Blisters are the major problem for pilgrims, on any path. They are caused by the rubbing of the foot's skin against the shoe, and are favoured by bacteria and oversweating. The frequent bits of asphalt road on the Via Francigena make the problem worse, as the higher temperature of the road surface is communicated to your feet through the soles. This problem should be prevented with well broken-in shoes of a very high quality and anti-blister socks, to be kept clean at all times. At every stop you should take your shoes and socks off and let your feet breathe. Before the morning start, it can be useful to rub your feet with a disinfectant and coat your fingers with vaseline to reduce friction. Walking with moist feet or socks should be avoided, so after each fording dry your feet perfectly. When you get to your evening stop, you can have a cold-water, salt and vinegar footbath, and possibly let your feet dry out in the cold to ease any inflammation. If you get blisters despite prevention (and unfortunately you almost invariably do), the old-time treatment is the best one: you carefully disinfect a needle and knotted thread, then pierce the blister from side to side to let the fluid out. You clip the thread leaving it inside the blister, so that the holes remain open and the fluid is drained during the night. Then you disinfect the area with Betadine or another antiseptic and dress it with tape - generic, not a special blister tape, or you'll see the stars – or gauze. This treatment is completely painless and, if all goes well, overnight the dead blister skin – which mustn't be removed for any reason – will dry while protecting the sensitive area.