The Complete Guide to Itchy Skin During & After Exercise (+ Free Relief Checklist)

Medically reviewed by Susan Nedorost, MD, Professor Emerita of Dermatology, Case Western Reserve University. Currently practicing at Dermatologists of the Central States, Dublin, Ohio.

Every time you hit the gym, step on the trail, or roll out your yoga mat, your goal is to feel good moving.

Instead your skin flares with itching, red patches, or rashes that sometimes linger well beyond your workout.

Itchy skin during exercise - and even after - are surprisingly common. However, the triggers aren’t always easy to pinpoint.

For some, the discomfort fades quickly. For others, it can be so sore, persistent, and disruptive that you feel like stopping exercise altogether.

Here’s the good news: it doesn’t have to stay that way.

We’ve teamed up with dermatologist Dr. Susan Nedorost to bring you practical, science-backed answers and solutions. In this guide, you’ll:

• Understand the main triggers of itchy skin during and after exercise
• Learn quick relief strategies that help you move with comfort and confidence again
• Discover how simply switching fabrics can make the biggest difference

Why Does My Skin Itch When I Exercise?

Runner’s itch: often used by athletes to describe a prickly, itchy, or stinging feeling that shows up during exercise. It isn’t a medical term, but symptoms can overlap with certain types of hives (urticarias) triggered by exercise, like cholinergic urticaria.

Other triggers: for many, flare-ups are more persistent and disruptive. Often linked to:

• Fabrics and dyes
• Sweat buildup
• Friction or chafing

Sensitive skin & dermatitis: these conditions can make reactions more severe and longer-lasting.

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Types of Itching During and After Exercise

Runner’s itch

• A common phrase athletes use for that prickly, itchy, or stinging feeling that pops up during a workout
• It’s not a medical term, but the symptoms often overlap with certain forms of hives (urticarias), such as cholinergic urticaria

Cholinergic urticaria:

• is triggered when the body heats up and starts sweating e.g. during exercise, hot baths, or even stress
• shows up as small, red, itchy bumps (welts) that can sting or burn
• caused by histamine release, when skin cells called mast cells release a chemical that makes blood vessels widen and nerves react
• usually passes quickly, often within about an hour once you cool down.

Irritant dermatitis (irritant eczema):

• Also called chafing or chapping
• Happens when moisture and friction break down the skin barrier
• Common in moist areas where skin or fabric rubs during workouts

Allergic contact dermatitis (allergic eczema):

• Caused by dyes or chemicals in fabrics, or other personal care products
• Sweat leaches dyes out of fabrics and makes allergens more available to the skin
• Diagnosed with patch testing; symptoms won’t resolve unless the trigger is avoided

Atopic dermatitis (atopic eczema):

• A long-term skin condition that can flare in different ways
• Triggers may include skin irritants, allergic reactions, or sometimes even foods or medications
• Many people with eczema are also sensitive to natural microbes on the skin, like certain types of yeast and bacteria, which can make flare-ups worse

Itchy Skin During and After Exercise:
3 Causes Explained by Dr. Nedorost

1. Fabrics and Dyes

Clothing allergy is one of the most overlooked causes of prolonged rashes - and activewear is no exception.

Nearly 90% of clothing is treated with synthetic dyes. Common activewear fabrics like polyester and nylon don’t absorb dyes well. To hold color, they’re often processed with disperse dyes - some of the worst culprits for allergy!

Dr. Nedorost notes that heat and sweat can also make things worse:

“Sweat promotes leaching of the dye from the fabric onto the skin, which can cause an itchy rash that may last days to weeks after a single exposure.”

Meanwhile, fibers containing chambers (TENCEL™ Lyocell, cotton, rayon, linen, wool) absorb dyes more effectively because of their "chambers" or porous structure. That means they can be dyed with dyes less likely to cause allergy.

“The majority of dye allergy occurs from darkly dyed synthetic fibers without chambers such as polyester, nylon, acetate, or spandex,” says Dr. Nedorost.

Pro tip: Choose activewear that’s independently certified (e.g., OEKO-TEX® Standard 100). This way, you know both the dyes used are safe for your skin.

2. Sweat Buildup

Sweating is a normal part of exercise, and it’s usually beneficial for your skin.

