Researchers do not know exactly why some chemotherapy drugs cause nausea and vomiting. They believe there are several ways that this can happen. Some drugs may affect the parts of your spinal cord or nervous system that trigger nausea and vomiting. Some drugs may cause nausea and vomiting by irritating the lining of your digestive system. Sometimes, if you had nausea when you had chemotherapy before, your brain remembers this and expects nausea when you have chemotherapy again.

Chemotherapy drugs are ranked according to how often they cause nausea and vomiting. Some cause very little of those side effects. Also, some people are more likely than others to get sick. Your doctor will consider many things about you, your treatment, and your cancer to decide if you are likely to feel sick.

Your risk of having nausea and vomiting

Whether you have nausea and vomiting may depend on:

• What types of chemotherapy drugs you get. Some of these drugs are more likely to cause nausea and vomiting than others.
• How large a dose you get. Higher doses are more likely to cause nausea and vomiting.
• When and how often you get chemotherapy. If the time between treatments is short, your body has less time to recover from the nausea and vomiting before you get your next dose.
• How the drugs are given. A drug that is given through your vein (IV) may cause nausea and vomiting sooner than a pill that is swallowed, because your body will absorb the IV drug faster.
• Individual differences. Not every person reacts the same to the same medicine.
• The antinausea medicine you are taking. If it isn't working for you, you may need to try a different one.

You may feel sick shortly after your chemotherapy treatment begins. Or you may not feel sick until a day or two later. You may not feel sick at all. As soon as you start to feel sick, tell your doctor.

Many people start feeling sick before a treatment session even begins. This is called anticipatory nausea and vomiting. Any little thing—the smell of an alcohol swab, the sight of a nurse's uniform, the sounds of the treatment room—may trigger nausea. This usually doesn't happen until after the third or fourth treatment session. Learning how to control anticipatory nausea and vomiting is important, because it can make nausea and vomiting more severe when the chemotherapy actually starts.

People who feel good are better able to fight their cancer and have happier lives. Your body needs to be able to rest, to refuel, and to cope with the stresses of cancer and its treatment.

If untreated, nausea and vomiting can make you feel:

• Depressed.
• Unable to cope.
• Tired.
• Stressed.
• Unable to sleep.
• Worried.
• Angry.
• Uninterested in food.
• Dehydrated.

Controlling your nausea and vomiting can help you to:

• Be active.
• Sleep.
• Cope better with your cancer and its treatment.
• Enjoy family and friends.
• Eat with pleasure.

The best way to control nausea and vomiting is to begin treatment for it before you start chemotherapy. Talk to your doctor about your treatment plan. Find out if the cancer drug you'll receive is likely to make you sick. Ask your doctor what medicines are available to prevent nausea and vomiting. Talk about your concerns, no matter how small. The more you know about your treatment, the more you will feel in control and the easier it will be to talk about it with your doctors and nurses.

Antinausea drugs

Reference Antinausea drugs are usually taken on a regular daily schedule for as long as chemotherapy lasts. Sometimes you may be asked to take the antinausea drug "only as needed." You may be given more than one kind of antinausea drug. Drugs to relieve your nausea include ondansetron (Zofran) and lorazepam (Ativan).

Antinausea drugs can be given as pills you swallow, through your vein (Reference IV Opens New Window), or as shots. Some drugs are available as suppositories, as capsules that melt in your mouth, or as a patch that is taped to your skin.

Be sure to follow your doctor's instructions for taking your antinausea medicines and to report back about how well they are working.

If you have nausea and vomiting after chemotherapy in spite of taking antinausea drugs, tell your doctor immediately. A different antinausea drug may be the answer. Or your chemotherapy drug may need to be changed.

Medical marijuana

Reference Marijuana, either in its natural form or as a synthetic drug, has been shown to ease the nausea and vomiting caused by chemotherapy. Although it worked better than many of the antinausea drugs available in the past, it doesn't seem to work as well as other medicines available today. And marijuana can cause unpleasant side effects including dry mouth, low blood pressure, and dizziness, especially in older people or people who haven't used it before. Also, the legality of marijuana for medical use is still a question in many countries.

