The Science Behind Armpit Stains: What Causes Them

Are you bothered by pit stains on your shirts? We’ve all been there. When you raise your hands or lift your arms, revealing yellow stains is embarrassing.

But pit stains don’t have to plague your day-to-day life. Read on to learn what causes armpit stains and if you can prevent or remove them from your favorite shirts.

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What Causes Armpit Stains?

News flash: It’s not just sweat. Pit stains occur when the proteins in your sweat react with aluminum and other chemicals in your antiperspirant. The main contributors include:

  • Sweat: Sweat contains proteins, minerals, and other compounds. When it mixes with deodorants or antiperspirants, the residue can cling to clothing.
  • Aluminum in antiperspirants: Many antiperspirants contain aluminum-based compounds that help block sweat. Aluminum reacts with sweat's proteins, creating a yellowish stain.
  • Body oils and residue: Natural body oils and skin debris can combine with sweat and deodorants, intensifying the discoloration.
  • Detergent build-up: If clothes are not thoroughly cleaned, leftover detergent and dirt can contribute to stain development.
  • Fabric type: Certain fabrics, like cotton, are more prone to absorbing sweat and deodorant, making stains more visible.

Sweat, on its own, is odorless and colorless. Apocrine sweat glands, found in your underarms, produce a different type of sweat than eccrine sweat glands (found elsewhere on your body). Unlike eccrine sweat, apocrine sweat is full of fats and proteins, contributing to stains and odor.

Aluminum is the active ingredient in most over-the-counter and prescription antiperspirants. Unfortunately, as your armpit sweat mixes with the components of your antiperspirant, the result is a pesky yellow pit stain that’s tough to get out.

Understanding how stains form helps you prevent pit stains entirely. Here are some leading causes that contribute to those pesky sweat stains.

YOUR HAMPER HABITS

We all do it: You toss your sweaty shirt directly into the hamper until laundry day. But this creates a breeding ground for yellow stains, which are especially noticeable on white clothing.

The more time sweat and aluminum soak into your shirt, the more difficult sweat stains are to remove.

Many people make the mistake of bleaching their white shirts to get yellow pit stains out, but that makes the stains much worse.

MEDICAL CONDITIONS

A rare medical condition called chromhidrosis could also cause pit stains. People with chromhidrosis have yellow, green, blue, brown or even black sweat caused by a pigment produced in the sweat glands called lipofuscin.

People with chromhidrosis have higher lipofuscin concentrations or a higher-than-normal level of lipofuscin oxidation.

Other causes of discolored sweat include:

  • Pseudochromhidrosis: Unusually colored sweat that forms after contact with chemicals, dyes, or bacteria that produces pigments (chromogenic bacteria).
  • Hematohidrosis: Sweat that contains blood
  • Excess bilirubin: Orange-yellow pigment produced by the liver
  • Infection
  • Poisoning

If you notice these symptoms, consult your healthcare provider or dermatologist.

Can Armpit Stains Come Out?

For those who struggle with armpit stains on shirts, laundry day is a burden. Pit stains can be difficult to remove, and throwing away a shirt that’s otherwise still in good shape is wasteful.

If treated correctly (and quickly), armpit stains have a good chance of coming out of your clothing. But if you’ve sweated profusely in a shirt and let the shirt sit without treating it or have had stains set into your shirt over time, you’ll have a much harder time getting them out. 

Here are some quick tips on how to remove yellow stains from white clothes:

  • Pre-treat with vinegar: Soak the stained area in a mixture of one part white vinegar and two parts warm water for 30 minutes before washing.
  • Use baking soda paste: Mix baking soda with water to form a paste, apply it to the stain, and gently scrub with a soft brush. Let it sit for 20 minutes before rinsing.
  • Apply hydrogen peroxide: For stubborn stains, mix hydrogen peroxide with equal parts water, apply it directly to the stain, and let it sit for 15-30 minutes before washing.
  • Try lemon juice: Squeeze fresh lemon juice onto the stain and leave it in the sun for 1-2 hours before laundering.
  • Wash with enzymatic detergent: Enzyme-based detergents are designed to break down proteins in sweat, making them effective at removing stains.
  • Avoid hot water for set-in stains: Hot water can set the stain further into the fabric, so stick to cold or warm water for the initial wash.

Can You Stop Pit Stains

The best defense is a good offense. Here are several ways to  stop pit stains from forming.

  • Wear a sweat proof undershirt for protection. A sweat proof undershirt, like Thompson Tee, is the easiest, most hassle-free way to stop pit stains from ruining your clothes.
  • Change your antiperspirant or deodorant routine. You may be applying antiperspirant incorrectly or using a product that isn't suitable for your needs.Take care of your clothing. By following proper laundry protocol, you can reduce the occurrence of pit stains or make them much easier to remove.
  • Shave or trim your armpit hair. Cutting armpit hair can keep moisture and sweat from accumulating and causing stains.
  • Consider natural remedies. Supplements like vitamins B, C, and E, witch hazel, sage, brewer’s yeast, eucalyptus, lecithin and chamomile are thought to have sweat-reducing properties.
  • Use natural deodorant. Choosing deodorant (not antiperspirant) without aluminum eliminates the cause of yellow stains.
  • Avoid eating sweat-producing foods. Spicy foods can trick your nervous system into believing you’re hot, kicking your sweat response into high gear.
  • Watch your vices. Drinking alcohol and caffeine and smoking cigarettes can send signals that raise heart rate and body temperature, signaling your central nervous system to sweat more to cool down.

Say Goodbye to Pit Stains With Thompson Tee

The best way to prevent pit stains from ruining your shirts is to stop sweat at the source with a sweat proof udnershirt.

You can count on Thompson Tee as your best line of defense against sweat stains. Thompson Tee’s patented Hydro-Shield® sweat proof undershirts are guaranteed to stop 100% of sweat stains and keep ruining your favorite shirts intact.

Shop risk-free men’s and women’s sweat proof undeshirts now.

Prevent pit stains with a sweat proof undershirt from Thompson Tee