What Causes Underarm Stains On Shirts?

What Causes Underarm Stains On Shirts?

Underarm stains on shirts can be a frustrating and unsightly problem. Did you know that the culprits behind these stains are not just sweat, but a combination of sweat and antiperspirant or deodorant residue? When these substances mix with the natural bacteria on our skin, they can create yellowish or grayish stains that are difficult to remove.

The history of underarm stains can be traced back to the early 20th century when antiperspirants and deodorants were first introduced. Since then, these products have become an essential part of our daily hygiene routine. However, the aluminum compounds present in antiperspirants and the fragrances and oils in deodorants can react with the proteins in our sweat, leading to the formation of stubborn stains. While there are various stain removal methods available, such as pre-treating with vinegar or using enzyme-based cleaners, it is important to choose the right method based on the fabric of your shirt to effectively combat underarm stains.



What Causes Underarm Stains On Shirts?

Understanding the Causes of Underarm Stains on Shirts

Underarm stains on shirts can be frustrating and embarrassing, especially when they become noticeable and difficult to remove. While sweat itself is odorless, the compounds and bacteria it interacts with can lead to the discoloration of fabrics under the arms. In this article, we will explore the various factors that contribute to underarm stains on shirts, from sweat composition to laundry practices.

The Role of Sweat Composition

The composition of sweat plays a significant role in the formation of underarm stains. Sweat is primarily composed of water, electrolytes, and urea. However, it also contains other substances, such as proteins, fatty acids, and lactic acid. When these substances come into contact with the fabric of shirts, they can react and cause discoloration.

One of the main culprits for underarm stains is the presence of apocrine sweat glands in the underarm area. Unlike eccrine sweat glands found on other parts of the body, apocrine sweat glands secrete a thicker, lipid-rich sweat that contains higher concentrations of proteins and fatty acids. These proteins and fatty acids can form insoluble complexes with other substances present in the sweat, leading to the yellowish or brownish stains commonly seen on shirts.

In addition to sweat composition, the pH level of sweat can also impact the formation of underarm stains. Sweat with a higher pH level, often caused by factors like diet and hormonal changes, can increase the likelihood of sweat staining shirts. The alkaline nature of sweat can react with the dyes in fabric, resulting in discoloration.

Interaction with Deodorants and Antiperspirants

Another factor that contributes to underarm stains on shirts is the interaction between sweat and deodorants or antiperspirants. Deodorants work by inhibiting the growth of odor-causing bacteria on the skin, while antiperspirants reduce sweat production by blocking the sweat glands. However, the ingredients in these products can react with sweat and cause stains on clothing.

Aluminum compounds, commonly found in antiperspirants, can react with the proteins in sweat and form insoluble complexes. These complexes can then bind to the fabric of shirts, resulting in yellowish stains that are difficult to remove. Additionally, the fragrance and coloring agents in deodorants can also contribute to the discoloration of underarm areas.

To minimize the likelihood of underarm stains caused by deodorants and antiperspirants, it is recommended to allow these products to dry completely before wearing clothing. This can reduce the chances of product residue transferring onto fabric and causing stains.

Laundry Practices and Underarm Stains

The way we launder our shirts can also contribute to the occurrence of underarm stains. Certain laundry practices can make it more challenging to remove sweat and deodorant residue from fabric, leading to the development of stains.

One common mistake is using hot water to wash stained shirts. Heat can cause the proteins in sweat and deodorant residue to set into the fabric, making it more difficult to remove the stains. It is recommended to use cold or lukewarm water when laundering shirts with underarm stains.

Additionally, using too much detergent or fabric softener can also contribute to the persistence of underarm stains. Excess detergent can leave a residue on the fabric, which can interact with sweat and create stains. Fabric softeners, especially those with oils or waxes, can also leave a coating on the fabric that can attract sweat and lead to discoloration.

Preventing Underarm Stains: Tips and Tricks

While underarm stains can be a common occurrence, there are several preventive measures that can help minimize their occurrence:

  • Choose clothing made from breathable fabrics, such as cotton or linen, to allow for better airflow and reduce sweating.
  • Consider using sweat-proof undershirts or garment shields to protect your shirts from sweat and antiperspirant stains.
  • Apply antiperspirants or deodorants to clean and dry underarms to minimize product residue transfer onto clothing.
  • Avoid overusing antiperspirants or deodorants, as excessive application can increase the chances of stains.
  • Follow proper laundry practices, such as using cold or lukewarm water, minimal detergent, and avoiding fabric softeners.

By adopting these preventive measures and implementing effective stain removal techniques, you can maintain your shirts' appearance and reduce the occurrence of underarm stains.


What Causes Underarm Stains On Shirts?

