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Frequently Asked Questions

Did you know: Millions of men and women deal with excessive underarm sweating every day. But for some heavy sweaters, it qualifies as a medical condition.


How is the Kleinerts Undershirt Line different from other "sweat proof" shirts?

The Kleinert's undershirt is the only undershirt backed by a mechanical patent from the U.S. Patent and Trademark Office. Our Sweat-Shield sweat proof technology completely absorbs and blocks sweat while maintaining breathability. Although others might say "sweat proof," no undershirt can protect you like the advanced Kleinerts undershirts. 

Original Fit vs Slim Fit: Which one is right for me?

The shirt and size you choose will ultimately depend on your fit and style preferences.

Both our Men’s and Women’s Slim Fit shirts are made with advanced TENCEL™ Lyocell fibers which are unique for their exquisite softness next to the skin and highly efficient moisture absorption.

All slim fit styles are intended to fit snugly, so they’re more discreet underneath your clothing.

The Original Fit is made from 100% premium ring spun combed cotton and are sized to provide a little more breathing room for those who prefer a looser undershirt fit. If you're looking for the most sweat protection but like the fit of a typical T-shirt, you may want to try a size up in the Original Fit shirts.

Either way, both options come with our proprietary Sweat Shield Sweat Proof Technology, backed by our Sweat Proof Guarantee!

For the complete guide to choosing the right Kleinerts size and style for you, check out our blog here.

Is the underarm barrier really sweat proof?

ABSOLUTELY YES - The Kleinert's undershirt is the only patented proprietary construction that uses a clinical-grade sweat proof material that completely blocks moisture from passing through while still allowing air to pass through.

Other shirts may advertise "sweat proof" but don’t hold the moisture well. They typically consist of a cotton layer that gets wet and stays wet against your skin becoming heavy and uncomfortable.Who needs that?

The basics of our sweat proof technology are organic fibers and highly efficient barriers unlike any other products. Plus, our shirts will not lose their effectiveness over time. That's why every Kleinerts with Sweat Shield Sweat Proof Technology comes with a Sweat Proof Guarantee. We guarantee that your underarm sweat won’t penetrate the sweat proof barrier — or your money back!

How does the sweat proof underarm barrier compare to sweat pads?

All Kleinert's products are constructed with a waterproof urethane barrier which allows moisture to evaporate.

For more in-depth information on sweat pads and garment shields, check out our website dedicated to the topic here

Can I machine wash and dry the Kleinert's undershirt? (Care Instructions)

Yes. Like other undershirts, the Kleinerts with Sweat Shield Sweat Proof Technology can be machine washed in cold or warm water and dried in medium (or lower) heat. We HIGHLY recommend turning the garment inside out when washing AND drying to ensure the fabric exposed to the skin and sweat is thoroughly cleaned AND dried. It can also be hung to line dry in the sun as well. Please do NOT use any bleach, bleach alternatives, non-chlorine bleach or any bleach byproducts in the detergent, as this will compromise the sweat proof technology.

Please do NOT dry clean. The chemicals used when dry cleaning will compromise the sweat proof technology. Please do NOT iron, as the intense direct heat from the iron can compromise the sweat proof technology. Please see your neck label for complete care instructions as well.

My Kleinert's undershirt is starting to smell. How do I stop the odor?

Everyone sweats, and sweat smells. To prevent odor from sticking around, turn the shirt inside out when washing/drying to ensure the part exposed to your skin is thoroughly cleaned and dried. Try pre-treating by applying non-bleach detergent directly to the inside of underarm area (the area touching the skin) prior to washing. Also feel free to periodically wash the shirts with "hot" water to improve cleaning. For really tough odors, repeat the steps above, but use distilled white vinegar to pre-treat the underarm area. Don't worry; the vinegar smell will wash out.

Will the undershirt shrink after laundering?

The anticipated shrinkage is built into each shirt we create, so the shirts should shrink to the designated size on our size chart. You can expect minimal shrinkage when compared to traditional undershirts.

Original Fit: We use 100% Premium Ring Spun Combed Cotton (exclusive of Kleinerts Sweat Shield) so you can expect only about a 5% shrinkage compared to traditional undergarments, which may shrink 10%-15%.

Slim Fit: We use 94% Premium Tencel and 6% Spandex. You an expect about 8% shrinkage compared to traditional undergarments, which may shrink 10%-15%.

Can I wear the undershirt right out of the package?

We recommend washing all garments prior to wearing them for the first time, especially undergarments. This will further tighten the fibers, making it softer and more comfortable. However, we use such high-quality ultra soft material that you'll find our undershirts are very comfortable right out of the package.

Can I sleep overnight wearing the undershirt?

We do not recommend sleeping overnight in the Kleinerts undershirts, as underarm sweat usually is not an issue when asleep. The Kleinerts undershirt is a functional garment, and although there is no problem sleeping in the shirt, we simply make the recommendation to maximize the utility and reduce normal wear and tear, extending the overall quality of the shirt.

How does the Kleinerts Sweat Shield sweat proof barrier work?

Our proprietary and advanced materials plus unique layering system creates hightened sweat absorption as well as air pockets which facilitates reverse osmosis — releasing your sweat as vapor and leaving you feeling cool and dry.

What is the underarm barrier made of?

Our integrated sweat proof barrier includes a stitching and layer system composed of a looped-knit bamboo fabric that soaks up sweat and an ultra-thin medical-grade urethane film that keeps sweat from leaking through.

How does Kleinerts differ from wearing a typical undershirt beneath my dress shirt?

We guarantee that your sweat will not break through our sweat-proof barrier! 

I sweat heavily. Will the Kleinerts sweat barrier work for me?

