Key takeaways
- Chafing is skin irritation from repeated rubbing, made worse by sweat, moisture, and salt.
- Common spots: inner thighs, underarms, nipples, feet, and under pack straps or waistbands.
- Prevent it with snug moisture-wicking fabrics (no cotton), anti-chafe balm, and good gear fit.
- Treat by cleaning, drying, and protecting the raw skin — and stopping the friction source.
What causes chafing
Chafing is skin damage from repeated friction — skin on skin, skin on fabric, or skin under gear — accumulated over thousands of strides. Sweat and rain make it dramatically worse: moisture and the salt it leaves behind raise friction and irritate the skin, which is why chafing peaks on long, hot, or wet days.
Common chafe points
- Inner thighs — the classic runner’s and hiker’s chafe.
- Underarms and nipples — from arm swing and shirt movement.
- Feet — friction here causes blisters, the cousin of chafing.
- Under pack straps and waistbands — hips, shoulders, and lower back.
Before a long run, a runner coats their inner thighs and underarms with anti-chafe balm, wears fitted wicking shorts instead of loose cotton, and re-applies balm at the halfway point on a hot day.
Prevention and treatment
Prevent it with snug, seamless moisture-wicking fabrics (never cotton), anti-chafe lubricant on known spots, dry skin, and good gear fit. To treat, clean and dry the area, apply a protective ointment, and — crucially — eliminate the friction source so it can heal.
The bottom line
Chafing is one of the most common and most preventable trail ailments. Snug wicking layers, anti-chafe balm on known hot spots, and well-fitted gear stop it before it starts — and treating a hot spot the instant you feel it keeps a minor annoyance from turning into raw, trip-ending skin.
Frequently asked questions
What causes chafing?
Chafing is caused by repeated friction — skin rubbing against skin, clothing, or equipment — over many strides or miles. Moisture from sweat or rain and the salt left behind make it far worse by increasing friction and irritating the skin, which is why it flares on long, hot, or wet outings.
How do you prevent chafing?
Wear snug, seamless, moisture-wicking fabrics (avoid cotton), apply an anti-chafe balm or lubricant to hot spots before you start, keep skin as dry as possible, and make sure clothing and pack straps fit without rubbing. Addressing any 'hot spot' the moment you feel it prevents it becoming raw.
How do you treat chafed skin?
Gently clean the area, pat it dry, and apply a soothing protective ointment; cover broken skin if needed and let it heal. Most importantly, remove the source of friction — change wet clothing, adjust straps, or add lubricant — so it doesn't get worse on the rest of the trip.
Sources
- Skin care for endurance athletes — American Council on Exercise
- Trail running health — American Trail Running Association