Causes

Chemotherapy and radiation therapy are the most common causes of nausea and vomiting in patients being treated for cancer.

Nausea is controlled by a part of the central nervous system that controls involuntary body functions (like the heart beating). Vomiting is a reflex controlled by a vomiting center in the brain. Vomiting can be triggered by smell, taste, anxiety, pain, motion, poor blood flow, irritation, or changes in the body caused by inflammation.

The most common causes of nausea and vomiting are:

• Chemotherapy.
• Radiation therapy to the gastrointestinal (GI) tract, liver, or brain.

Many factors increase the risk for nausea and vomiting.

Nausea and vomiting are more likely if the patient:

• Had severe or frequent periods of nausea and vomiting after past chemotherapy sessions.
• Is female.
• Is younger than 50 years.
• Has a fluid and/or electrolyte imbalance (dehydration, too much calcium in the blood, or too much fluid in the body's tissues).
• Has a tumor in the GI tract, liver, or brain.
• Has constipation.
• Is receiving certain drugs, such as opioids (pain medicine).
• Has an infection or blood poisoning.
• Has kidney disease.
• Has anxiety.

Anticipatory Nausea and Vomiting

Anticipatory nausea and vomiting may occur after several treatment sessions.

Anticipatory nausea and vomiting occur in some patients after they have had several courses of treatment. This is caused by triggers, such as odors in the therapy room. For example, a person who begins chemotherapy and smells an alcohol swab at the same time may later have nausea and vomiting at the smell of alcohol alone. The more chemotherapy sessions a patient has, the more likely it is that anticipatory nausea and vomiting will develop. The following may make anticipatory nausea and vomiting more likely:

• Being younger than 50 years.
• Being female.
• Having any of the following, after the last chemotherapy session:
  • Nausea and vomiting.
  • Feeling warm or hot.
  • Feeling weak.
  • Sweating.
  • Feeling dizzy or lightheaded.
• A history of motion sickness.
• Having a high level of anxiety.
• Certain types of chemotherapy (some are more likely to cause nausea and vomiting).
• Having morning sickness during pregnancy.

Treatment of anticipatory nausea and vomiting should begin early.

Treatment of anticipatory nausea and vomiting is more likely to work when symptoms are treated early. Although antinausea drugs do not seem to help, the following types of treatment may decrease symptoms:

• Muscle relaxation with guided imagery.
• Hypnosis.
• Behavior changing methods.
• Biofeedback.
• Distraction (such as playing video games).

Psychologists and other mental health professional with special training in these treatments can often help patients with anticipatory nausea and vomiting.