Sweat & Skin Problems: Why Synthetic Sportswear Can Worsen Acne and Eczema

Our skin is our largest organ and also one of the most sensitive. If you suffer from eczema, allergies, or simply have sensitive skin, you know how quickly it can react to the wrong stimulus: redness, itching, rashes, or a burning sensation. We often think this is mainly due to diet or stress, but did you know that your sportswear also plays a major role?

Why Your Skin Protests in Polyester

Synthetic fabrics like polyester, nylon, and acrylic are popular in sportswear and casual wear because they are strong and stretchy. But there's a downside: these fibers are originally plastic and trap your skin. Anyone who has sweated profusely in polyester leggings or a top knows: your skin doesn't always feel happy afterward. Red spots, itching, or even pimples after your workout are no coincidence. It's a combination of sweat, friction, and the fabric itself.

A "Mini-Sauna" on Your Skin

Synthetic sportswear often breathes less well than cotton. During your workout, it gets warm and moist under that layer, as if your skin is in a small sauna. This warm, moist microclimate causes your pores to clog faster. In combination with pressure and friction (think of a tight sports bra or straps), this can lead to acne mechanica: pimples that develop due to heat and friction.^[1]

Eczema and Sensitive Skin

For people with eczema or sensitive skin, this effect is even stronger. Sweat and overheating are known triggers that can exacerbate symptoms. Research shows that cotton is often better tolerated than synthetic fabrics because it is softer and more breathable.^[2]

Organic cotton is naturally hypoallergenic – meaning: less chance of an allergic reaction. It is grown without harmful pesticides and processed without aggressive chemicals. For the skin, this means: less chance of itching, redness, or eczema, and more comfort, even with prolonged wear.

Hidden Culprits: Chemicals in Clothing

What many people don't know: it's not just about the fabric, but also about the chemicals used in sportswear.

Dyes (disperse dyes): Many synthetic fabrics are dyed with dyes that can cause allergic reactions. Dark or bright colors are particularly notorious.^[3]

Formaldehyde finishes: This is used to make clothing "wrinkle-free" or dimensionally stable, but can trigger eczema in sensitive people.^[4]

Antibacterial coatings: Some sportswear gets a special layer against sweat odor, with substances like triclosan or silver. Sounds convenient, but can cause skin irritation or allergies.^[5]

PFAS ("forever chemicals"): Used to make clothing water- and dirt-repellent. Not only bad for the environment, but also not ideal for prolonged skin contact.^[6]

In short: what is in and on your clothes can literally end up on your skin.

Microbiome and Odor: An Additional Signal

Interestingly, your nose often gives a signal already. Polyester sports shirts smell stronger and more unpleasant after exercise than cotton shirts. This is because polyester retains moisture and bacteria differently, allowing other types of bacteria (such as Micrococcus) to dominate.^[7] This not only means more odor, but also that the skin microbiome becomes unbalanced – something that can play a role in acne and eczema.

Certifications

Not all "organic" or "natural" sportswear is equally safe for your skin. To ensure that clothing is free of harmful chemicals, independent certifications are essential. The two most important are GOTS (Global Organic Textile Standard) and OEKO-TEX Standard 100 – and they protect your skin in different ways.

GOTS: the strictest protection from raw material to finished product

GOTS is the gold standard for organic textiles. It certifies not only the finished product, but the entire production chain – from the organic cultivation of cotton to the chemicals used during dyeing and finishing. GOTS prohibits aggressive chemicals, hazardous dyes, formaldehyde finishes, and harmful coatings that can cause skin irritation.^[8] This means that GOTS-certified clothing is naturally friendlier to sensitive skin, eczema, and allergies – simply because the harmful substances were never in it.

OEKO-TEX 100: testing the finished product

OEKO-TEX Standard 100 tests the finished product for hundreds of harmful substances, including dyes, heavy metals, formaldehyde, and pesticides. It ensures that what ultimately comes into contact with your skin is safe – regardless of how or where it was made.^[9] It is a valuable extra layer of certainty, especially as a supplement to GOTS.

Why GOTS is better for sensitive skin

GOTS goes beyond just testing the finished product. It actively prevents harmful chemicals from being used at all during production. For people with eczema, allergies, or sensitive skin, this means less chance of contact with irritating substances – even in small quantities. In addition, GOTS imposes strict requirements on the softness and quality of the fibers, resulting in textiles that naturally feel more comfortable on the skin.

Below you can see exactly how GOTS and OEKO-TEX 100 deal with the four most common skin-irritating substances in sportswear:

The most important difference: GOTS prevents these substances from being used at all during production, while OEKO-TEX 100 checks that the residues in the finished product remain below safe limits. Together, they offer the best protection for sensitive skin.

What Can You Do Yourself?

Choose GOTS-certified organic cotton

This is the best guarantee that your clothing is free of harmful chemicals – both during production and in the finished product. Organic cotton is breathable, soft, and hypoallergenic, ideal for sensitive skin and eczema.

Wash new clothes first

Dermatologists recommend washing new clothes first, without fabric softener or scented products, as these can exacerbate irritation.^[10]

Avoid tight clothing

Tight, synthetic clothing increases friction and heat – precisely the triggers of skin problems. Choose breathable, well-fitting sportswear with plenty of room to move.

Pay attention to certifications, not just claims

Marketing such as "eco-friendly" or "natural" means little without certification. GOTS and OEKO-TEX 100 are independently verified and offer real guarantees.

The Conclusion

Sweat itself is not your enemy – it's the way it gets trapped in synthetic clothing that causes problems. Acne, eczema, and skin irritation develop faster when your skin doesn't get room to breathe and also comes into contact with fabrics and chemicals that irritate it.

By choosing clothing that is breathable, soft, and free of harmful chemicals, you literally give your skin room to breathe and recover. You also invest in the long-term health of your skin.

At NOHI NATURAL, we believe that sportswear should support your health – not burden it. That's why we use 92% GOTS-certified organic cotton and 8% elastane: soft, breathable, and with just the right stretch. Our entire collection is both GOTS and OEKO-TEX® certified, meaning we adhere to the strictest standards – from cultivation to finished product. The fabrics are dyed with non-toxic, low-impact dyes that comply with both certifications, so you can let your skin breathe freely without harmful chemicals. This way, you make a conscious choice, for yourself and for the planet.