Actually, it is not contaigous. It's a chemical and once it's washed away it's gone. It's really more of a chemical burn than an allergic reaction. I get it everytime I use the weedeater around the house, which is a couple times a month. I got tired of paying for Zanfel, but it does work. Now I shower in the hottest water a can stand and scratch open the blisters with a stiff brush. After drying off, I use rubbing alcohol too. It really does work pretty good. I've also had the steroid shot from the Dr. and I haven't had a really bad case since. Now I just get a few small areas here & there.