There are three different types of chemotherapy-induced nausea and vomiting (CINV): acute, delayed and anticipatory.¹

Acute CINV occurs within the first 24 hours following chemotherapy administration, with the highest risk period occurring during the first 4 hours of treatment.²

Delayed CINV occurs more than 24 hours after chemotherapy is administered and may persist for several days.² Some experts have suggested that delayed CINV may occur as early as 16 hours after chemotherapy is initiated.²

Anticipatory CINV is defined as a conditioned (i.e., Pavlovian or learned) response³ that often occurs before starting a new chemotherapy cycle in patients who have experienced uncontrolled CINV with prior treatments.³ In the proposed conditioned-response model for anticipatory CINV, nausea with or without vomiting is a response to conditioned neutral stimuli such as the smells, sights and sounds of the clinic, which signal the initiation of an unconditioned stimulus (the infusion of chemotherapy drugs).³

The following circumstances may help identify which patients are more likely to experience CINV⁴:

• Being younger than 50 years old
• The severity of CINV after the last chemotherapy
• Feeling warm or hot after the last chemotherapy
• A history of motion sickness
• Feeling dizzy or lightheaded after chemotherapy
• Sweating after the last chemotherapy session
• Experiencing weakness after the last chemotherapy session
• Having a high level of anxiety
• The type of chemotherapy (some are more likely to cause CINV)

It also should be noted that radiation therapy, surgery and a variety of medications may induce nausea and vomiting in patients.³ Additionally, patients with advanced cancer may experience chronic nausea and vomiting related to tumor progression and not necessarily associated with treatment.³