Nausea and Vomiting

Last updated: January 2025 | Medical Reviewer: Oncol.net Editorial Board

Overview

Nausea and vomiting are common side effects of cancer treatment, particularly chemotherapy and radiation therapy. Nausea is the unpleasant sensation of needing to vomit, while vomiting (emesis) is the forceful expulsion of stomach contents. These symptoms can significantly impact quality of life, nutrition, and ability to continue cancer treatment.

The incidence and severity of nausea and vomiting depend heavily on the specific cancer treatment being received. Some chemotherapy drugs are highly emetogenic (cause vomiting in >90% of patients without preventive medication), while others rarely cause these symptoms. Modern antiemetic medications have dramatically improved control of these side effects over the past 30 years.

Causes of Nausea and Vomiting

Chemotherapy-Induced Nausea and Vomiting (CINV)

Different chemotherapy drugs have varying levels of emetogenic potential:

Timing of CINV

• Acute (0-24 hours after chemotherapy): Most common, typically peaks 4-6 hours after treatment
• Delayed (>24 hours after chemotherapy): Occurs 2-5 days after treatment, common with cisplatin, carboplatin, cyclophosphamide, doxorubicin
• Anticipatory: Triggered by sights, sounds, or smells associated with treatment; occurs BEFORE chemotherapy begins due to conditioning from previous experiences
• Breakthrough: Occurs despite preventive medication, requiring rescue medication
• Refractory: Occurs in subsequent cycles when prophylactic and rescue regimens have failed in earlier cycles

Other Causes

• Radiation therapy: Especially to abdomen, pelvis, or brain; higher doses and larger treatment areas increase risk
• Cancer itself:
  • Brain tumors or brain metastases (increased intracranial pressure)
  • Gastrointestinal cancers causing obstruction
  • Liver metastases
  • Hypercalcemia (high blood calcium)
• Medications: Opioid pain medications, antibiotics, iron supplements
• Other factors:
  • Constipation or bowel obstruction
  • Gastroparesis (delayed stomach emptying)
  • Infection
  • Electrolyte imbalances
  • Anxiety and stress
  • Uncontrolled pain

Risk Factors for CINV

Patient-Related Risk Factors

• Age: Younger patients (<50 years) have higher risk
• Gender: Women have 2-3 times higher risk than men
• History of motion sickness or morning sickness: Increased risk
• History of CINV in previous cycles: Strong predictor of future episodes
• Low chronic alcohol consumption: Patients who drink heavily (>5 drinks/day) have LOWER risk (mechanism unclear)
• Anxiety and expectation of nausea: Increases risk, especially anticipatory nausea

Treatment-Related Risk Factors

• Emetogenic potential of chemotherapy regimen (most important factor)
• Dose and schedule of chemotherapy
• Route of administration (IV vs oral)
• Combination chemotherapy (additive effects)
• Concurrent radiation therapy

Prevention Strategies

Antiemetic Medications (Anti-Nausea Drugs)

Multiple classes of medications are used, often in combination for high-risk regimens:

5-HT3 Receptor Antagonists ("Setrons")

• Most commonly prescribed antiemetics
• Examples: ondansetron (Zofran), granisetron (Kytril), palonosetron (Aloxi)
• How they work: Block serotonin receptors in gut and brain that trigger vomiting
• When given: Before chemotherapy (IV or oral), then as needed after treatment
• Most effective for: Acute CINV (first 24 hours)
• Side effects: Headache (common), constipation, QT prolongation (heart rhythm - rare)
• Palonosetron: Longer-acting (half-life 40 hours), may help with delayed nausea, given as single IV dose

NK1 Receptor Antagonists

• Examples: aprepitant (Emend), rolapitant (Varubi), fosaprepitant (Emend IV)
• How they work: Block substance P in brain's vomiting center
• When given: Before chemotherapy, with additional doses on days 2-3
• Most effective for: Both acute and delayed CINV
• Essential for: High and moderate emetogenic chemotherapy
• Side effects: Fatigue, hiccups, mild elevation of liver enzymes
• Drug interactions: Affects many medications metabolized by CYP3A4 (including dexamethasone - dose adjustment needed)

Corticosteroids

• Example: dexamethasone (Decadron)
• How they work: Anti-inflammatory effects, exact antiemetic mechanism unknown
• When given: Before and after chemotherapy (days 1-4 typically)
• Most effective for: Both acute and delayed CINV, synergistic with other antiemetics
• Side effects: Insomnia, increased appetite, elevated blood sugar, mood changes, agitation
• Dose reduction needed when given with NK1 antagonists

