To pop, or not to pop, that is the question. The dermatologists we spoke with answered: Pop.
"The blister will heal more readily if you drain it yourself than if it rips open later," says Jeffrey Benabio, MD, a dermatologist for Kaiser Permanente in San Diego. Sterilize a needle (by dipping it in rubbing alcohol or holding it in a flame) and use it to make a tiny puncture hole in the blister. Let the liquid (it's just water) drain out, then cover with a Band-Aid. Change the Band-Aid daily, until the skin has healed. And in the meantime, don't wear shoes that could irritate the spot.