How to Prevent Blisters When Running: 25 Years, Zero Blisters, and the 5 Things That Actually Work
- 3 days ago
- 14 min read
Written and published August 2026 | Andy Hood, ultra and endurance runner, 25 years of running, cancer survivor
Search "how to prevent blisters when running" and you will be told the same thing everywhere. Heat, moisture and friction. Every big running brand says it.
It has been known since 1955 that this gets the mechanism wrong. A blister is not a burn, and heat is not doing what you think it is doing. I'll come back to that, because it changes what you should actually do about it.
First, a confession that is probably going to cost me. In all the years of running, the thousands, the tens of thousands of miles, the marathons, the ultras, the 100 milers, hot and sweaty conditions and days in torrential rain, I have never had a single blister. I may have just reversed that trend by committing those words to print.
Judging by my Instagram feed, many, many of you have suffered. And there is always one overriding question in your posts: how do I prevent blisters? The answer is a little nuanced, so I'll give you a little of the science, not too much because that bends my brain, then the top five ways to prevent blisters, and the five sock brands you rated most highly.
The short answer: blisters are caused by shear, the tearing that happens inside your skin when the bones in your foot slide forward while the surface stays gripped to your sock. Heat is not burning you, it just makes you sweat, and damp skin grips harder. Socks help enormously, but they are one of three levers, and the other two are shoe fit and lubrication. Get all three right and you can run a very long way on very happy feet.
🏃 Key takeaways
A blister is not a burn. A researcher called Naylor worked this out in 1955. Rubbing does heat the skin, but friction blisters look nothing like thermal burns under a microscope, and cooling the skin does not stop them forming. Heat matters, but only because it makes you sweat.
It is force multiplied by repetitions. Two things decide whether you get a blister: how hard that spot is being loaded, and how many times. This is why blisters turn up at mile 18 and not mile 2.
Damp is worse than soaked. Bone dry skin is fine. Completely wet skin is fine. It is the clammy in-between state where friction actually goes up, and that is what quietly shreds your feet over three hours.
Cotton is genuinely the enemy. In the only real-world blister research done on runners, cotton produced twice as many blisters, three times the size, compared to an identical synthetic sock.
No sock rescues a bad shoe. Fit first, sock second, lube third. In that order.
I'm a runner, not a podiatrist. This is my experience alongside the published research, not medical advice. A blister that looks infected, or a foot problem that keeps returning, belongs in front of a professional.
Blisters at a glance
The question | The honest answer |
What actually causes a blister? | Shear. Your bones slide, your skin stays gripped to the sock, and the layers in between tear |
Is it the heat? | Not directly. Heat makes you sweat, and damp skin grips harder. But a blister is not a burn |
Does moisture matter? | Yes, but damp is the worst state. Dry is fine, properly wet is fine |
Are expensive socks worth it? | Fibre and construction both matter. A cheap synthetic beats an expensive cotton every time |
Toe socks or normal? | Toe socks solve blisters between the toes. For heels and forefoot, a well-fitted normal sock does the job |
Do I need summer and winter socks? | Ideally. Thin and fast-drying for summer, merino blends for a British winter |
What is the single best thing I can do? | Get your shoe fit right. Everything else is built on that |
Contents
Everything you have been told about blisters is wrong
Go and look at the advice from the big shoe brands. One of them tells you blisters happen when your skin is damaged by heat or friction. Another puts it down to rubbing. It is repeated so often that nobody stops to check it.
Here is what actually happens.
Every time your foot loads, the bones inside it move forward while the skin on the outside, gripped by your sock, stays exactly where it is. The soft layers in between stretch. Do that enough times and they tear. Fluid fills the gap and you have got yourself a blister. The damage happens below the surface, inside the epidermis, and it has already been done by the time you feel anything.
A researcher called Naylor demonstrated this in 1955, and he did it properly. He produced blisters on 19 British medical students and doctors and took biopsies of every one. The tear had happened in the same layer of the epidermis every single time.
Blistering took anywhere between 27 and 138 repetitions depending on the person. He used the shin rather than the foot, because it is a great deal easier to work on, but the mechanism is the same. Then he varied the temperature of his apparatus and found it made almost no difference to how quickly the blisters formed.
