I had problems with that for YEARS. I finally started using the Schick Intuition razor -- the one with the soap attatched to the razor -- and I use the sensitive skin variety (not the normal one, that one made it worse for me). I also shave my underarms EVERY DAY, because if I quit for even one day I cut myself and get razor burn. The razor burn hasn't completely gone away but it's a LOT better than when I first started shaving.