it chemically reacts with the protein in your sweat to cause underarm yellowing. Cotton shirts are also made up of protein, which only adds fuel to the fire and explains why pit stains appear on white undershirts and dress shirts after just a few sweats. There are, however, simple ways to both remove and prevent pit stains, which we’ve listed below.

Removing Pit Stains
You asked us, “Why do I get pit stains?” which probably means two things: First, you already have pit stains, and second, you want them gone. But before we get into the various treatments for removing pit stains, know that chlorine bleach will only serve to render the discolouration more yellow: That’s because chlorine bleach, similar to aluminium, reacts to proteins by forming a yellowing concoction.

With that out of the way, here are a few simple (and effective) ways to remove pit stains:

  • Oxygenated Bleach: Oxygenated bleaches have a different chemical structure to chlorine bleaches and are highly effective at removing pit stains. If the stain is new, simply sprinkling some oxygenated bleach in the wash (hot water is best here) should remove it. Yellow stains that have set in because you dried the garment before removing the stains, however, require a bit more work. Here’s what to do to remove pit stains that have settled in for the long haul: Fill up your (clean) sink with hot water, and stir in one scoop of  good oxygenated bleach until the powder has dissolved. Add your stained garments and let them soak for 15-30 minutes. Then, rub the stained fabric against itself while its submerged in the cleaning solution. Lastly, launder the garment as usual.
  • White Vinegar: If you’re looking for something a bit less commercial, we recommend turning the shirt inside out and dousing the underarm area with white vinegar. Let the area soak for up to an hour, then use an old toothbrush to lightly brush and rub the vinegar into the stain. Lastly, launder the garment on the “normal” cycle using warm water.
  • Hydrogen Peroxide: One of the simplest ways to remove pit stains is to fill a small bowl with hydrogen peroxide and soak the stained part of the shirt for 30 minutes before laundering as usual. This method, however, should be reserved for lighter stains, since tougher stains require scrubbing.

Preventing Pit Stains
Now that you know how to get rid of pit stains, here’s how to keep them to a minimum without ditching antiperspirants—the main culprit—altogether (note: Pit stains are somewhat inevitable if you use an aluminium-based antiperspirant, so while these tips may help reduce the appearance of pit stains, don’t expect them to prevent stains altogether):

  • Dress to Reduce Sweating: Wear loose clothing made of natural fibres—like cotton, linen and wool—which will keep you cool and allow your sweat to evaporate, rather than soak into your clothes.
  • Apply Antiperspirant Correctly: Make sure your antiperspirant is dry before putting a shirt on to prevent cross-contamination.
  • Go Easy on the Product: Don’t apply too much antiperspirant, as this can lead to buildup, which can cause heavier and darker sweat stains.

If these tips don’t help, there are many aluminium-free antiperspirants that won’t cause pit stains. In most cases, these antiperspirants replace aluminium with charcoal, which can absorb 1000 times its weight in moisture. Be warned, though: While charcoal does absorb sweat, it doesn’t stop you from sweating altogether the way aluminium does, so that’s something to keep in mind when using aluminium-free antiperspirants.

There you have it: Next time someone asks you, “Why do I get pit stains?” not only will you be able to tell them it’s actually their antiperspirant that’s to blame, you’ll also be able to show them how to remove pesky pit stains, and how to keep them from showing back up. You useful thing, you.