Sweat contains natural moisturizers like urea and sodium lactate that keep the skin hydrated. It also carries antimicrobial peptides that help defend against harmful bacteria and allergens.

For people with sensitive skin or eczema, sweat can quickly flip from friend to foe if it is retained under occlusion (where skin is covered so sweat can’t escape) from garments or gloves that don’t allow air to circulate. Dr. Nedorost explains that:

“You’re more likely to have certain yeast and staph bacteria forming biofilms that cause itchy skin and are increased by moisture from occlusion.”

Other reasons sweat can trigger flare-ups include:

• Salt, lactate, and urea can sting and trigger flare-ups in eczema-prone skin. The National Eczema Association states sweaty workouts can “dry out” the skin with sodium, causing further dehydration and irritation.
• Occlusion slows the evaporation of sweat which worsens eczema.
• People with eczema often lack enough claudin-3, a protein that normally keeps sweat on the surface of the skin. Without it, sweat seeps into the deeper layers, sparking inflammation and itch.
• The wrong fabrics can also add fuel to the fire. As Dr. Nedorost notes: “Plant-derived fibers contain air-filled chambers that wick moisture from the skin. Many synthetic fabrics […] do not, leading to irritation from build-up of moisture.”

Pro tip: Shower straight after workouts to clear sweat. Skip dense, non-breathable synthetics like polyester that trap moisture.

3. Repeated Friction

Chafing is one of the most common workout skin struggles. It happens when skin rubs against skin or fabric - especially in endurance sports like cycling and running.

Over time, friction can wear down the skin’s barrier, leaving it raw, red, and stinging. In severe cases, it can blister or bleed. Dr. Nedorost explains that:

“In people with a history of childhood onset dermatitis in skin folds [like inside the elbow and behind the knee], friction from movement causes dermatitis more easily [...] Irritant dermatitis or irritant eczema can also be called chafing or chapping and is often due to a combination of moisture and friction.”

Pro tips to prevent chafing:

• Skip fabrics that trap heat and sweat or feel rough on the skin
• Avoid heavy moisturizers before workouts; use a light absorbent powder instead
• Pick breathable, moisture-wicking fibers that glide over skin (e.g., fine merino wool or TENCEL™ Lyocell)
• Reduce skin-on-skin rubbing with form-fitting activewear (e.g., opt for fitted running shorts instead of loose ones)

How to Tell If Your Activewear Is Making You Itch

Step 1: Patch Test

Dr. Nedorost recommends dermatologist-led patch testing as the gold standard. Small amounts of potential allergens are placed on the skin for 48 hours, then checked for reactions over the next 3-7 days.

Step 2: Try a Fabric Trial

No access to patch testing? Dr. Nedorost suggests this DIY method instead:

• Wear white garments (any fiber) or undyed fabrics with chambers (cotton, rayon, TENCEL™ Lyocell, merino wool) for 4 weeks
• Any outer layers like jackets, can be made of anything as long as you're not sweating or getting wet. Dry garments are unlikely to leach chemicals through another layer of fabric.

Step 3: Look Beyond Clothing

If dermatitis continues, the trigger may not be your clothes alone. Moisturizers, sunscreens, shampoos, cosmetics, and even topical medications can trigger flare-ups.

You won’t likely see your skin improving unless all allergens are identified and avoided. A dermatologist specializing in contact dermatitis can help you identify your allergens with patch testing.

Why Clothing Allergies Are Often Missed

Clothing-related skin allergies are more common than you might think - but they’re often overlooked or misdiagnosed. Here’s why:

Delayed reactions

Symptoms don’t always show up right away.

“Contact allergy to clothing, as well as to personal care products [...] is often overlooked because it is a delayed-type reaction. Contact with something that will cause a severe allergic reaction will cause no immediate discomfort. In the U.S., poison ivy is a familiar example of a delayed type allergic reaction to a plant,” says Dr. Nedorost.

Even a short 5-minute exposure can trigger rashes that last up to 4 weeks. Because of this delay, it’s easy to miss the real cause.

Limited access to testing

Diagnosis requires patch testing, but this isn’t widely available. Without it, people are often prescribed systemic medications instead of simply avoiding the allergen.

