Anticipatory symptoms may also appear in patients who are receiving radiation therapy. Acute nausea and vomiting usually occur within 24 hours after chemotherapy has begun. Delayed, or late, nausea and vomiting occur more than 24 hours after chemotherapy and can last several days. Causes Nausea and vomiting are controlled by the central nervous system. Nausea is controlled by a part of the nervous system that controls involuntary bodily functions.
Vomiting is a reflex controlled by a vomiting center in the brain.
Vomiting can be stimulated by various triggers, such as smell, taste, mental upset, pain, motion, changes in the body caused by inflammation, poor blood flow, or irritation. For example, a person who begins chemotherapy and smells an alcohol swab at the same time, may later experience nausea and vomiting at the smell of alcohol alone. Smells are more likely to trigger nausea, while thoughts of the treatment will trigger vomiting. Usually, the pattern of anticipatory nausea and vomiting is set by the fourth or fifth course of treatment. Certain factors may help predict which patients are more likely to experience anticipatory nausea and vomiting.