Have you always gotten this? Do you get it if you wear long sleeves? The reason I ask is that depending on the season there may be agricultural debris floating about. Here in the central valley of northern CA we've all complained about itchy arms but it is only seasonally. Wheat chaff can really be a pain! You may have more of a topical allergy that would be better treated topically or just by wearing long sleeves (I know, I know). Some people get itchy skin just from sun exposure.