Dopamine Receptor Antagonists

• Examples:
  • Metoclopramide (Reglan): Also promotes gastric emptying
  • Prochlorperazine (Compazine)
  • Promethazine (Phenergan): Also has antihistamine properties
• How they work: Block dopamine receptors in brain's chemoreceptor trigger zone
• When given: As breakthrough or rescue medication, less effective as prevention
• Side effects: Drowsiness, restlessness, dystonia (muscle spasms), tardive dyskinesia (with long-term use)

Olanzapine (Zyprexa)

• Atypical antipsychotic with potent antiemetic properties
• How it works: Blocks multiple neurotransmitter receptors (dopamine, serotonin, histamine)
• When given: 5-10 mg daily for 3-4 days starting before chemotherapy
• Highly effective for: Delayed and breakthrough CINV, especially with high emetogenic regimens
• Increasingly used as first-line prevention for highly emetogenic chemotherapy
• Side effects: Sedation (significant in some patients), increased appetite, weight gain, elevated blood sugar

Benzodiazepines

• Examples: lorazepam (Ativan), alprazolam (Xanax)
• How they work: Reduce anxiety, have mild antiemetic effects
• When given: Before chemotherapy and as needed
• Most effective for: Anticipatory nausea, anxiety-related nausea
• Side effects: Drowsiness, amnesia, dependency with long-term use

Cannabinoids (Medical Marijuana)

• Examples: dronabinol (Marinol), nabilone (Cesamet), CBD/THC products
• How they work: Affect cannabinoid receptors in brain
• Effectiveness: Moderate antiemetic effect, may help appetite
• When used: Breakthrough/refractory nausea, not first-line
• Side effects: Drowsiness, dizziness, mood changes, dry mouth, increased appetite
• Legal status varies by state

Standard Prevention Regimens by Emetogenic Risk

High Emetogenic Chemotherapy (e.g., Cisplatin, AC)

• Day 1: NK1 antagonist + 5-HT3 antagonist + dexamethasone + olanzapine
• Days 2-4: NK1 antagonist (if aprepitant) + dexamethasone + olanzapine

Moderate Emetogenic Chemotherapy (e.g., Carboplatin, Oxaliplatin)

• Day 1: NK1 antagonist + 5-HT3 antagonist + dexamethasone
• Days 2-3: NK1 antagonist (if aprepitant) + dexamethasone OR metoclopramide OR olanzapine

Low Emetogenic Chemotherapy

• Day 1: 5-HT3 antagonist OR metoclopramide OR dexamethasone (one agent)
• Days 2+: As needed for breakthrough symptoms

Minimal Emetogenic Chemotherapy

• No routine prophylaxis needed
• Rescue medication available if needed

Managing Nausea and Vomiting

Breakthrough Nausea

If nausea occurs despite preventive medication:

• Take rescue medication as prescribed (don't wait for vomiting to start)
• Common rescue options:
  • Additional dose of 5-HT3 antagonist (ondansetron 8 mg every 8 hours as needed)
  • Metoclopramide 10-20 mg every 6-8 hours
  • Prochlorperazine 10 mg every 6-8 hours (oral or suppository)
  • Olanzapine 5 mg daily if not already prescribed
• Notify your oncology team if rescue medications are not effective - regimen adjustment needed for next cycle

Dietary Modifications

• Small, frequent meals: Eat 5-6 small meals instead of 3 large ones
• Bland, easy-to-digest foods:
  • Dry crackers, toast, pretzels
  • Plain rice, pasta, potatoes
  • Bananas, applesauce
  • Chicken broth, clear soups
  • Gelatin, popsicles
• Avoid:
  • Greasy, fried, or fatty foods (slow stomach emptying)
  • Very sweet or very spicy foods
  • Foods with strong odors
  • Large meals that make you feel overly full
• Cold or room temperature foods: Often better tolerated than hot foods (less odor)
• Sip liquids slowly throughout the day: Avoid drinking large amounts at once
• Don't force yourself to eat favorite foods when nauseous: May develop food aversions

Timing and Eating Strategies

• Eat lightly before chemotherapy (empty stomach may worsen nausea, but overly full stomach also problematic)
• Don't eat your favorite foods right before chemotherapy (risk of developing permanent aversion)
• Eat when you feel best (many patients feel better in morning)
• Sit upright or reclined (not lying flat) for 1-2 hours after eating
• Eat slowly and chew thoroughly
• Rest after eating, but don't lie completely flat

