How does ginger work to alleviate nausea?

Ginger has long been used as a natural folk remedy for nausea and vomiting in pregnancy, but its exact mechanism of action remains unclear. It has been hypothesized that bioactive compounds in ginger^[1] potentially ameliorate nausea and vomiting by acting as an antagonist to 5-HT₃ receptors that are involved in the process of transmitting signals to the brain via the vagus nerve, which can cause nausea. Another theory is that ginger affects and promotes gastrointestinal motility, which could reduce nausea by preventing acid reflux and vomiting. These ideas are summarized in Figure 3. Other ideas include ginger’s antioxidants or anti-inflammatory effects, ginger effects on signals within the vestibular system, or ginger’s reduction of vasopressin, which consequently reduces nausea and vomiting. Again, studies in humans have varied widely in methodology, and the mechanism of action remains undetermined.