Hidden dyes and finishes

Unlike skincare, clothing labels don’t list all the dyes and finishes used. This makes it harder to trace what’s causing your irritated skin.

The good news? Certifications can help.

“OEKO-TEX labelling Standard 100 certifies that no high-risk dyes were used on a fabric. It is helpful and could be even more useful for patients if there were a way to search the internet for retail products with OEKO-TEX certification,” notes Dr. Nedorost.

Best (and Worst) Workout Fabrics for Sensitive Skin

Common Questions About Exercise and Itchy Skin

Does sweating make eczema worse?

Yes. Sweat can sting, dry out, and inflame eczema-prone skin. Extra moisture often fuels bacteria and yeast, which can cause further irritation.

Is it ok to exercise with eczema?

You can absolutely exercise if you have eczema. You don’t need to give up movement, but you may need to adapt.

If you struggle with eczema when you exercise:

• Keep workouts cool and low-impact when you start to notice eczema symptoms
• Shower promptly after activity
• Use light powders instead of heavy moisturizers in sweaty areas
• Opt for activewear made from naturally breathable, moisture-wicking fabrics like TENCEL™ Lyocell and superfine merino wool to reduce friction and flare-up.

With the right strategies, eczema and exercise can go hand in hand.

How do I know if I am allergic to polyester?

Allergic contact dermatitis to textiles in the modern era happens when you become allergic to dyes. Dye allergy is more common in synthetic fabrics, but can also occur in fabric blends used in socks, etc. Exercise can make textile allergy worse because sweat leaches dyes out of fabrics. Also, since polyester fibers trap sweat, they worsen pre-existing eczema.

Common symptoms include:

• Itching or burning sensation
• Red patches or rashes
• Swelling, blisters, or oozing (in severe cases)

Pro tip: Many of our customers with sensitive skin have found switching from polyester to TENCEL™ Lyocell activewear a game-changer for workouts and everyday wear.

Learn more: TENCEL™ vs Polyester: What’s the Best Fabric for Activewear?

Take Action

Exercise should enhance your life, not irritate your skin.

If skin flare-ups have ever made you think about stopping workouts altogether, know this: you don’t have to give up what you love.

With the right strategies, most exercise-related skin issues are manageable. Many are even preventable.

Your Evidence-Based Action Plan:

1. Identify your trigger (use Dr. Nedorost's fabric trial method above if you suspect a clothing allergy)
2. Switch to certified skin-safe activewear (OEKO-TEX®, REACH, GOTS)
3. Implement the quick relief checklist during every workout
4. Consider patch testing if symptoms persist beyond 4 weeks

Remember: sensitive skin doesn’t mean you have to stop moving. Start with one small change today. If you're ready to try activewear designed specifically for sensitive skin, we're here to help.

Shop Sensitive Skin Solutions

Try Risk-Free: All Tripulse pieces come with a 180-day comfort guarantee. If you experience any irritation, we'll refund you completely.

For more, visit:

• TENCEL™ Lyocell vs Cotton: Which Fabric Is Better for Activewear?
• What is TENCEL™ Lyocell? Everything You Need to Know
• TENCEL vs Polyester: What’s the Best Fabric for Activewear?
• Plastic-Free Activewear: Why Elastane Is Still Used (And Safer Options)

Medical Review Process: This content has been medically reviewed by Dr. Susan Nedorost, MD, FAAD, Thank you, Dr. Nedorost, for your meaningful contributions. Last reviewed: 18 Sept 2025.

Disclosure: This article is for informational purposes only and does not replace medical advice. If you have a skin condition, are unsure about your symptoms, or experience severe reactions, always seek guidance from a qualified healthcare professional. Dr. Nedorost serves as an independent medical reviewer and has no financial relationship with Tripulse.

About the Author

This article is written in collaboration with Christie Johnson (B.A. Hons, PGCert), a health and sustainability writer with over five years of experience writing in the conscious fashion space. She explores how the clothes we wear affect our skin, well-being, and the planet - translating complex ideas into clear, empowering insights. With a strong foundation in clean materials and non-toxic living, Christie's work is grounded in integrity, curiosity, and a deep care for people and the world we share.