How to Prevent Chafing While Running: Thighs, Nipples, Underarms and Bra Lines, and How to Treat Chafed Skin

You usually find out in the shower. Warm water hits the inside of your thighs or a line under your bra band, and the sting shows you exactly where your clothes were rubbing for the last hour. Chafed skin isn't a serious injury, but it's one of the most common reasons runners start dreading the long run.

It can feel personal, too. Thigh chafing gets blamed on body size, nipple chafing gets laughed at, and plenty of runners quietly shorten their runs or give up on summer running instead of looking up how to stop chafing.

Chafing has a plain cause you can change: skin rubbing against skin or fabric thousands of times, made worse by sweat. Below you'll find what causes chafing, where runners get it and how to protect each spot, how to choose clothes and lubricants, what to change on hot days and long runs, and how to treat chafed skin when it happens anyway.

What Causes Chafing When You Run?

Chafing is a friction injury to the outermost layer of skin. The Cleveland Clinic describes it as rubbing that wears away and damages the skin, with friction as the root cause in every case. It looks like a scrape or a mild burn: red, raw, stinging skin, sometimes with small cracks or spots of blood. A foot blister is a different injury, where the layers split under an intact surface, and our guide on how to prevent blisters while running covers it.

Sweat is what turns a mild rub into raw skin. Gerhardt and colleagues (2008), at the Swiss materials-testing lab EMPA, had 22 adults rub their forearms across a fabric at different levels of skin hydration. In every person, friction climbed in a straight line as the skin got wetter. Normally moist skin produced 43 percent more friction than very dry skin in women and 26 percent more in men, and completely wet fabric produced more than twice the friction of natural skin on dry fabric. The authors traced it to softened skin making fuller contact with the fabric and gripping it.

Then there's repetition. During a half-hour run at around 170 footfalls a minute, your inner thighs brush past each other about 5,000 times, and your arms swing past your sides just as often. A seam that's barely noticeable on a walk becomes a problem on that many passes, especially once dried sweat leaves salt on the skin and in the fabric.

Chafing is one of the most common skin complaints runners have. Purim and Leite (2014) examined 76 road runners in southern Brazil and found that 42 percent reported chafing. It showed up at every training volume, from 39 percent of those running under 25 km a week to 57 percent of those covering 65 km or more.

How to Prevent Chafing While Running: 6 Rules

These six rules cover nearly every case of chafing, whatever part of your body it hits. The sections after them explain how to apply each one to the thighs, nipples, underarms, bra lines and groin.

1. Wear fitted, moisture-wicking fabric with flat seams. Clothing that stays put and dries fast takes away most of the rubbing.
2. Put fabric between skin that touches. Compression shorts or half tights end skin-on-skin contact at the thighs.
3. Lubricate before you sweat. Apply a lubricant or barrier to every spot that has chafed before, on clean, dry skin.
4. Top it up on long runs. Lubricants fade as they soak into clothing, so reapply roughly every hour on long or hot runs.
5. Cover your nipples for long runs. A small adhesive cover or a strip of tape prevents the most painful kind of chafing.
6. Get out of wet clothes soon after. Change and rinse off the salt within an hour of finishing.

Where Runners Chafe and How to Protect Each Spot

Inner thighs

Thigh chafing is skin-on-skin friction, so the fix is to put something between the skin. Compression shorts, half tights or shorts with a built-in tight liner end the contact completely. If you prefer loose shorts, choose a longer inseam that doesn't ride up as you stride, because a hem that creeps upward drags across the skin it uncovers. Fitted thigh bands do the same job under a running skirt. Add a lubricant to the inner thighs before you start on days when you'll sweat heavily.

Nipples

Jogger's nipple is chafing from a shirt sliding back and forth across the chest, and on long runs it can bleed through a top. It has been in the medical literature since at least 1977, when a letter titled "Jogger's nipples" appeared in the New England Journal of Medicine (Levit, 1977). A dermatology review by Mailler-Savage and Adams (2006) found reports of it in 2 to 16 percent of runners on marathon day.

Distance is the big risk factor. In Purim and Leite's survey, jogger's nipple affected 3.6 percent of runners covering under 25 km a week, 6.2 percent of those at 25 to 64 km, and 35.7 percent of those at 65 km or more. The authors pointed to coarse or nylon shirts rubbing the chest as the likely cause. The fix is a smooth, soft technical top that fits close, plus a small adhesive nipple cover, a plain bandage or a strip of tape on any run over an hour. A dab of lubricant works for some runners, though sweat can wash it off before the run is over.

Underarms and inner arms

Your arms swing past your torso on every stride, so the armpit and the inside of the upper arm chafe wherever a sleeve seam or the edge of a singlet sits. Look for tops with seams that sit away from the armpit, or sleeveless tops cut wide enough that the edge doesn't brush the skin. A balm stick is the easiest product here, because you can reapply it mid-run without getting your hands greasy.

Sports bra lines

The underband, the straps and the clasp all press into skin and move with every step, which is why chafing along the bra line is so common. It's often a fit problem. Wakefield-Scurr and colleagues (2024) note that athletes report sports bras causing chafing and even cuts. When the team assessed 142 elite UK female athletes preparing for the Tokyo Olympics and Paralympics, most were wearing ill-fitting, loose bras. After an individual fitting and four weeks in a new bra, 97 percent rated it better than the one they'd been wearing.

A good running bra band is snug enough that it doesn't ride up when you raise your arms, and the straps sit flat without digging in. Check where seams and clasps land, and put a balm or a strip of tape along the band on long runs. If one spot keeps chafing in a bra that fits, try a different cut before you buy more tape.

