What Is The Treatment For Skin Allergies And Rashes?

I have been suffering from skin allergies( dermatites) from my childhood. I am 21. Where ever the rash gets too bad i control it with an anti histamine and a styroid injection(decadron). But there are times when i dont respond to even a styroid. Is there a more stronger styroid i can take so that the rash( bleeding and sore) and be controlled