So let me be precise about heat, because this is where most articles go wrong in one direction and a few go wrong in the other.
Rubbing does warm your skin. Studies have measured it climbing to somewhere between 41 and 50 degrees. But a friction blister looks nothing like a second degree burn, not to the eye and not under a microscope. You are not cooking your foot. Naylor showed that cooling the skin does not stop the blister, which means heat is not the thing doing the damage.
That does not make heat irrelevant, and anyone who tells you it is has gone a step too far. Heat makes you sweat. Sweat makes your skin damp. And damp skin is where the trouble starts. Blisters do form somewhat faster on warm skin, they are easier to get in summer than in winter, and skin temperature rises before a blister appears. So heat is real, it just works through the back door rather than the front.
I went through much the same thing with collagen, where the marketing and the research turned out to be telling different stories.
The thing actually doing the damage is force, applied over and over. How much load is going through that spot, and how many times. Force multiplied by repetitions. Which is precisely why blisters turn up at mile 18 and not at mile 2, and why the ultra is where your feet find you out.
Which brings us to moisture, and here is the part that surprises people. Damp skin is the worst-case scenario, because friction actually goes up. Bone dry is fine. Completely soaked is fine as well. It is that clammy in-between state that quietly shreds your feet over three hours, which is why "keep your feet dry" is only half an instruction, and why a hot day is a blister risk even though the heat itself is innocent.
That is the science done, and my brain is already aching. Here is what to do about it.
The 5 best ways to prevent blisters when running
1. Get your shoe fit right
This is the foundation and nothing else works without it. No sock, however clever or expensive, will rescue a badly fitting shoe.
You want a thumb's width in front of your longest toe, a heel that does not lift, and enough width that your foot is not being squeezed. If your heel slides, learn the runner's loop, sometimes called the lace lock. It takes ten seconds and it kills the single biggest source of heel shear.
Racing an ultra with big descents? Check you still have that thumb's width in the socks you will actually race in, because your feet will swell and every downhill mile drives your toes forward into the front of the shoe. Some runners go half a size up for the long stuff. Test it in training, never on race day.
Feet change as you get older too, in ways nobody warns you about, which I went into when I wrote about how a man's body changes in his 50s.
2. Never run in cotton socks
If you take one thing from this article, take this.
In a study of 35 long-distance runners wearing socks that were identical in every way except the fibre, the cotton pair produced twice as many blisters, and blisters three times the size, compared to synthetic.
The reason is simple. Wet cotton fibres swell by around 45%, against roughly 5% for acrylic. So a soaked cotton sock changes shape halfway through your run, changes the fit of your shoe while it is at it, and parks your foot in that clammy high-friction state for hours.
Worth flagging, because I would rather you heard it from me. Wool swells about 35%, closer to cotton than to synthetic. Merino earns its place through how it handles moisture vapour and how it keeps working when damp, not because it stays slim. Anyone selling you merino on the swelling numbers alone has not read them.
There is a useful nuance from the same researchers. When they repeated the study using thin socks, cotton and synthetic performed the same. It is the fibre and the construction together that matter, which is why a well-padded technical sock beats a thin one, and why the padding is absorbing shear rather than just adding comfort.
The military work backs this up, and with a twist worth knowing. Knapik and colleagues put 357 US Marine recruits at Parris Island into three sock systems. The standard issue wool, cotton and nylon sock left 69% of them with blisters. Swapping to a thick, dense wool and polypropylene sock worn over a polyester liner brought that down to 40%. Thickness and fibre together, exactly as Herring and Richie suggested.
Now the twist. Adding just a polyester liner underneath the standard sock made blisters more common, not less, at 77%. The blisters were less severe, but there were more of them. Which tells you that piling on layers is not automatically the answer. What you put on your foot has to work as one system.
3. Use anti-chafe cream on your feet
On my long runs I use anti-chafe cream on my feet. It stops friction, and it has the added benefit of moisturising them.
Apply it before your socks go on. Between the toes, around the heel, and anywhere you have had trouble before. On a long day out, carry a small pot and put more on at an aid station. It takes seconds.
