text: I work with MDs and have had the same problem in the past.  The orthopedic surgeon I work with as well as one of the general surgeons told me that plantar warts need air, and occasional light as well as moisture to "grow".  They told me to cover them with a piece of duct tape and keep them covered so they get no light or air and if it comes off in the shower to replace it as soon as you get out.  I tried it and it worked for me, just takes a while.