How can you tell if you have an infection under a blood blister? I had a rock in my shoe and did not know it 3 hours later I had a large blood blister that I did not pop. It calisted over and then I sanded it down and put a needle in it, I got a yellowish

The . The easiest way to discover if you have infection near that blister will be to look for surrounding redness and tenderness. If there is, then most likely you have an infection. The next thing is to look for malodorous and pus drainage coming out of your foot. If you have any of that, then definitely you have an infection and you need to visit a podiatrist. If you are diabetic however, you might have an infection and still not have any surrounding redness. So, if the wound on your foot generally looks bad and not healthy, then it's better to just come and visit a physician rathen than wait and see if it will get better. You are more likely to cause more harm by trying to treat it on your own.
SImple means. You need to identify why the blister developed and eliminate that problem. Then, the keys are to cover and protect the injured area with dressing changes every other day to allow healing. Remember that inflammation (red, hot, swollen and tender) are important parts of healing and do not necessarily mean infection. If the wound is healing, it cannot be infected. If it gets worse, see a doctor.