Written by Lisa Truesdale. Reviewed by cleaning expert Sean Busch.

The bad news is, your favorite shirts are always stained under the arms, making them difficult to clean, and it’s also pretty embarrassing.

But there’s good news, too: Not all pit stains are created equally. Once you know the difference, you’ll be able to get those stains out and start wearing some of your favorite shirts again in no time.

What Causes Yellow Armpit Stains?

First, a quick biology lesson. Our bodies actually have two different types of sweat glands:

Our eccrine sweat glands cover most of our body. When our body temperature rises, like during exercise, we secrete a fluid, made up of mostly water and salt, directly out of our pores. This moisture is designed to help cool our body down as the fluid evaporates off our skin. This type of sweat is colorless and odorless.

Our apocrine sweat glands are a little different. They develop around hair follicles, such as in our armpits or groin, and they kick into gear when we are stressed and nervous. The fluid they secrete empties directly into our hair follicles. Like with eccrine sweat glands, the fluid is colorless and odorless -- until it mixes with the bacteria on our skin and the aluminum in our antiperspirant. Then, it creates an unsightly yellow mixture that clings to fabrics and doesn’t always wash out with normal laundering.

It’s important to note here that there’s also a difference between antiperspirant and deodorant. Antiperspirants keep you from sweating because they contain aluminum compounds that block your underarm sweat ducts and inhibit the bacteria that feed on your sweat. If you do perspire, they also help with the odor. But the aluminum is the main culprit in the chemical reaction that causes yellow underarm stains.

Deodorants, on the other hand, do not keep you from sweating; they simply mask or neutralize the body odor that occurs when you do sweat. If you use deodorant and not antiperspirant, you shouldn’t be seeing those unsightly yellow pit stains on your clothing (although you might be seeing white residue from the deodorant).

Is the Aluminum in Antiperspirant Harmful?

Concerns have been raised over the past several decades that the aluminum compounds in antiperspirants are harmful to our health, causing diseases like cancer and Alzheimer’s disease.

Our skin is our body’s largest organ, and anything that we put on it naturally gets absorbed into our bloodstream. According to the American Cancer Society, however, only a tiny fraction (0.012%) of aluminum is absorbed, “less than what would be expected to be absorbed from the foods a person eats during the same time.” ACS, therefore, maintains that “no clear link has been made between antiperspirants containing aluminum and breast cancer.” Likewise, the Alzheimer’s Association reports that “studies have failed to confirm any role for aluminum in causing Alzheimer’s.”

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Although the dangers of aluminum absorption aren’t entirely clear, we believe in taking the safe route by trying to avoid anything that’s even potentially harmful. So if you’re concerned about absorbing aluminum from your antiperspirant, you’ll definitely want to switch to a natural deodorant that doesn’t contain any. (Watch for updates about Puracy’s new natural deodorant, scheduled for a late-2019 release.)

Also, read this report from the Centers for Disease Control, which lists other possible sources of aluminum absorption you’ll want to avoid, including antacids, buffered aspirin, aluminum foil, aluminum cans, aluminum pots and pans, and some cosmetics and food additives.

Cleaning stains with Puracy Natural Stain Remover

How to Remove Armpit Stains Caused by Stress

Sean Busch, Puracy’s co-founder and resident cleaning expert, shares his simple step-by-step directions for removing yellow armpit stains from clothing that can be washed normally in the machine. He also suggests checking for stains around the collar and cuffs, since stress stains can build up there as well. (If your shirt is wool or silk, you’ll want to take it to the dry cleaner. Be sure to point out any stains when you drop it off.)

For washable fabrics, Sean recommends Puracy Natural Stain Remover, formulated with all six plant-based enzymes so that it removes hundreds of types of stains. Lipase, one of those six hardworking enzymes, specifically targets sweat-based stains. (To learn more about the six enzymes and how enzyme-based cleaners work, read Enzyme Cleaners 101: How to Quickly Eliminate Odors & Stains.)

  • Spray the affected area with Puracy Natural Stain Remover.
  • Agitate the area by rubbing the fabric together vigorously with both hands. This works enzymes deep into the fabric’s fibers, loosening the stain’s particles. You can also use a detailing brush like this one or this one, Sean says.
Sean Busch, Puracy Co-Founder

“I prefer detailing brushes made with natural boar’s hair. Sourcing the hair doesn’t hurt the animal. A boar’s hair brush, which looks like a paintbrush, has just the right amount of stiffness but is still gentle enough for fabrics.”