Groin and waistband

The groin is a skin fold that stays hot and wet, with liner and underwear seams rubbing through every stride. Skip cotton underwear under running shorts and let a smooth built-in liner or compression shorts do the job. A lubricant along the crease of the leg helps on long runs. At the waistband, a drawcord knot or a tucked gel packet can rub a raw patch in the small of the back, so check what sits against your skin before you start.

Clothing That Prevents Chafing: Fabric, Fit and Seams

Gerhardt's finding that wet fabric more than doubles skin friction is the best argument against running in cotton. A cotton shirt soaks up sweat and stays heavy and damp, so it rubs harder with every mile. Synthetic running fabrics such as polyester and nylon, and fine merino wool, move moisture away from the skin and dry faster.

Fit matters as much as fabric. Clothing should move with you, not across you. Loose fabric slides back and forth over damp skin, while very tight clothing digs in at the edges. Look for:

• Flatlock or bonded seams that lie flat instead of forming a ridge.
• No tags, or tags printed straight onto the fabric.
• Seams placed away from the armpit, inner thigh and nipple line.
• Shorts that stay put, whether that's a built-in liner, compression shorts or a longer inseam.

Test new kit on a short run before a long one. A top that's fine for 30 minutes can rub a line across your chest by minute 90, and race day is the worst time to find that out.

Anti-Chafing Lubricants and Barrier Creams by Type

Every anti-chafing product does one of three things: it makes skin slippery, it lays down a barrier, or it keeps skin dry. In the US, petrolatum, dimethicone, zinc oxide and topical starch are all on the FDA's list of approved over-the-counter skin protectant ingredients, and the same rules (21 CFR Part 347) let products made with petrolatum or dimethicone say they temporarily protect chafed skin. Here's how the main types compare.

How long a lubricant lasts

This is the part runners underestimate. In a lab test at Imperial College London, Yap and colleagues (2021) measured skin friction under wax-and-oil lubricants made for health workers wearing tight face masks. Their best blend, beeswax with olive and mineral oil, cut friction by 87 percent right after it went on, but only by 59 percent four hours later. The authors noted that oil soaking into the material pressed against the skin is a key reason lubricants stop working. Running clothes do the same thing to your lubricant, so on runs past an hour or so, carry a small stick or a single-use packet and top up the spots that matter.

Apply any product to clean, dry skin before you warm up. Lubricant spread over sweaty skin slides off instead of sticking, and you'll miss the edges of the area that needs it.

Hot-Weather and Long-Run Chafing Tips

Heat and humidity mean more sweat and slower evaporation, which puts skin in its highest-friction state for longer. Long runs add the repetitions. On those days:

• Lubricate generously and early, before you leave the house.
• Carry a top-up: a small balm stick fits in a pocket or a belt.
• Pour water over your head and neck to cool off, not over your shorts or chest, because soaked fabric rubs hardest.
• Choose light, minimal kit that sheds sweat quickly.
• Change straight after, and rinse off the salt as soon as you can.

Hot days also slow your pace, and our look at whether it's easier to run in the cold or the heat covers how much. Winter isn't chafe-free either. Thick layers trap sweat against the skin, which is why our guide on how to dress for cold runs starts with a moisture-wicking base layer.

How to Treat Chafed Skin After a Run

Most chafing heals on its own within a few days once the rubbing stops, according to the Cleveland Clinic. The goal is to keep the damaged skin clean, protected and dry enough to heal.

1. Stop the rubbing. Change out of the clothes that caused it as soon as you can.
2. Clean it gently. Use lukewarm water and a mild soap, and pat the skin dry instead of rubbing it with a towel.
3. Soothe and protect. The Cleveland Clinic suggests aloe vera and a thin layer of petroleum jelly. A zinc oxide cream works well overnight on skin folds.
4. Let it breathe. Wear loose, soft clothing until the skin settles, and skip anything alcohol-based or perfumed, which stings raw skin.
5. Protect it on your next run. Cover a raw patch with a non-stick dressing and lubricate the skin around it, or take an easy day off.

Treatment for chafing in the groin area is the same for men and women: keep it clean and dry, use a barrier cream, and wear loose underwear while it heals. Groin rashes that itch, spread or don't respond within a few days need a doctor, for the reasons below.

When Chafing Needs a Doctor

Chafing that keeps getting worse can turn into intertrigo, an inflammatory rash where two skin surfaces touch. Kalra and colleagues (2014), writing in American Family Physician, describe how friction and trapped moisture break the skin down and open a door to fungal and bacterial infections, including Candida yeast and streptococcal bacteria, which need antifungal or antibiotic treatment. See a doctor if:

• The skin hasn't improved after a few days of care, or keeps getting worse.
• You see signs of infection: oozing, pus, crusting, spreading redness, swelling, warmth or a fever.
• A red rash in a skin fold has small separate red spots around its edge. That pattern is typical of a yeast infection.
• You have diabetes or a weakened immune system, which makes skin infections more likely and slower to clear.
• A nipple keeps bleeding or doesn't heal, or you notice changes that don't match where your shirt rubs.

Before Your Next Run

Chafing comes down to skin, friction and sweat. Wear fitted technical fabric with flat seams, put a layer of fabric between your thighs, lubricate every spot that has chafed before while your skin is still dry, cover your nipples on long runs, and top up as the miles add up. If it happens anyway, clean the skin, protect it and let it heal before it becomes a bigger problem.

Small problems like chafing are often what quietly ends a running habit. If sticking with exercise is the harder part, our roundup of the best fitness apps for staying consistent compares tools built around that problem. FitCraft is one of them: an AI coach demonstrates every exercise as a 3D character and calls you by name, while streaks and leaderboards give you a reason to come back the next day.