Gingerols, shogaols and what drying changes
Fresh ginger is dominated by gingerols, the pungent compounds responsible for much of its bite. When ginger is dried or heated, gingerols dehydrate into shogaols, which are typically more pungent and biologically more potent in laboratory assays. This is why dried and fresh ginger can behave somewhat differently, and why extract standardisation usually reports both classes.
The anti-nausea and anti-inflammatory routes
Ginger compounds inhibit cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, the same arachidonic-acid pathways that produce inflammatory prostaglandins and leukotrienes, which is the mechanistic basis for its mild anti-inflammatory reputation. For nausea, the better-supported route is interaction with the 5-HT3 serotonin receptor in the gut and with gut motility, dampening the signals that trigger the vomiting reflex.
Controlled trials most consistently support ginger for pregnancy-related and post-operative nausea; evidence for other uses is weaker. Pregnant people and anyone on anticoagulants should check with a clinician first. This is general educational information, not medical advice.