I found the following informative explanation of the different phases of chemotherapy induced nausea and vomiting very helpful (per my emphasis in bold). Hopefully it will help those of us currently experiencing this common distressing side effect from treatment to know of the different phases and if you live in the States, you may even be able to access Emend via injection - very handy when you can't get anti-emetic tablets down and want fast relief!
"Chemotherapy-induced nausea and vomiting falls into two major categories—the acute phase, which occurs within 24 hours after administration of chemotherapy; and the delayed phase, which typically starts at least 24 hours after administration. Up to about 25% of patients who have received prior chemotherapy can also experience anticipatory chemotherapy-induced nausea and vomiting, a result of classic conditioning from a prior nausea or vomiting experience that typically occurs within 12 hours prior to administration of chemotherapy.
Chemotherapy-induced nausea and vomiting is a major issue for many patients receiving chemotherapy to treat their cancer. According to some studies, about 40% of patients receiving a new chemotherapy regimen develop acute nausea and vomiting, and as many as 60% of patients experience delayed symptoms."
And here's a previous post about another related FDA approval for a new anti-nausea drug: