"Claiming medical marijuana on income taxes. "
That is a very interesting question. I will break this down into a few answers:
The federal government does not recognize medical marijuana as being a valid form of medicine and it is federally illegal so in terms of taxes on that level definitely not.
In terms of the state level, although cannabis may be legal it is not something you can claim on in terms of healthcare expense or otherwise, for healthcare deductions for instance.
In terms of making money off of cannabis, if you are earning an income, then yes you must pay taxes on that.
I hope this helps.