How to Prevent Chafing on a Run
Chafing comes from repeated friction, skin against skin or skin against fabric, over a distance long enough for it to add up. It's almost entirely preventable with the right gear and some lubricant applied proactively, rather than something you have to just accept as part of longer running.
Common problem areas
Certain spots come up again and again for most runners, though everyone's body is a little different:
- Inner thighs, especially on longer runs or in humid weather
- Underarms, from repeated arm swing against a shirt
- Nipples, particularly for runners in looser or older shirts
- Underneath sports bra bands and waistbands
- Neck and shoulders, where a hydration vest or pack sits
Choosing gear that reduces chafing
Snug-fitting, moisture-wicking synthetic fabrics generally cause less friction than cotton, which holds sweat and rubs more as it gets wet. Flat, seamless stitching in the areas that matter most, underarms, inner thighs, and waistbands, makes a noticeable difference over longer distances. If you're planning what to wear across different conditions, see what to wear for running in different weather for guidance beyond just chafing.
Well-fitted socks also matter more than most runners expect, since a poor sock fit can cause friction inside the shoe as well as around the ankle. See choosing the right running socks for material and fit guidance.
Using lubricant proactively
A thin layer of anti-chafe balm or petroleum-based lubricant on known problem areas before you start running is far more effective than trying to treat chafing once it begins. Reapplying at aid stations on longer races, if your problem areas tend to act up later in a run, is a common and practical habit among experienced runners.
Test it before race day
Whatever combination of gear and lubricant you plan to use on race day, test it on a long training run first. New shirts, new shorts, and new lubricant brands can all behave differently than expected, and race day is the wrong time to discover a seam that rubs. This is worth building into your marathon race week checklist alongside everything else you're finalizing.
If chafing happens anyway
Clean the area gently, avoid further friction where possible, and let it heal before your next run in the same gear. Persistent irritation, broken skin, or signs of infection are worth having a doctor take a look at rather than just managing with over-the-counter products indefinitely.
Browse upcoming events and give yourself time to test your race-day kit beforehand.
Browse eventsMy honest observation from event feedback we occasionally see passed along by organizers is that chafing complaints seem to come up more often around races in the warmer, more humid months on the calendar, which lines up with what you'd expect given how sweat and friction interact. It's a minor thing in the scheme of race-day problems, but based on what we hear, it seems to catch first-time long-distance runners off guard more than repeat racers, probably because it just hasn't come up for them before at shorter distances.
Frequently asked questions
What's the best fabric to avoid chafing?
Snug-fitting, moisture-wicking synthetic fabrics generally cause less friction than cotton, which absorbs sweat and rubs more as it gets wet.
Where should I apply anti-chafe balm?
Common spots include inner thighs, underarms, nipples, and anywhere a waistband, bra band, or pack sits against skin, though it varies by individual.
Should I reapply lubricant during a long race?
If your problem areas tend to act up later in a run, reapplying at an aid station is a practical habit many experienced runners use.
How do I know if chafing needs medical attention?
Persistent irritation, broken skin, or any sign of infection is worth having a doctor look at rather than managing with over-the-counter products alone.