Marijuana has been legalized in many states like Michigan and California for medical use it can be prescribed or you can have a license so you can sell medical Marijuana
Marijuana is legal for medical purposes in 30 states
Thirty states and Washington, DC, allow marijuana for medical purposes, although their approaches can significantly differ.
Some allow medical marijuana dispensaries and home cultivation. Others only allow home cultivation. And a few allow dispensaries but not home cultivation.
Maybe test her theory of being allergic to cats or maybe even some of the scents or something from her friends house. She should also consult a doctor to be sure.