Causes of Underarm Stains on Shirts

Underarm stains on shirts can be frustrating and embarrassing. They are caused by a combination of factors, including:

  • Sweat: The primary cause of underarm stains is sweat. When you sweat, the moisture and the chemicals in your sweat mix with the bacteria on your skin, leading to the yellow or brown stains on your shirts.
  • Deodorant or Antiperspirant: Certain types of deodorant or antiperspirant can contribute to underarm stains. Aluminum-based antiperspirants can react with the sweat and cause discoloration.
  • Body Chemistry: Everyone has a unique body chemistry, and the composition of sweat can vary from person to person. Some individuals may have sweat that is more prone to staining shirts.
  • Hard Water: The mineral content in hard water can react with the sweat and deodorant residue on shirts, causing stains.
  • Improper Laundry Practices: Incorrect laundering techniques, such as using hot water or not treating the stains properly, can make underarm stains more difficult to remove.

To prevent underarm stains, consider wearing undershirts or using sweat shields to absorb sweat. Choose aluminum-free deodorants and antiperspirants, or opt for natural alternatives like baking soda or lemon juice. Additionally, treating stains promptly and using stain-removing products specifically designed for underarm stains can help maintain the appearance of your shirts.


Key Takeaways:

  • Sweat mixed with chemicals in deodorant or antiperspirant can cause underarm stains.
  • Underarm stains are more likely to occur on light-colored shirts.
  • Body oils and bacteria can also contribute to underarm stains.
  • Washing shirts with hot water can set underarm stains.
  • Using a stain remover or pre-treatment can help remove underarm stains.

Frequently Asked Questions

Underarm stains on shirts can be frustrating and embarrassing. But what causes them? Here are some common questions and answers to help you understand what causes underarm stains on shirts.

1. Are underarm stains caused by sweat?

Yes, underarm stains on shirts are primarily caused by sweat. When you sweat, your sweat glands release a combination of water, salt, and other compounds. These compounds can react with the bacteria on your skin to produce yellowish stains on your shirts.

In some cases, the type and amount of sweat you produce can contribute to the severity of underarm stains. People who sweat excessively or have a higher concentration of sweat glands in the underarm area may be more prone to developing underarm stains.

2. Can deodorants or antiperspirants cause underarm stains?

Deodorants and antiperspirants can also contribute to underarm stains on shirts. Most deodorants contain ingredients that can react with the sweat and bacteria on your skin, leading to the formation of stains. Antiperspirants, on the other hand, work by reducing sweat production, but the aluminum compounds they contain can leave residue on your shirts, causing stains.

Using clear or solid antiperspirants and applying them correctly can help reduce the likelihood of stains. It's also important to avoid applying too much product, as this can increase the chances of stains.

3. Are there any other factors that can cause underarm stains?

Other factors that can contribute to underarm stains include the type of fabric your shirt is made of and how well you maintain your shirts. Certain fabrics, such as silk or satin, are more prone to staining. Additionally, failing to properly wash or treat stains on your shirts can lead to the development of underarm stains.

It's important to choose clothing made of breathable fabrics and follow the care instructions provided to minimize the risk of underarm stains.

4. How can I prevent underarm stains on my shirts?

To prevent underarm stains on your shirts, there are a few steps you can take:

  • Choose antiperspirants or deodorants that are clear or solid.
  • Apply antiperspirants or deodorants correctly, following the instructions on the packaging.
  • Wear shirts made of breathable fabrics.
  • Wash your shirts regularly and treat any stains promptly.
  • Avoid using excessive amounts of product.

5. Can underarm stains be removed from shirts?

Yes, underarm stains can often be removed from shirts. There are several methods you can try, such as using stain removers, vinegar, or baking soda. It's important to follow the instructions provided and test any solutions on a small, inconspicuous area of the shirt before applying them to the stain directly.

If the stain persists, it may be best to seek professional dry-cleaning services or consult a clothing care specialist for further assistance.



To sum up, underarm stains on shirts are primarily caused by a combination of sweat and antiperspirant or deodorant residue. When we sweat, our sweat contains salt and other substances that can leave stains on clothing. Additionally, the aluminum compounds found in antiperspirants can react with sweat to create yellowish stains. The type of fabric and the pH level of the sweat can also contribute to the intensity and color of the stains.

To prevent underarm stains, it is important to apply antiperspirant or deodorant properly, allowing it to dry before putting on clothes. It is also helpful to choose antiperspirants with lower concentrations of aluminum compounds. Wearing undershirts made of breathable fabrics, such as cotton, can absorb sweat and reduce the stains on the outer layers of clothing. Regularly washing shirts with stain-fighting laundry products and treating stains as soon as possible can also help keep underarm stains at bay.


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