Nausea and Vomiting

Learn to prevent and control side effects

Nausea and vomiting are different from each other, but they are often experienced together. Nausea is an unpleasant sensation of feeling the need to vomit, or throw up, and is often described as “sick to my stomach” or “queasy.” Vomiting occurs when the stomach muscles contract and push the stomach contents up through the mouth.

Nausea and vomiting are among the most often feared cancer treatment-related symptoms. Although nausea and vomiting occur in most people receiving cancer treatment, people are affected in different ways, with some people having no or only mild nausea and vomiting, and others experiencing more severe symptoms. Recent advances have led to the development of new drugs to prevent and control nausea and vomiting. These drugs are known as antiemetics.

Nausea and vomiting are unpleasant, usually cause distress (for the person with cancer as well as family members), and can limit activities. These side effects can also worsen other symptoms, such as pain, insomnia, cognitive dysfunction, fatigue and anorexia. If vomiting is not controlled and becomes severe, it can lead to dehydration, a lack of essential fluids and minerals in your body. Most importantly, severe nausea and vomiting can interrupt your cancer treatment plan. Thus, it is important to control these two symptoms.

Why do nausea and vomiting occur?

Nausea and vomiting occur as the result of a series of reactions between your stomach and your brain. These reactions start when chemotherapy or radiation damages the cells lining the inside of the stomach. The cells send signals to a vomiting center in your brain, which then sends signals to trigger nausea and vomiting. Chemotherapy may also trigger the vomiting center directly.

Who is most likely to be affected by nausea and vomiting?

Chemotherapy drugs are the most common cause of nausea and vomiting, and some drugs are more likely than others to cause these symptoms. Chemotherapy drugs have been classified according to the likelihood of causing nausea and vomiting. Drugs that cause nausea and vomiting in more than 90 percent of people are classified as having a high likelihood; drugs that cause these symptoms in 30 to 90 percent of people are classified as having a moderate likelihood. It is important to note that these likelihoods were estimated among people who did not receive treatment to prevent nausea and vomiting. The dose used, how often the drug is given, and how the drug is given (intravenously or orally) are factors in the likelihood of nausea and vomiting occurring.

Radiation therapy can also cause nausea and vomiting, and people who receive whole-body radiation or radiation to the upper abdominal area are the most likely to be affected. The likelihood of nausea and vomiting depends on which tissues are being radiated and the dose schedule of the radiation treatment. Nausea and vomiting are also side effects of many medications, especially strong pain medications, such as opioids.

There are individual differences that affect the likelihood of having nausea and vomiting. These side effects are more likely to occur in women, people younger than 50, people who are anxious, and people who have had motion sickness.

When do nausea and vomiting occur?

Nausea and vomiting related to chemotherapy are described as either acute or delayed depending on when they first occur (Table 1). Nausea and vomiting may also be described as anticipatory; this type of nausea and vomiting occurs before a dose of chemotherapy is given and usually happens in people who have had severe nausea and vomiting during a previous experience with chemotherapy.

Nausea and vomiting related to opioids usually occurs within a few hours of a dose. Over time (usually three to seven days), a person can develop tolerance to an opioid, which means that the drug will no longer cause nausea and vomiting.

Table 1. Timing of nausea and vomiting related to chemotherapy

Type of nausea and vomiting Time of first occurrence Time of worst vomiting Time of resolution
Acute Few minutes to hours after the drug is given Five to six hours Within 24 hours
Delayed More than 24 hours after drug is given 48 to 72 hours Three to seven days

How are nausea and vomiting managed?

Prevention is the key to managing nausea and vomiting, as these symptoms are easier to prevent than to control once they have started. The list of available antiemetic drugs has grown over the past few years (Table 3). Some are best for mild nausea and vomiting, and others are appropriate for more severe nausea and vomiting; some are effective for acute symptoms and others for delayed symptoms. Most antiemetic drugs can be given as either a pill or an intravenous injection. While both forms are equally effective, intravenous antiemetic drugs usually act more quickly.

Your doctor will prescribe antiemetic drugs on the basis of the chemotherapy drug or drugs you will receive. Because some of these drugs work in different ways, a combination of drugs is often the best approach, especially for people who are to receive a chemotherapy drug that has a high likelihood of causing nausea and vomiting. In these situations, antiemetic drugs are prescribed to be taken before chemotherapy starts and at specific intervals after treatment for as long as the risk of vomiting is expected. For example, an antiemetic drug is prescribed to be taken for 24 hours if the chemotherapy drug is associated with acute nausea and vomiting and for three to seven days if the drug is associated with delayed nausea and vomiting. For antiemetic drugs to be effective, it is important that they are taken “around the clock” at the prescribed intervals and not on an “as needed” basis.

Prevention of nausea and vomiting related to radiation therapy follows a similar approach. If you are to have total body radiation or radiation to the upper abdominal area, your doctor will prescribe an antiemetic drug to be taken before your scheduled treatment and for a period of time after treatment.

Because nausea and vomiting are not as common after the use of opioids as after chemotherapy or radiation therapy, antiemetic drugs are usually prescribed once nausea and vomiting have occurred. It is important to let your doctor or nurse know if you are still experiencing nausea and vomiting even after taking the drug as prescribed. This type of nausea and vomiting is known as breakthrough, and you many need a different antiemetic drug or an increased dose in order to control these symptoms.

To help further protect yourself from nausea and vomiting, you may want to supplement your antiemetic treatment with some non-drug approaches. Some people have been helped by such strategies as progressive muscle relaxation, biofeedback, guided imagery, self-hypnosis and acupuncture. Some changes to your eating habits may also be helpful:

  • Eat several small meals throughout the day rather than three big meals.
  • Try eating a light meal a few hours before your scheduled treatment.
  • Drink plenty of fluids in small amounts throughout the day.
  • Avoid unpleasant odors, as they can trigger nausea.
  • Rest after eating, but don’t lie flat.

Try bland, easy-to-digest foods like crackers. Ginger and peppermint can also help with nausea, so you may try ginger ale or peppermint tea. Avoid eating your favorite foods because after your chemotherapy is completed, it might not be your favorite food anymore if you associate it with eating it while receiving this type of treatment.

When should I talk to my doctor?

You should talk to your doctor before treatment about the potential for your planned treatment to cause nausea and vomiting. Ask your doctor what he or she can do to prevent nausea and vomiting. During your treatment, be sure to call your doctor’s office if you experience nausea and vomiting even though you are taking the antiemetic drug as prescribed.

Call your doctor immediately if you:

  • Have more than three episodes of vomiting per hour for at least three hours
  • Notice blood in the material vomited
  • Notice a coffee grounds appearance of the material vomited
  • Are unable to take more than four cups of fluid or ice chips in 24 hours or are unable to take any solid foods for more than two days
  • Cannot keep your medications down
  • Become weak or dizzy