Why blisters take hold on the fells

A blister is nothing more than friction, moisture and heat teaming up on soft skin. On a long distance walk those three ingredients are almost always present: the same foot repeating the same movement thousands of times, a boot that flexes slightly differently on a descent than it does on the flat, and a sock that has quietly become damp after a boggy crossing or a sweaty climb out of a Lakeland valley.

What makes upland walking so unforgiving is the terrain. A gentle towpath walk gives your feet a rhythm; a day on the Yorkshire Dales or the Scottish hills gives them constant variety — sideways camber, loose scree, wet peat, endless stone steps down from a summit. Each of those changes the pressure points inside your boot. Most blisters start as a "hot spot" long before there is any visible damage, and that early warning is the single most useful thing your body will give you all day. Learn to stop for it, not push through it.

Get the fit and the socks right before you set off

Prevention starts weeks before the walk, not at the car park. Boots need to be broken in properly, but more importantly they need to be the right size and shape for your feet. Feet swell over a long day and shift forward on descents, so aim for about a finger's width between your longest toe and the front of the boot, and check that your heel lifts no more than a few millimetres when you walk uphill.

• Wear two layers — a thin, snug liner sock that wicks moisture away, and a cushioned outer sock. The friction then happens between the two socks rather than between sock and skin.
• Choose merino wool or a good synthetic blend over pure cotton, which holds water against the skin and stays damp for hours.
• Avoid seams over the heel and little toe, and check socks for grit, sand and folded fabric every time you put them back on.
• Use heel-lock lacing — lacing the top section so the heel is pulled firmly into the back of the boot — to stop the foot sliding forward.
• Trim toenails straight across and keep them short; a long nail on a long descent is a reliable way to lose it.

Manage your feet through the day

Long distance walking is a game of small maintenance stops. Take your boots and socks off at lunch, especially if your feet are wet, and let them air in a breeze while you eat. Dry your feet with a dedicated small towel, not your fleece. If you use powder, apply it to dry feet only — powder on damp skin turns into a gritty paste that does more harm than good. If you prefer a lubricant or barrier cream, apply a thin layer before you start and top it up at lunch, and keep the tube well away from your water bottle.

Change your socks at the halfway point if you can. A fresh, dry pair mid-afternoon costs you three minutes and can save the last five miles. If a stream crossing or bog soaks your boots, wring your socks out, wring them again, and accept that the last hour will be damp — but get them dry overnight.

Treat a hot spot immediately

The moment you feel that telltale burning, stop. Not at the next summit, not at the next gate — now. A hot spot treated in thirty seconds becomes a non-event; a hot spot ignored for an hour becomes a blister you will feel for the rest of the week. Take the boot and sock off, dry the area thoroughly, and cover it with a smooth, low-friction dressing. A hydrocolloid plaster or a piece of soft adhesive tape applied without wrinkles will do the job, but never let the edges curl — a folded edge is a new friction point.

Some walkers swear by smearing a little lubricant over the hot spot before the dressing goes on; others find tape alone is enough. Test your approach on shorter walks first so you know how your skin reacts.

If a blister has already formed

A small, intact blister is best left alone — the roof of skin is a sterile dressing. Pad around it with a doughnut of soft foam or felt so pressure lands on the surrounding skin rather than the blister itself, then cover the whole thing.

If a blister is large, painful and clearly going to burst with the next mile, you can drain it with a sterile needle, but do it carefully:

• Clean the area and your hands first, and use a fresh sterile needle or a needle passed through a flame and allowed to cool.
• Prick the edge, not the centre, and let the fluid drain by gentle pressure. Leave the roof of the blister intact.
• Cover with a hydrocolloid dressing or a sterile non-adherent pad and tape, and check it every couple of hours.
• Do not drain a blood blister, and do not drain anything if you have diabetes, poor circulation or a weakened immune system — seek proper medical advice instead.

Watch for signs of infection: increasing redness, swelling, heat, throbbing pain or pus. An infected blister on a remote hillside is a genuine problem, so if it is spreading, get off the hill and get it looked at.

An overnight routine that pays off

At the end of the day, wash your feet in cool water, dry them properly — especially between the toes — and let them breathe. Keep your boots clean and dry, pull the footbeds out overnight, and stuff the boots with newspaper if they are sodden. Check your socks for thin patches and grit.

Carry a small foot kit on every walk: a couple of hydrocolloid plasters, a strip of zinc oxide tape, a little gauze, a sterile needle, a small pair of scissors and a sachet of lubricant. It weighs almost nothing and it will be the most useful thing in your rucksack on the day the weather turns, the miles drag and your feet decide to remind you who is really in charge of the walk.