Getting a blister on your hill day or trail run might start as a mild inconvenience, but left untreated it can go from painful irritant to total showstopper. Cory Jones of First Aid Training Co-operative looks at measures to prevent blisters, on-trail treatment, and the crucial question of hygiene in the hills.

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Blisters may seem like a minor issue—until you're limping halfway down a Munro with a long descent ahead, or pulling out of your ultra race in agony. In mountain environments, a poorly managed blister can turn a great day out into a painful slog or even trigger an infection that cuts your trip short.

Here's how to prevent, treat and manage blisters when you're out in the wild.

What causes blisters?

Blisters form when friction causes layers of skin to separate and fill with fluid. This most commonly happens on the heels, toes, arches, and balls of the feet—especially when boots or trail shoes are new or ill-fitting, socks are damp, feet are hot, or terrain is uneven.

Wet skin, grit in socks, or small pressure points in footwear can all increase the risk. Long days, steep descents and heavy packs add to the strain.

Prevention: Stop the blister before it starts

An ounce of prevention really is worth a pound of cure. These steps can drastically reduce your risk:

• Wear well-fitted boots or trail shoes: ensure they're broken in before a big trip
• Use good quality socks: Avoid cotton. Choose moisture-wicking hiking or running socks, or wear a liner sock under a thicker outer sock
• Keep feet dry: Change into dry socks when needed, and air feet and footwear during breaks
• Talcum powder or anti-chafing cream: Reduces moisture and friction
• Tape known hotspots: Apply zinc oxide or blister plaster to heels, toes or arches before setting off
• Lace footwear properly: Different lacing patterns can relieve pressure and reduce slippage

Early Action: Hotspots and red areas

A hotspot is the skin's early warning system—it's warm, maybe slightly pink, but not yet a full blister.

If you feel a hotspot:

• Stop immediately
• Dry the area and apply blister plaster, or moleskin
• Re-lace your boots to relieve pressure
• Add padding if needed to reduce rubbing

Dealing with a hotspot early can stop a blister from even forming.

Treating a blister in the hills

Despite your best efforts, sometimes blisters still appear. If they do, the approach depends on whether it's intact (not burst) or open.

1. Intact blister (fluid-filled, unbroken)

• Leave it intact if possible—the skin acts as a sterile barrier
• Cover with a blister dressing or gel pad
• Pad around the blister with soft material or moleskin to reduce pressure
• Avoid bursting unless the blister is extremely painful and you're unable to walk

2. Open or burst blister

• Clean it thoroughly with clean water or a wound wipe
• Do not remove loose skin unless it's dirty or ragged
• Cover with a sterile dressing—ideally a hydrocolloid (blister) plaster
• Pad around it to prevent further friction
• Change dressings daily or if they become wet or dirty

Hygiene in the hills

Infection is your biggest concern with open blisters. You may not be near soap and water, so stay clean by:

• Using alcohol-free cleansing wipes or saline solution to clean the wound
• Applying dressings with clean, washed or gloved hands
• Keeping spare socks dry and clean in a sealed dry bag

Carry a small blister treatment kit with:

1. Sterile wipes
2. Plasters
3. Blister plaster
4. Antiseptic cream (optional)
5. Tape or moleskin
6. Safety pin (for sterile draining if absolutely necessary)

When to drain a blister

Draining should be a last resort and only done if:

• The blister is large, painful, and making it hard to walk
• You have clean tools and the knowledge to do it safely

How to drain safely:

• Sterilise a needle or pin (boil it or clean with flame or alcohol wipe)
• Clean the blister and surrounding skin
• Puncture at the edge and allow fluid to drain
• Keep the skin flap intact
• Dress with sterile dressing and monitor for signs of infection

When to Seek Medical Attention

While rare, infected blisters can become serious—especially if you're still walking on them or in warm, damp conditions.

Warning signs:

• Redness spreading from the blister
• Swelling and throbbing pain
• Pus or foul-smelling fluid
• Fever or general illness

Infections can lead to cellulitis or even sepsis. Get off the hill and seek medical advice if you notice these symptoms.

Final thoughts: Blisters are small - but important

Blisters are easy to ignore—until they're not. Treating them early, keeping them clean, and padding them properly can keep your feet (and your expedition or race) on track.

Always carry a simple blister kit in your first aid bag and build regular foot checks into your hill routine—especially on multi-day or long-distance walks/runs. In short, blister-free feet mean a better day in the mountains.

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About the Author

Cory Jones has been an International Mountain Leader for two decades and is a wilderness first aid trainer. He is a founder member of First Aid Training Co-operative which offer comprehensive first aid courses tailored to outdoor environments—whether you're a dog walker, a mountaineer, or a mountain leader. A little preparation can go a long way when the unexpected happens.