The Short Answer
Blisters affect 80%+ of multiday runners, but they don't have to end your race. The difference between a DNF and a finish is often just proactive foot care — addressing problems before they become crises. See our best shoes for 24-hour races guide for footwear recommendations.
The Prevention Protocol
| Action | When | Why |
|---|---|---|
| Pre-tape hot spots | Before race start | Leukotape on heels, balls, toes reduces friction |
| Change socks | Every 4–6 hours | Removes moisture, resets skin environment |
| Rotate shoes | Every 6–12 hours | Accommodates swelling, changes pressure points |
| Apply lubricant | Every shoe change | Body Glide or equivalent between toes, on heels |
| Immediate treatment | At first hot spot | Drain, tape, and monitor — never ignore |
Shoe Sizing for Ultras
Your feet will swell 1–2 full sizes during a 24-hour+ event. Bring shoes in your normal race size plus 0.5 and 1.0 sizes up. Start in your normal size and switch to larger shoes when tightness begins — typically around hours 6–10.
Treat Hot Spots Immediately
The most important blister rule is to stop early. A hot spot is not a minor annoyance in a multiday event; it is the warning phase before skin separation. If you feel heat, rubbing, or a small sharp point of pressure, stop at the next aid station and fix it before the skin lifts.
Dry the area, smooth the skin, apply tape without wrinkles, and change the pressure point if possible by loosening laces or switching shoes. If a blister has already formed, drain only if you know how to keep the roof intact and cover it cleanly. Dirty blister care can create a much bigger problem than the blister itself.
Crew and Drop-Bag Setup
Pack foot care so it is visible and usable when you are tired: tape, small scissors, alcohol wipes, lubricant, spare socks, and a towel in the same bag. Put one duplicate kit in a drop bag or crew box. The fastest blister kit is the one you can find without searching.
Sources
- Hoffman, M.D. (2016) — "Foot problems in ultramarathon runners." Wilderness & Environmental Medicine, 27(4), 470–478.
- Krabak, B.J. et al. (2011) — "Foot injuries in ultramarathons." Current Sports Medicine Reports, 10(5), 295–303.