High,
As mushrooms can be used like entheogen the nausea and vomitting (which I always encounter, on almost all drugs) is also named a cleaning. Like a church or mosk, you was your self is vomitting an inner cleaning before you enter the sacred trance.
If you experience the nausea like that it is no problem at all.
That why I like mush tea, come easier out of the body than chunks and vibers.
Peace,
Eric