The . The thing you need to know about blood blisters is once "popped, " they are very susceptible to infection. The bloody fluid is a perfect media for bacterial growth. With that in mind (assuming you're in a state of good health, not a diabetic or have poor circulation or are taking any blood thinners), go ahead and pop it. Get it from the side, where the skin meets the blister, and use a sterile instrument. Wash it with soap and warm water, and keep it clean and dry with a dry, sterile dressing (a band aid is ok). Don't use any topical antibiotic like bacitracin, neosporin, etc. Just keep it clean and dry until it's no longer "open" (draining). You might see a light red ring around it after a day or so, which is normal inflammation you need to heal. Watch for signs of infection: increased pain, increased drainage or pus, swelling, redness, foul odor. At the first sign of infection, head to your doctor for a prescription for an antibiotic. Try not to get arrested for practicing medicine without a license!