I have always been an athlete, but this is something I have experienced my entire life, ESPECIALLY when I go running.  At a young age, my father told me that I was just out of shape and needed to invest time (and severe itch) into getting my body ready for working out.  Once I put the effort out, the itch began to go away, and I soon became one of the best high school runners in the state and was nationally ranked in college.  However, if I take time off, I am right back to square one, where I look as though I've never worked out before.    Might I suggest a drug-free method of working your way up to long distances.  Run a quarter mile today, half mile tomorrow, etc.  I feel that when I take long breaks from working out, I have to do this in order to get rid of the itch.  Usually within a week of consistent running, the itch goes away.  This is something I would recommend to anyone with this problem, because this has, and will forever, torment me.    Perhaps, however, you can avoid the itch all-together by taking the antihistimene until the body is in shape, then get off of it.  What I was excited about was that this didn't stop me from achieving my fitness goals, so YOU CAN BEAT IT.