Good news, runners: It’s safe to pop those uncomfortable blisters. You just need to be sure that it’s really just a blister and not another type of lesion, like a wart, which should always be left to a doctor’s capable hands. A blister is usually filled with fluid and not very firm when you squeeze or press on it; a wart will feel firmer, and probably hurt if you squeeze its sides. Once you’ve decided it’s time to pop, make sure the entire area — and the tools you’re using — are completely clean to avoid infection. Sterilize a needle with rubbing alcohol or by holding it over a flame for a few seconds. Clean the blister and area immediately around it with rubbing alcohol. Then, slowly puncure the blister from the side. Let the fluid drain. When it’s all empty, clean the area again, dab it dry and apply antibiotic ointment like Neosporin and a Band-aid.