It looks like medically it is legal in IL
http://www.dph.illinois.gov/topics-...ness/medical-cannabis/debilitating-conditions
However headaches is not on this list nor am I willing to risk my job loss if I turn positive for a random drug screen which I am not protected under in the State of Illinois even if I'm qualified for the prescription itself. Illinois is at will state. Can be fired for any reason including a failed drug test