Hydration

• Sip clear liquids throughout the day (water, ginger ale, sports drinks, broth)
• Take small sips every 15-30 minutes rather than drinking large amounts at once
• Try cold beverages or ice chips if they're more appealing
• Aim for at least 8-10 cups (64-80 oz) of fluid daily unless restricted
• Monitor for dehydration: dark urine, dizziness, dry mouth, decreased urination

Environmental and Behavioral Strategies

• Fresh air: Open windows, use fans, spend time outdoors
• Avoid strong smells:
  • Cooking odors (have someone else cook, or eat cold foods)
  • Perfumes, colognes, scented products
  • Smoke
• Distraction: Music, TV, reading, meditation, gentle activities
• Relaxation techniques:
  • Deep breathing exercises
  • Progressive muscle relaxation
  • Guided imagery
  • Meditation or mindfulness
• Wear loose, comfortable clothing: Tight clothing around waist can worsen nausea
• Get adequate rest: Fatigue can worsen nausea

Alternative and Complementary Approaches

• Ginger: Natural antiemetic properties
  • Forms: ginger tea, ginger ale (with real ginger), ginger candies, ginger capsules (250-500 mg 3-4 times daily)
  • Evidence: Moderate benefit, especially for mild nausea
  • Generally safe, minimal side effects
• Acupressure/Acupuncture:
  • P6 (Neiguan) point on inner wrist (three finger-widths below wrist crease between tendons)
  • Wristbands (Sea-Bands) apply pressure to this point
  • Some evidence of benefit, especially for mild-moderate nausea
  • No side effects, low cost
• Aromatherapy:
  • Peppermint or ginger essential oils
  • Inhale or apply to wrists/temples
  • Limited evidence but may provide comfort
• Hypnosis: May help with anticipatory nausea
• Music therapy: Distraction and relaxation

Complications of Severe Nausea/Vomiting

Dehydration and Electrolyte Imbalances

• Signs: Dizziness, dark urine, decreased urination, dry mouth, weakness
• Can lead to kidney problems
• May require IV fluids

Malnutrition and Weight Loss

• Difficulty maintaining adequate caloric intake
• Weight loss can delay cancer treatment
• May require nutritional supplementation or feeding tube in severe cases

Esophageal Tears (Mallory-Weiss Tears)

• Rare but serious complication of forceful vomiting
• Symptoms: Vomiting blood or coffee-ground material, chest/abdominal pain
• Requires immediate medical attention

Aspiration

• Inhaling vomit into lungs
• Can cause pneumonia
• Risk increased when lying flat or sedated

Treatment Delays or Discontinuation

• Severe, uncontrolled nausea/vomiting may necessitate dose reductions or treatment delays
• Can impact cancer outcomes
• Work with team to optimize antiemetic regimen to continue treatment

Anticipatory Nausea and Vomiting

What is Anticipatory Nausea?

A conditioned response where nausea/vomiting occurs BEFORE chemotherapy, triggered by sights, sounds, smells, or thoughts associated with treatment. Develops in 20-30% of patients, usually after experiencing nausea/vomiting in previous cycles.

Triggers

• Entering the infusion center
• Seeing the IV pole or infusion bags
• Smell of alcohol swabs or antiseptics
• Thoughts about upcoming treatment
• Anxiety before treatment day

Prevention and Management

• Best prevention: Excellent control of CINV in first few cycles (once conditioning occurs, harder to reverse)
• Benzodiazepines: Lorazepam or alprazolam before treatment reduces anxiety and nausea
• Behavioral interventions:
  • Progressive muscle relaxation
  • Guided imagery
  • Systematic desensitization
  • Hypnosis
  • Cognitive behavioral therapy
• Distraction techniques: Music, movies, conversation during infusion
• Avoid triggers when possible: Different route to infusion center, focusing on pleasant thoughts

Radiation-Induced Nausea and Vomiting

Risk Factors

• Treatment site: Highest risk with upper abdomen, total body irradiation, brain
• Dose per fraction and total dose
• Field size (larger fields = higher risk)

Prevention

• High-risk radiation: 5-HT3 antagonist before each fraction + rescue medication as needed
• Moderate-risk: 5-HT3 antagonist or metoclopramide before treatment
• Low-risk: Rescue medication available as needed

Management

• Similar dietary and behavioral strategies as CINV
• May worsen over course of radiation (cumulative effect)
• Usually resolves within 1-2 weeks after completing radiation

Frequently Asked Questions

How long will nausea last after chemotherapy?

