If you experience nausea and vomiting while undergoing cancer treatment, you may find it taking a toll on your quality of life. Uncontrolled nausea and vomiting can lead to excessive loss of fluids from your body, resulting in dehydration. This can contribute to additional fatigue and may add to the stress of what's already an emotionally trying time.

Not everyone who has cancer will experience nausea and vomiting, but for those who do, treatment is available. Understand what causes nausea and vomiting and what you and your doctor can do to reduce or eliminate them. Work with your doctor to lessen their impact on your life.

Nausea and vomiting are coordinated by mechanisms within your brain and spinal cord (central nervous system). Nausea and vomiting associated with cancer can have numerous causes, including certain chemotherapy drugs and radiation to the gastrointestinal tract, liver or brain. Tumors also can cause nausea and vomiting, particularly if they affect the inner ear, gastrointestinal tract, liver or brain. Anxiety about beginning treatment can make you feel nauseous. Dehydration and constipation also can cause nausea and vomiting during treatment.

In addition, if you expect that your treatment will cause nausea and vomiting, there's a chance that it will. Your mind can become so convinced that nausea and vomiting will occur that it does occur. This might happen if you think, like many people do, that all cancer treatments cause these side effects, which isn't true. Your doctor can tell you specifically whether the treatment you'll receive is likely to cause nausea and vomiting.

Cancer-related nausea and vomiting is divided into categories. Your doctor uses these categories when deciding how to treat you for nausea and vomiting. The categories include:

• Anticipatory. This type of nausea and vomiting occurs before the start of a new chemotherapy cycle. If previous cycles of chemotherapy caused nausea and vomiting, you may anticipate these side effects with your next cycle of treatment and, consequently, have a reaction even before the treatment begins. For instance, sometimes the smell of the outpatient chemotherapy unit can trigger nausea because your mind associates that smell with the nausea you had previously. This is becoming less common as treatments are becoming more effective in preventing anticipatory nausea and vomiting.
• Acute-onset. Acute-onset nausea and vomiting occurs within a day of chemotherapy treatment. Symptoms are typically the most severe several hours after treatment.
• Delayed-onset. This type of nausea and vomiting begins more than a day after a chemotherapy treatment. It's more likely to occur if you're receiving high-dose chemotherapy or have previously had acute-onset nausea and vomiting.
• Chronic. Chronic nausea and vomiting occur in those who have advanced cancer. Multiple factors may play a role, for example, constipation, dehydration, brain or gastrointestinal cancers, and the use of certain medications, such as opioids or antidepressants.

Nausea and vomiting won't occur in everyone who has cancer or who's undergoing cancer treatment. But it does affect about half of those treated. Certain chemotherapy drugs are more likely to cause nausea and vomiting than are others, including:

• Carmustine (BiCNU)
• Cisplatin (Platinol)
• Cyclophosphamide (Cytoxan, Neosar)
• Dacarbazine (DTIC-Dome)
• Streptozocin (Zanosar)
• Mechlorethamine (Mustargen)

Not everyone reacts to treatment in the same way. Certain factors may make you more vulnerable to treatment-related nausea and vomiting. You may be more vulnerable if one or more of the following apply to you:

• You're a woman.
• You're younger than 50.
• You've experienced nausea and vomiting with previous treatments or you have a history of motion sickness.
• You have a high level of anxiety.

Depending on your specific risk of nausea and vomiting and on the type of treatment you'll receive, your doctor might prescribe anti-nausea medication before you begin treatment. This can help prevent nausea and vomiting from happening. In other cases, your doctor may prescribe anti-nausea drugs after you find that your treatment is causing these side effects.

Anti-nausea (anti-emetic) drugs can greatly reduce the impact of nausea and vomiting. These drugs, given alone or in combination — and typically taken orally — are primarily effective at treating acute-onset nausea and vomiting. Anti-nausea medications are typically given before treatment and on a scheduled basis for several hours or days after treatment.

Your doctor determines which anti-nausea medication(s) to use based on your specific situation, for example, what type of chemotherapy medications you're receiving. If an anti-nausea medication doesn't work for you, tell your doctor. Other medications may be available.

If your chemotherapy typically causes more nausea and vomiting, commonly used anti-nausea medications include:

• Aprepitant (Emend)
• Dolasetron (Anzemet)
• Dexamethasone (Decadron)
• Granisetron (Kytril)
• Metoclopramide (Reglan)
• Prochlorperazine (Compazine, Compro)
• Palonosetron (Aloxi)
• Ondansetron (Zofran)

The most effective treatment for anticipatory nausea and vomiting is to prevent acute nausea from occurring in the first place. If you've experienced nausea and vomiting during previous chemotherapy cycles, your risk of experiencing these in anticipation of your next round of treatment is increased. Talk to your doctor about stopping nausea and vomiting before they start. If the anti-nausea medications you took during your first chemotherapy treatment didn't work well, bring this up to your doctor. He or she can make adjustments to your anti-nausea medication in the future.

If anti-nausea medications don't provide relief from anticipatory nausea and vomiting, anti-anxiety medications, such as lorazepam (Ativan), may help. In addition, you might try other strategies, such as progressive muscle relaxation, acupuncture and acupressure.

Medications used to treat chronic nausea and vomiting in advanced cancer may vary, depending on what's causing the symptoms. For example, your doctor may recommend using laxatives if constipation seems to be causing the problem.

Other strategies to help further reduce nausea and vomiting exist. For example:

• Eat small meals. Stagger small meals throughout the day rather than eating fewer, larger meals. If possible, don't skip meals. Eating a light meal a few hours before treatment also may help.
• Eat what appeals to you. It's best, however, to avoid foods that are sweet, fried or fatty. In addition, cool foods may give off less-bothersome odors. Cook and freeze meals in advance of treatment to avoid cooking when you're not feeling well. Or have someone else cook for you.
• Drink lots of fluids. Try cool beverages such as water, unsweetened fruit juices, tea or ginger ale that's lost its carbonation. It may help to drink small amounts throughout the day, rather than larger amounts less frequently.
• Avoid unpleasant smells. Limit exposure to unpleasant smells. Fresh air may help.
• Make yourself comfortable. After eating, rest, but don't lie flat for a couple of hours. Try wearing loosefitting clothing and keeping yourself distracted.
• Use relaxation techniques. Examples include meditation and deep breathing.

You may choose to combine these techniques with medication to ease any nausea and vomiting you might experience.