Some doctors still use the synthetic form of marijuana to treat nausea and vomiting. These drugs have not been shown to work as well as other drugs now available, but they may be helpful for certain people.^{Reference 1}

Complementary therapy

Although drugs are the main way to treat nausea and vomiting, there are other treatments that have been shown to work well.^{Reference 1} They involve the help of a qualified therapist who can teach you to use your mind and body to control nausea and vomiting. These techniques help stop anticipatory nausea and vomiting. They work by relaxing you, distracting your attention, helping you feel in control, and making you feel less helpless. These treatments include:

• Reference Biofeedback. Biofeedback uses the mind to control a body function that the body normally regulates on its own, such as skin temperature, muscle tension, or heart rate.
• Reference Guided imagery. This is a series of thoughts and suggestions that direct your imagination toward a relaxed, focused state. This technique can help you mentally block the nausea and vomiting.
• Reference Distraction Opens New Window. For example, kids getting chemotherapy may use a video game to help keep their mind off what is happening. This may also help mentally block the nausea and vomiting.
• Reference Progressive muscle relaxation. This is a technique in which you learn to relax by tensing and then releasing different groups of muscles, one at a time.
• Reference Self-hypnosis. A therapist can teach you to hypnotize yourself. Some people are able to learn from books.

Acupuncture

Some studies have shown that Reference acupuncture is an effective treatment for nausea and vomiting caused by chemotherapy.^{Reference 2} Your doctor may refer you to a qualified acupuncturist.

You can also try Reference acupressure. Constant pressure on the P6 point is used to prevent or reduce nausea. The P6 point is on the inner side of your arm, in line with your middle finger. It is close to your wrist, one-sixth of the distance between your wrist and elbow. You can press on your arm with a thumb or finger or try wearing wristbands (such as Sea-Bands) that press a plastic disc on the P6 point on each arm.

Nutrition

Eating well may seem to be an odd way to treat nausea and vomiting, but it's very important. As a cancer patient, you need nutritious foods to help you feel better, keep up your strength and energy, keep up your weight, and keep up your ability to fight infection and recover as quickly as possible.

Here are some tips for eating well during chemotherapy:

• Eat small, frequent meals or snacks. Treat yourself by choosing the foods you like best.
• Make the most of the days when your appetite is good.
• Ask friends and family for help with shopping and preparing meals. Consider having meals delivered to your home or have lunch at a community or senior center.
• Nutritional supplements are convenient and can help you get the extra calories and protein you need. Try a variety to find out which ones work best. Your doctor, nurse, or dietitian can help and may have samples for you to try.
• Is there a time of day when you are able to eat more? Many people find that breakfast time is best. Try eating more during that time of day when you can.
• Don't force yourself to eat when you are nauseated.
• Eat food cold or at room temperature.
• Keep your mouth clean, and brush your teeth after vomiting.
• Have fresh air with a fan or an open window.
• Limit sounds, sights, and smells that make you feel sick.
• When you don't feel like eating your normal foods, try apple or grape juice, weak teas, clear broths, dry toast, cooked cereal, and gelatin desserts. Avoid citrus juices and lemonade.
• Try ginger, such as candied ginger or ginger tea. Real ginger—not ginger flavoring—helps to reduce nausea.
• Eat a light meal or snack before your chemotherapy appointment so that you have something in your stomach.
• If your chemotherapy is the kind that takes several hours rather than a few minutes, bring a light meal or snacks with you. Your treatment center should have a refrigerator and microwave available for your use.

It's important to tell your doctors or nurses when you feel any nausea. Sometimes people worry about bothering the doctor or nurse. Sometimes they think there is nothing that can be done, so it is not worth bringing up. Speak up about your fears and about any nausea you are feeling, no matter how slight. You may need a different medicine for nausea a few days after chemotherapy than the one you used right afterward.

To help you and your health care team deal with any nausea and vomiting, you may want to keep track of how you feel. You can use a Reference symptoms diary to write down how you are feeling. Take your diary with you whenever you visit your doctor.

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