4. Manage moisture on the long stuff
For anything over a couple of hours, plan for wet feet rather than hoping for dry ones.
On ultras, a sock change at a drop bag is one of the highest-return things you can do. Two minutes, and it resets the whole system. Always carry a spare pair, and if you are running anywhere near a Devon lane in February, make that two.
And test it in training, not on race day. That principle applies to everything, as I found out when I wrote about rescuing a training block that has gone off the rails.
5. Act on hot spots immediately
A hot spot is a blister that has not happened yet. That warm, stingy, slightly too aware feeling is your one and only warning, and you get it for a reason.
Stop. Shoe off, dry the foot, cover it with tape, a blister plaster or more lube. Every mile you run hoping it settles down is thousands more shear cycles on skin that is already failing.
Nobody has ever regretted stopping for ninety seconds at mile 12. Plenty of us have regretted not stopping.
What socks do I wear?
I am asked this a lot.
Over the years I have tried plenty of brands, from mainstream ones like Nike and Under Armour to Injinji and Balega. For the last few years I have exclusively worn Compressport, both their road and their trail range.
They work for my feet. They wick away the sweat, they do not soak up water on a winter ultra, and they have 3D microdots in all the high pressure areas. And, well, they look good too. A sock is an important part of your running gear, and much like orange running shoes, the right colour can make you faster. Science says so.
One thing worth being clear about. I switch between the road and the trail versions depending on where I am running, but I have never worn two socks at once. One pair, matched to the conditions, is the whole of my system.
The best running socks for preventing blisters: your top 5
I asked on my Instagram stories the other day which running socks you rate for preventing blisters, and the answers came flooding in.
The top five, in no particular order.
Danish Endurance. Great value and usually sold in multipacks, with merino blends for winter and lighter synthetics for summer. Targeted cushioning at the heel and toe, arch compression to stop the sock shifting, and a smooth toe seam. Budget-friendly without feeling budget.
Steigen. The Australian brand with the boldest claim in the business, a blister-free guarantee. Deliberately no cotton, wool or bamboo in them, just microfibre nylon and Lycra so they dry fast. Seamless, with a super-flat toe seam, arch support and a Y-shaped heel.
Hilly. The UK stalwart, founded in 1992 by Dr Ron Hill MBE, who happened to hold a PhD in textile chemistry as well as a Boston Marathon win. The Twin Skin is the classic anti-blister sock. Two layers that rub against each other instead of against your skin, which, given everything above about shear, is exactly the right idea.
Compressport. My own choice. The Pro Racing V4 comes in separate road and trail versions, and the trail model adds thicker sole fabric, 3D.Dots underfoot for shock absorption, reinforced zones to protect toes and nails, and padding over the ankle bones and Achilles.
Injinji. The toe socks. Every toe individually wrapped, which removes skin-on-skin rubbing between the toes completely. If your blisters are consistently between your toes, nothing else solves it as directly. They take longer to put on and they run warm on hot tarmac, but the converts are evangelical about them.
So do I put my zero blisters down to the socks? Yes. That, plus getting the right fit in my shoes, plus the anti-chafe cream on the long stuff. Three things. That is the whole system, and it has held for 25 years.
FAQs: preventing blisters
Are blisters caused by heat?
Not directly, and this is the bit almost everyone gets wrong. A friction blister is not a burn. Research going back to 1955 showed that cooling the skin does not prevent one, because the damage is mechanical, not thermal. Blisters are caused by shear, the tearing of skin layers when your bones slide and your skin does not. That said, heat is not irrelevant. It makes you sweat, damp skin grips harder, and blisters do come somewhat faster on a warm foot. So heat is a contributor, just not the cause.
Do anti-blister socks actually work?
The fibre and the construction both matter. Synthetic and merino blends clearly beat cotton, and a denser, better padded sock outperforms a thin one. But no sock rescues a badly fitting shoe, so start there.
Should I wear two pairs of socks?
It is not something I do, but plenty of runners swear by it, so here is the honest picture. A purpose-built double-layer sock like a Twin Skin is bonded and sized to work as a single unit, and the two layers slide against each other rather than against the skin. A liner and an outer sock combined at home is a different thing. In the Marine recruit study, adding a polyester liner under the standard sock produced more blisters, not fewer, at 77% against 69%, although the ones that formed were less severe. So if you are going to combine two socks, treat it as an experiment to test in training rather than a guaranteed fix, and make sure your shoes still fit with the extra bulk.
What are the best running socks for preventing blisters?
There is no single answer, because it depends on your feet and where you run. What the research is clear on is the ruling out: anything cotton. Beyond that, look for a synthetic or merino blend with proper padding, a seamless toe, and an arch band that holds the sock still. The five brands my readers rate most highly are listed above, and any of them will do the job better than what came free with your last race entry.
Are toe socks better for preventing blisters?
They are better for one specific problem, blisters between the toes. If your trouble spots are your heels or the balls of your feet, a well-fitted conventional sock does the same job with less faff at 5am.
Do I need different socks for summer and winter?
Ideally yes. Summer favours thin, fast-drying synthetics with mesh venting. Winter favours merino blends, which hold on to some insulation even when damp and cope better with a run that starts cold and warms up. Useful in British weather that can deliver sun and sleet in the same hour.
How often should I replace my running socks?
Sooner than you think. The elastic and the arch band die long before holes appear, and a sock that no longer grips your foot starts sliding, which is the exact thing you were trying to prevent. Skip the fabric softener, do not tumble dry them, and they will last far longer.
Can I prevent blisters without buying anything?
Mostly, yes. Fix your lacing, bin the cotton socks you already own, and stop the moment you feel a hot spot. Those three cost nothing.
The bottom line
Blisters are not bad luck and they are not a rite of passage. They are shear, applied over and over, to skin that is being held in the wrong place by a shoe or a sock that is not doing its job. Heat plays a part, but only by way of the sweat it produces. You are not burning your feet, you are tearing them.
Fix the fit. Bin the cotton. Lube up on the long stuff. Carry a spare pair and stop the moment something feels hot.
I have been doing exactly that for 25 years and I have never had one. Ask me after my next ultra.
Lace up and enjoy your miles.
This article is about preventing blisters, not treating them. It shares my personal experience and publicly available research, and it is not medical advice. I'm a runner, not a doctor. If you have a blister that will not heal or looks infected, or a foot problem that keeps coming back, please speak to a podiatrist, physio or your GP.
Sources and further reading
Naylor PFD. Experimental friction blisters. British Journal of Dermatology, 1955; 67: 327 to 342. (The biopsies, the repetitions, and the finding that temperature barely matters.)
Naylor PFD. The skin surface and friction. British Journal of Dermatology, 1955; 67: 239 to 248. (The companion paper on moisture and the coefficient of friction.)
Herring KM, Richie DH. Friction blisters and sock fiber composition: a double-blind study. Journal of the American Podiatric Medical Association, 1990; 80: 63 to 71.
Herring KM, Richie DH. Comparison of cotton and acrylic socks using a generic cushion sole design for runners. Journal of the American Podiatric Medical Association, 1993; 83: 515 to 522. (The follow up showing construction matters as much as fibre.)
Knapik JJ, Hamlet MP, Thompson KJ, Jones BH. Influence of boot-sock systems on frequency and severity of foot blisters. Military Medicine, 1996; 161: 594 to 598.
Blister Prevention Pro, Rebecca Rushton, for the ongoing work translating blister research into practical prevention, and in particular her more recent writing on where heat genuinely does and does not fit into blister causation.
About the author: Andy Hood
Andy Hood is an ultra and endurance runner, cancer survivor, and unapologetic advocate for men's health. After a diagnosis tried to take his running shoes off, he laced them back up and turned the experience into a mission: designing bold, attention-grabbing ultras each year to raise awareness and funds, particularly around testicular cancer. That mission includes his cheeky-but-serious menswear brand, Check Ya Balls, kit with a message that quite literally saves lives. Follow his runs, read his race reports, and grab a pair of Check Ya Balls at runningwestwardho.co.uk.
This article may include affiliate codes or links. I may receive a commission if you purchase products or services from any of the companies mentioned, at no cost to you. This goes towards running this blog, bringing you interesting articles and supporting my charity fundraising with over £27,000 raised to date.
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