What causes a blister?
I'm not a medical expert (or anything like!) but it appears that the blisters walkers are most likely to encounter are water blisters, where a watery colourless liquid is trapped underneath the outer layer of skin. This is usually caused through friction - where the outer layer of skin is being rubbed or is being rubbed against the layer underneath. There are other types of blister and of course other causes (burns, disease, etc) but these are not the subject of this. Please note that this article does not constitute medical advice or guidance; it just represents some of the information I've managed to find and, in some cases, try. As always, if you are in any doubt please consult a doctor, especially if there are any signs of infection.
The usual cause of a blister during walking is friction. There are other factors that will exacerbate this including dampness and heat, but this is normally caused by a walking boot not fitting precisely everywhere around the foot that it should. This may make your socks rub against the skin, or the sock itself will rub the top layer of skin against the next. As those who have had blisters, the end result can be painful and make walking quite unpleasant.
My quest is to find a way that prevents blisters happening at all, but before that let's see what suggestions there are to alleviate the problem once you've got it.
What to do when you've got a blister?
The most important thing to do is to recognise that a blister is forming and act immediately if at all possible. I can absolutely recommend acting quickly; it doesn't necessarily prevent the blister forming, but it certainly makes it easier to live with. You will start to feel something start to hurt, just gently at first but soon it will get worse. Act now!
Blister plasters are available from chemists and supermarkets. These have a gel that goes against the skin and blister that really helps soothe the blister. Several brands are available - I've tried a couple and found no difference in how well they alleviate the pain. What I do recommend, however, is to buy the (more expensive) branded versions that come in larger sizes to cope with larger blisters. I now carry a small pack of these in my rucksack. The individual parts are also available from some sports shops if you want to 'make your own'.
Dry the foot. A sweaty foot will be worse than one that's dry. Damp skin is likely to be softer and therefore rub more easily and blister. Changing socks during a walk is often a good idea anyway to make feet feel fresher anyway, so changing may help. I've tried this too - it does help, but is not the perfect cure.
Let the foot heal. Any healing of the skin is best done in the open air - so once you've finished the walk let your feet out! Leave the plaster on until you get home or back to base, but then leave it open if at all possible.
What do to to prevent blisters?
As noted above my quest is to prevent blisters happening at all, not to suffer them and have to cure them. Prevention better than cure! However, it is clear that some people get blisters whatever they try, and what follows are some of the suggestions that I have found to help prevent them.
Fit your boots! From the many articles, blog posts and forum messages I've been through the biggest single reason is that boots or shoes do not fit properly and are causing rubbing and ultimately blisters. But getting boots that fit correctly is not always easy, especially if your feet are not of the textbook proportions. This is the problem that I've had. Last summer I ended up with a collapsed transverse arch in my right foot - according to the physiotherapist it was age related, terrific. The various exercises have however fixed this up a treat by literally exercising muscles I didn't even know existed, but it does appear that the overall shape of my right foot has changed, hardly surprising really. As a result the Zamberlan boots that fitted perfectly for a long time don't fit perfectly any longer. I have tried insoles and different lacing but neither have worked completely. I now find the boot being able to move slightly against the heel, although the left boot remains fine. I can only conclude that my foot has narrowed slightly meaning the fit to the front is slightly easier therefore the foot is further forward than it was before leaving a small gap at the heel. Remember that tight shoes or boots can be just as much of a problem as loose fitting versions - you're just likely to get blisters in a different place. Heels should not slip and there should be enough room at the front for you to wiggle your toes.
Use lighter boots. I have another pair of boots that are much lighter than my once trusty Zamberlans and I have never suffered with blisters, probably as there is more flexibility in the boot uppers and my feet don't have a chance to move around and rub. The downsides are that these don't provide the same level of support and are sweatier and a bit whiffy after a day's walk...
Talcum powder. Keeping your feet dry, be that from sweat or puddles/streams/rivers is certainly going to reduce the likelihood of blisters. By shaking a cloud of talc into both your socks and boots you will reduce the dampness. It will also feel smoother against the skin and reduce the friction. I have tried this and it does appear to help - but you will probably need a top-up of talc throughout the walk to keep feet dry. Don't breathe in the talc though as there are some suggestions it may be harmful.
Change socks. Taking a spare pair of socks with you is always a good idea, but making the effort to change them is something that is often cast aside. Do it! This will help keep feet fresh and ensure you have a dry sock against the skin.
Different socks. Socks are available that will wick away any sweat to help keep your feet dry, just like a base layer will help to wick sweat away from you. These can be synthetic or from merino wool. I have yet to try these, but others do think they work and are worthwhile.
Socks with high wool content. The socks I have always used are high in wool, but there are suggestions that they should have at least 70% wool content. I cannot test this as the socks I have are all like this.
Use two socks. The theory goes that if you wear two pairs of socks, the outer pair will rub against the inner pair rather than your skin thereby reducing blistering as your skin is protected by the inner socks. I've tried this by using a pair of quite thin socks inside the normal walking socks. It was a failure, not necessarily because the theory is wrong, probably more because my boots became a bit tight across the boot with two socks and thus didn't have the room to move against each other and I still ended up with a blister on my heel. I do, however, intend to try this again with different socks.
Dual layer socks. As with using two socks, the theory is that the outer layer will rub against the inner layer rather than against the skin. Such socks usually have an inner layer from material that will help wick sweat away, so should be an affective solution. But one I have not tried.
Use the right socks. Different weather, conditions, climate and temperature should demand appropriate clothing and footwear. Socks are just as important as the boots or shoes. Be kind to your feet!
Blister plasters. If you are prone to blisters, using a blister plaster before you start walking can help prevent them if you ensure you apply them where blisters are likely and cover the entire areas. This did work well, but is not quite the same as not getting them at all - these plasters are not inexpensive. They may also be rubbed away, which of course if much better than the skin being rubbed, but can be slowed using surgical tape.
Vaseline. I have not yet tried this but several suggest that putting a layer of vaseline of your feet underneath socks can help. This strikes me as a messy solution! There are other proprietary brands that may help and do not thin out as quickly as vaseline.
Surgical Spirit. Again, I haven't tried this but the theory is that rubbing surgical spirit into your feet for a week or so before a long walk can help harden the skin.
Stay hydrated. I had always assumed this applied more to the rest of you than feet, but the advice to stay hydrated and drink enough water is solid on the basis that your body will do much of the work for you. You will perspire freely rather than producing tiny salt crystals (which would increase friction). But as above, getting the sweat away probably does need some assistance from the right socks.
Walk in bare feet. Not out on the trail, but when at home. This certainly helps to harden the skin, but more particularly on the sole rather than where blisters are likely. I do try to during the summer but I don't particularly like cold feet!
Cut your toenails. Long toenails are often the cause of toes rubbing and blisters. Keep them short.
Soak your feet in tea. Soaking your feet in strongly brewed tea can, apparently, make your skin tougher. I assume milk and sugar are not helpful...
As noted I have not personally tried all of the above. Some may work for you, some may not. I present them here to offer suggestions you may find worth trying. The important bit is that blisters are caused by rubbing, often made worse by heat or damp. Reduce those factors in whatever way works for you and you will reduce the chance of blisters. The most critical aspect is the fit of your walking boots or shoes.
My own experience after starting to suffer from blisters after years of no problems was to change the boots given my right foot has changed shape. I have now moved to a different pair fitted by the good folks at Outside in Calver and have, so far, no problems.