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Feeling queasy or exhausted on top of everything else cancer throws at you can feel overwhelming. Nausea, vomiting, and fatigue are among the most common and most dreaded side effects of modern cancer care. The good news is that we now have powerful medications, smart lifestyle hacks, and team-based support to keep them under control.

What Causes Nausea During Cancer Treatment?

Everyone experiences different side effects from cancer treatment. What kinds of side effects you get and how severe they are depend on your specific treatment, cancer stage, and health issues.

Chemotherapy side effects

Chemotherapy is a catch-all phrase that means drugs that fight cancer. Traditional chemo drugs kill fast-growing cells, including cancer cells. They can also harm healthy, fast-growing cells in your gastrointestinal system or gut, causing nausea.

Health care providers give many cancer medicines through an intravenous (IV) infusion into your vein. Some medicines also come in pill form, which you take by mouth. Because they travel throughout your body, they can cause a wide range of symptoms. Targeted therapy and immunotherapy can still upset the stomach, just less often.

Radiation therapy side effects

Radiation therapy uses high-energy waves or particles to target and damage the DNA in cancer cells. This stops cancer cells from growing and dividing, which kills them. Radiation can also damage some nearby healthy tissue, leading to side effects.

Fatigue and skin problems are radiation’s most common side effects. Most people start to feel fatigued after several weeks of treatment, and this gets worse as treatment continues. When treatment ends, fatigue goes away, but this can take some time.

Skin problems often occur in the area receiving treatment. They may look and feel like bad sunburns. Your skin may look red, blistered, peeling, and itchy.

Nausea and vomiting are common side effects of radiation to the brain, head, neck, and abdomen. If you take whole-body oral radiation therapy, it can also cause these side effects.

Surgery side effects

Anesthesia and pain medicine for cancer surgery may cause nausea and vomiting. This may last 24 to 48 hours.

In people who need bone marrow or stem cell transplants, these side effects can happen because of radiation and chemotherapy before the transplant. They may also point to an infection or graft-versus-host disease.

Types of treatment-related nausea

How soon nausea may hit depends on your treatment. Ask your cancer doctor or nurse navigator to review your expectations. Cancer treatment can cause different types of nausea and vomiting, including:

• Acute — Symptoms happen within minutes of treatment and up to 24 hours afterward.
• Delayed — Symptoms start one to seven days after treatment and last several days.
• Anticipatory — Some people start to feel nauseous before their next treatment session. This is common in people who had nausea or vomited after a previous session. Sights, smells, and sounds can trigger it.
• Chronic — Symptoms are ongoing after treatment ends.

How Can I Manage Nausea During Cancer Treatment?

Cancer treatment often brings to mind images of people vomiting continuously. It’s something that often worries many people before they start treatment. The good news: Medicine has come a long way in preventing and managing cancer-related nausea and vomiting.

Medicines to manage nausea

When you get IV chemo and other cancer medicines, the infusion often includes premedication. These help prevent allergic reactions and side effects, including nausea and vomiting.

Cancer doctors often prescribe antiemetics — medications you take at home on a regular schedule to prevent nausea and vomiting. Follow the schedule and take them even if you feel fine. If you wait until you feel queasy to take them, they take longer to ease your symptoms.

Some people can have breakthrough nausea. This can happen within five days of starting anti-nausea medicine. Some people have nausea and vomiting that don’t get better with medication, also called refractory nausea.

If your medicines don’t help or stop working, call your doctor. They may increase your dose or prescribe another anti-nausea medicine.

Don’t take any over-the-counter medicines and supplements without getting the OK from your doctor. Sometimes these can make nausea worse. They may also interact with cancer medicines and make them less effective in treating your cancer.

Tips for eating and drinking

Nausea and vomiting can make eating and drinking difficult. These tips from the American Cancer Society and National Cancer Institute may help:

• Avoid greasy, fried, or spicy foods.
• Eat several small meals throughout the day. An empty stomach can make nausea worse, but so can large meals. Aim for five to six small meals instead of three large meals.
• Get enough to drink to avoid getting dehydrated. Take slow sips of water throughout the day. Avoid or limit alcohol.
• Stick to foods that are easy on the stomach and can help you feel better. These include:
  • Bland foods, such as crackers, toast, rice, plain baked potatoes, or plain yogurt.
  • Cold, clear liquids, such as apple juice, sports drinks, or room-temperature broth.
  • Sour foods like sour candy, lemons, limes, and pickles.
  • Cold or frozen treats, such as gelatin, sorbet, and popsicles. You can also suck on crushed ice.
  • Foods with ginger include ginger snap cookies, ginger ale, and ginger tea.
  • Suck on hard candy, such as lemon drops, to get rid of bad tastes. Some people suck on hard candy during chemo infusions to mask the flavor of the medicine that flushes the IV line.
• Use plastic utensils to eat or choose finger foods. Metal utensils can cause a bitter taste during some types of chemo.

If you struggle to eat, talk to a nutritionist on your cancer care team. They can help with recipes and meal planning. In extreme cases, you may also need nutritional support.

Complementary and alternative treatments

Always ask your cancer doctor or nurse what other therapies may help you control nausea and vomiting and whether they’re safe for you. Your cancer center or hospital may offer these and other holistic programs for cancer care. According to the National Cancer Institute, these may help people going through cancer treatment:

• Acupuncture and acupressure.
• Deep-breathing exercises.
• Guided imagery and hypnosis.
• Massages.
• Meditation.
• Listening to music.

When Should I Call My Doctor About Nausea from Cancer Treatment?

Uncontrolled nausea and vomiting can cause serious issues. This includes dehydration, malnutrition, electrolyte imbalances, and weight loss.

Call your doctor if you:

• Can’t keep fluids down.
• Have been vomiting for 24 hours or more.

Always tell your cancer doctor about any new symptoms you have during treatment. This helps them better manage your care and ensure nothing else is causing your nausea and other symptoms.

Editor's Note: This article was originally published on July 22, 2025, and was last reviewed on August 6, 2025.