The risk of chemotherapy-induced nausea and vomiting varies based on the type of treatment received as well as several outside factors. Some types of chemotherapy are more prone to causing nausea and vomiting than others. Some chemotheraputic agents may not cause nausea and vomiting on their own, but may when used in combination with other agents.[6] Regimens that are linked to a high incidence (90% or higher) of nausea and vomiting are referred to as "highly emetogenic chemotherapy", and those causing a moderate incidence (30–90%) of nausea and vomiting are referred to as "moderately emetogenic chemotherapy".[7]