My girlfriend has POTS (Postural orthostatic tachycardia syndrome). She experiences nausea, dizziness, headache, fatigue, fainting and heart palpitations. Recently has tried smoking marijuana to explore its positive effects. She says that it helps the nausea, but is afraid to continue using incase of unforeseen negative effects. Would it be a good idea to continue this or is it risky or even dangerous?

Summarized question: Is marijuana risky for one with postural orthostatic tachycardia syndrome?