  • Wait for the stain remover to do its work. Let the shirt sit, preferably overnight or even longer, before laundering. This gives the enzymes enough time to fully break down the stain’s particles.
  • Repeat if necessary. Some stubborn stains may require more than one treatment. Prescription-grade antiperspirants, for example, contain more aluminum than ones that you buy off the shelf, so the stains they cause can be more difficult to remove.
  • Launder the garment normally using Puracy Natural Laundry Detergent, which also contains plant-based enzymes.

How to Remove Sweat Stains After Exercise

As noted above, the sweat you get on your workout gear is most likely from your eccrine sweat glands, so it shouldn’t be causing those ugly yellow stains. Follow the stain-removal directions above, although you may not have to agitate as vigorously, and you won’t need to wait as long before washing -- 30 minutes is usually sufficient.

Sean Busch, Puracy Co-Founder

Sean’s tip: Keep a 4-ounce bottle of Puracy Natural Stain Remover in your workout bag and spray your workout clothes before you put them back in the bag.

Cleaning Yellow Stains from White Shirts

Yellow stains on white shirts are the most difficult to deal with because they’re so… noticeable! You’ve probably even got a stash of favorite white shirts tucked away in the back of your closet that you thought you’d never be able to wear again. Follow the step-by-step directions above using Puracy Natural Stain Remover to finally get those yellow stains out -- no matter how old they are -- and you’ll soon have a renewed wardrobe.

The most important thing to note here is: Never use bleach when attempting to remove yellow pit stains from a white shirt. The bleach can actually make the stains yellower. Also, bleach kills the powerful stain-fighting enzymes in formulas like Puracy Natural Stain Remover, so never combine an enzyme-based product with bleach.

How Do You Get Armpit Stains Out of Colored Shirts?

Armpit stains on colored shirts aren’t as visible as they are on white ones, but they’re still annoying. Follow the step-by-step directions above to remove yellow stains from any machine-washable garments.

How to Get Deodorant Stains Out of Shirts

Sometimes, the pit stains on your shirt are simply a buildup of layers of white, powdery deodorant. Use Puracy Natural Stain Remover according to the directions above, agitating by hand or with a boar’s-hair brush, and let it sit as long as possible before laundering.

Sean Busch, Puracy Co-Founder

Sean’s tip: To avoid white buildup in the armpits of your shirts, let your deodorant or antiperspirant dry thoroughly before getting dressed.

How to Prevent Sweat Stains in the First Place

Sweat happens. And if you’re using an antiperspirant with aluminum, unsightly yellow pit stains are going to happen, too. When they do, you can rely on the power of Puracy Natural Stain Remover to get them out -- guaranteed. But there are also a few ways to prevent them from happening in the first place, or to lessen their effects on your clothing:

  • Switch to deodorant, which doesn’t contain aluminum and therefore won’t cause those ugly yellow stains. Better safe than sorry with the aluminum issue, as we said above. Plus, the aluminum actually blocks your pores, and that doesn’t sound too healthy or natural to us, either. (Watch for Puracy’s new natural deodorant in late 2019.)
  • Wear a lightweight undershirt or sweat guards (also called dress shields) that will help absorb the sweat before it has a chance to get to your outer shirt.
  • Cut down on your caffeine intake. It raises your body temperature, and it can make you nervous or anxious, all of which can cause sweating.
  • Whether you use antiperspirant or deodorant, always let it dry thoroughly before getting dressed. If it’s dry, it won’t transfer as easily to your clothing.

With these step-by-step stain-removal instructions and the help of Puracy Natural Stain Remover and Puracy Natural Laundry Detergent, you’ll never have to worry about ugly yellow pit stains again. Sean advises keeping a 4-ounce bottle of Puracy Natural Stain Remover in your bedroom. Simply spray the pits, collar, and cuffs of every shirt when you get undressed at the end of the day. Then just toss it in your laundry basket and forget about it until laundry day.

Does Puracy Natural Stain Remover really work? Absolutely, says Don K., who was nice enough to write us this glowing review on Amazon:

“I had some super nasty dress shirts that I was about to throw away. No matter how much I washed them, my antiperspirant deodorant was caked up inside the armpits… this was my situation before buying Puracy Natural Stain Remover. I put two squirts of this stuff under each armpit and rubbed for about 15 seconds each. Then I tossed all the shirts on the floor for the night, still wet. The next morning I washed them all using Puracy Natural Laundry Detergent. When I took them out of the dryer I couldn't believe it that the shirts looked and smelled brand new... in just one treatment!”