Timing varies by regimen. Acute nausea typically lasts 24-48 hours after chemotherapy. Delayed nausea can last 2-5 days, sometimes up to 7 days with certain regimens like cisplatin. With appropriate antiemetic medications, many patients experience minimal nausea. If symptoms persist beyond expected timeframe or worsen over multiple cycles, discuss with your oncology team.

Can I take more than one anti-nausea medication at the same time?

Yes, absolutely. Different antiemetic medications work through different mechanisms, so combining them is often more effective than using a single agent. In fact, standard prevention for high-risk chemotherapy involves 3-4 different antiemetics given together (NK1 antagonist + 5-HT3 antagonist + steroid + olanzapine). Always follow your prescribed regimen and check with your team before adding additional medications.

Why do I need to take anti-nausea medication even if I don't feel sick?

Prevention is far more effective than treatment once nausea starts. Chemotherapy-induced nausea follows predictable patterns based on the drugs used. Taking preventive medication as scheduled, even when you feel fine, blocks the nausea before it develops. Waiting until you feel sick makes it much harder to control symptoms.

Will ginger really help with nausea?

Yes, ginger has mild to moderate antiemetic effects and is supported by scientific evidence. It's most helpful for mild nausea and can be a nice complement to prescription medications. However, ginger alone is not sufficient for chemotherapy-induced nausea - you still need your prescribed antiemetics. Forms of ginger include tea, candies, capsules (250-500 mg 3-4 times daily), or real ginger ale (not artificially flavored).

Is it safe to use marijuana for nausea?

Medical marijuana (cannabinoids) can help with nausea, particularly breakthrough or refractory nausea not controlled by other medications. Prescription forms (dronabinol, nabilone) are FDA-approved. Effectiveness is moderate compared to standard antiemetics. Side effects include drowsiness, dizziness, and mood changes. Legal status varies by state. Discuss with your oncology team if you're interested in trying cannabinoids - they can help you navigate options and legality in your area.

Why does everything smell bad during chemotherapy?

Chemotherapy can alter your sense of smell and taste, making previously pleasant odors unpleasant or overwhelming. This is a direct effect of chemotherapy on sensory nerves and brain processing. Additionally, nausea heightens sensitivity to smells. Strategies: avoid strong-smelling foods, use unscented products, keep environment well-ventilated, eat cold foods (less odor), and have someone else do the cooking.

Can anxiety make my nausea worse?

Yes, definitely. Anxiety activates the same brain pathways involved in nausea and vomiting. Many patients develop anticipatory nausea due to anxiety about treatment. Managing anxiety with relaxation techniques, counseling, or anti-anxiety medications (benzodiazepines) can significantly reduce nausea. Let your team know if anxiety is a significant issue - it's treatable.

What if I'm vomiting so much I can't keep my medications down?

Contact your oncology team immediately. You may need IV antiemetics and fluids. Options include: suppositories (prochlorperazine), sublingual or orally dissolving tablets (ondansetron ODT), patches (scopolamine), or IV medications administered in the clinic or hospital. Severe vomiting preventing oral medication intake requires urgent medical attention.

Will I have nausea every single day during treatment?

Not necessarily. Most patients have nausea primarily in the days immediately following chemotherapy administration (days 1-5), then feel better until the next cycle. The pattern depends on your specific chemotherapy regimen. Daily oral chemotherapy may cause more continuous low-level nausea. Many patients have "good days" and "bad days" throughout each cycle.

Can I develop tolerance to anti-nausea medications?

Generally, no. Unlike pain medications, tolerance to antiemetics is uncommon. If medications become less effective over multiple cycles, it's more likely due to anticipatory conditioning, cumulative chemotherapy effects, or inadequate dosing rather than true tolerance. Your regimen can be adjusted - don't suffer unnecessarily.

Sources and References

• National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines: Antiemesis
• American Society of Clinical Oncology (ASCO) Antiemetic Guidelines
• Multinational Association of Supportive Care in Cancer (MASCC) Guidelines
• Hesketh PJ. Chemotherapy-Induced Nausea and Vomiting. New England Journal of Medicine. 2008
• Navari RM, Aapro M. Antiemetic Prophylaxis for Chemotherapy-Induced Nausea and Vomiting. NEJM. 2016