Kleinerts’s integrated underarm sweat barrier is guaranteed to block 100% of underarm sweat or your money back. If you sweat through your Kleinerts undershirt, refer to this resource.

What color options does Kleinerts offer?

All men’s Original Fit Kleinerts are available in white, black and beige.

All men’s Slim Fit Kleinerts are available in white black and beige. .

What neckline options does Kleinerts offer?

Men's Kleinerts come in crewneck, V-neck and deep V-neck necklines.

Can I easily tuck in the Kleinerts?

We designed our shirts with extra length to ensure they stay tucked in without bunching. 

What do other customers say about Kleinerts?

You can check out reviews of the Kleinerts here!

Will I feel gross or hot wearing the Kleinerts beneath my shirt?

No not at all. Once the sweat shields soak up your sweat, our proprietary layering system creates air pockets and facilitates reverse osmosis — releasing your sweat as vapor and leaving you feeling cool and dry.

Is the Kleinerts a natural solution to underarm sweat?

Yes! While most moisture-wicking materials are treated with harsh chemicals that wear off after a couple washes, Kleinerts are made from natural fibers from bamboo and premium combed cotton or Tencel. Not only do they last longer than other undershirts; the sweat-absorbing abilities also endure well beyond a handful of washes.


Why do we sweat?

Early humans ran long distances in open areas. In order to survive in the equatorial sun, they needed to cool their brains. So they evolved an increased number of sweat glands for that purpose, which in turn permitted their brain size to expand.

Read more about why we sweat.

What are some common types of sweating problems?

Of course, everyone sweats. But sometimes sweat can be the side effect of a medical issue or a condition itself. Primary (localized) hyperhidrosis is a sweating condition in which a person perspires excessively from one particular area, such as the armpits, hands or feet.

Secondary hyperhidrosis is a sweating condition in which a person sweats excessively all over the body, not just one particular area. Unlike localized hyperhidrosis, secondary hyperhidrosis is not a condition itself, but rather the side effect of another medical condition or medication.

Beyond hyperhidrosis, other sweating problems also exist, such as night sweats and situational sweating. Learn more about the different types of sweating problems here.

What is hyperhidrosis?

Hyperhidrosis is sweating beyond physiological necessity required for regulation of body temperature. It is a significant quality of life burden from a psychological, emotional, and social perspective. People of all races get hyperhidrosis. The excessive sweating can begin at any age. For many people, hyperhidrosis begins when they are a child or teen. Whether you live in a cold climate or a warm one, you can have hyperhidrosis.

Learn more about hyperhidrosis here.

How do I know if I have axillary hyperhidrosis (excessive underarm sweating)?

People who suffer from axillary hyperhidrosis sweat profusely in their armpits without warning. Often, they sweat heavily throughout the day even while sitting or in cold temperatures.

Axillary hyperhidrosis is genetic, so if someone in your family also suffers from excessive underarm sweating, you are more likely to inherit the condition. For a larger population who may not have the clinical diagnosis, heavy underarm sweating is still a daily concern.

For more information on heavy underarm sweating and how it differs from axillary hyperhidrosis, check out our page on the topic here.

What are some solutions for axillary hyperhidrosis?

Excessive armpit sweating is incurable, but there are some solutions that will eliminate underarm sweat. Kleinert's Sweat Shield Ultra clinical antiperspirant wipes ( will actually stop your underarm sweating for up to 7 days!  It has been certified by the FDA and dermatologist tested and recommended by some of the world's leading clinical dermatologists like Dr. Dee Anna Glazer from Saint Louis University School of Medicine who recommends it to her patients.

Unfortunately, many sweating solutions on the market are invasive, expensive, unproven, or worse, untested. Some solutions include underarm surgery and laser treatments. Due to the potentially irreversible side effects, it's important to conduct thorough research and speak to a dermatologist before opting for any invasive treatments.

How do I stop nervous sweating or stress sweating?

Stress and nerves are unavoidable facts of life for even the most confident people. And sweating is an evolutionary byproduct of these emotions.

Sweating under stress or when worrying over an upcoming event interferes with daily life. Wearing a Kleinerts undershirt can help curb the effects of nervous or stress sweating and the vicious sweat cycle that follows.

Want to learn more tips for stopping stress or nervous sweating? Check out our page on nervous sweating and stress sweating for more information.

What are the best undershirts and materials for sweat?

Everyone sweats for different reasons. Whether you sweat bullets when exercising or in the boardroom, you need a sweat proof shirt that can handle it.

Because Kleinerts's sweat proof barrier allows sweat to be blocked and then evaporate (unlike most cotton undershirts that lock it in), it is effective for people with axillary hyperhidrosis, those who sweat heavily on occasion and even athletes who work up a sweat at the gym or on the field.

To learn more about sweat-blocking materials on the market and which may be right for you, check out our page on the topic here.

What causes yellow stains and how can I prevent them?

Heavy underarm sweating and yellow stains seem to go hand-in-hand. But did you know that bacteria is the cause of the yellowing? 

When the sweat mixes with bacteria on the skin, they create those yellow stains that quickly ruin your dress shirts and undershirts. 


What's the Return/Exchange policy?

We gladly accept returns or exchanges on all opened or used Kleinerts up to 30 days from purchase date, so feel free to wear it and wash it! Click here for our complete Returns & Exchanges policy.

Who can I contact with questions about my order?

Please send us an email with your concerns to:

Your complete satisfaction is our top priority! Please feel free to contact us anytime!

How much does shipping cost?

Free shipping is available for all domestic orders. Standard USPS and FedEx shipping rates apply to all international orders.

For more information on international shipping, check out our Shipping and Deliveries page.

Where can I buy a Kleinerts?

You can buy a Kleinerts on our website, Amazon U.S., Amazon Canada and Amazon UK. 



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