Vomiting During Chemotherapy: When to Call Your Doctor

Vomiting is one of the most common chemotherapy side effects, affecting up to 80% of people depending on the drugs used and individual factors. While mild nausea and occasional vomiting can be managed at home, certain warning signs mean you should contact your oncology team right away. Knowing when to call your doctor can help prevent dehydration, nutritional problems, and other serious complications.

Why Chemotherapy Causes Vomiting

Chemotherapy drugs can trigger the brain’s “vomiting center” by:

• Stimulating serotonin receptors in the gut
• Activating substance P and the neurokinin-1 (NK1) pathway
• Affecting the chemoreceptor trigger zone in the brain
• Lowering stomach emptying, leading to a full, queasy feeling

Risk factors that increase your chance of chemo-induced vomiting include:

• High-emetic-risk chemotherapy regimens (e.g., cisplatin)
• Previous experience of severe nausea or vomiting
• Being younger than 50
• A history of motion sickness or morning sickness during pregnancy

Typical Patterns of Chemotherapy-Induced Vomiting

Chemotherapy-related vomiting usually falls into three categories:

1. Acute onset
   • Occurs within the first 24 hours after treatment
   • Peaks around 5–6 hours post-infusion
2. Delayed onset
   • Begins more than 24 hours after chemotherapy
   • May continue for several days
3. Anticipatory
   • Triggered by sights, smells, or thoughts associated with prior bad experiences
   • Often seen in people who had poorly controlled nausea on earlier cycles

At-Home Management Strategies

Following the latest ASCO and MASCC/ESMO antiemetic guidelines, you can take steps to minimize vomiting:

• Scheduled antiemetics
– 5-HT3 receptor antagonists (ondansetron, palonosetron)
– NK1 receptor antagonists (aprepitant, fosaprepitant)
– Dexamethasone
– Olanzapine for breakthrough symptoms

• Hydration
– Sip small amounts of water, electrolyte drinks, or clear broths every 15–30 minutes
– Avoid large volumes at once to prevent further nausea

• Diet adjustments
– Eat bland, dry foods (toast, crackers, rice)
– Take small, frequent meals rather than three large ones
– Avoid greasy, spicy, or strong-smelling foods

• Complementary approaches
– Ginger supplements or ginger tea
– Acupressure wristbands
– Relaxation techniques, deep breathing, guided imagery

• Symptom tracking
– Keep a log of when you take chemo, antiemetics, meals, fluids, and vomiting episodes
– Note any triggers or patterns

Warning Signs: When to Call Your Doctor

It’s normal to have mild nausea or one-off vomiting after chemotherapy—but call your doctor if you experience any of the following:

• Persistent or worsening vomiting
– More than 3–4 episodes in 24 hours despite taking prescribed antiemetics
– Vomiting that interferes with your ability to eat or drink at all

• Signs of dehydration
– Dark yellow, concentrated urine or no urine for 6–8 hours
– Dry mouth, cracked lips, sunken eyes
– Dizziness, lightheadedness when standing
– Rapid heartbeat or low blood pressure

• Blood or unusual material in vomit
– Bright red blood (active bleeding)
– “Coffee-ground” appearance (digested blood)

• Severe abdominal pain or bloating
– Could signal a blockage or gastrointestinal complication

• Neurological symptoms
– Confusion, severe headache, vision changes
– Suggests possible electrolyte imbalance or central nervous system effects

• Chest pain or trouble breathing
– Could indicate aspiration (inhaling vomit into the lungs)

• Fever over 100.4°F (38°C)
– Especially if you’re neutropenic (low white blood cell count)

If you’re unsure whether your symptoms are serious, you might consider doing a free, online “symptom check for” chemotherapy side effects vomiting with UbieHealth to help decide if you need immediate medical attention.

What to Expect When You Call

When you contact your oncology nurse or doctor, be ready to describe:

• Which chemotherapy drugs and doses you received
• Timing and frequency of vomiting episodes
• Current antiemetic schedule and whether you’re taking them as prescribed
• Signs of dehydration or other symptoms (fever, pain, confusion)

Your healthcare team may recommend:

• Adjusting or adding antiemetics (e.g., second-generation 5-HT3 antagonists, olanzapine)
• Urgent clinic visit for IV fluids and electrolyte replacement
• Short-term hospital admission if dehydration or nutrition issues are severe

Preventing Future Episodes

To reduce the risk of vomiting in future chemotherapy cycles:

• Take antiemetics exactly as prescribed, even if you feel fine
• Plan meals and hydration around your chemo schedule
• Report any breakthrough nausea or vomiting promptly
• Discuss prophylactic changes with your doctor—sometimes adding a new class of antiemetic prevents delayed vomiting

When to Seek Emergency Care

Call emergency services (e.g., 911) or go to the nearest emergency department if you experience:

• Loss of consciousness or unresponsiveness
• Seizures
• Sudden, severe chest pain or shortness of breath
• Inability to keep down any fluids for 24 hours accompanied by rapid heartbeat or fainting
• Severe confusion or inability to communicate

Speak to Your Doctor

Your oncology team is best equipped to adjust antiemetic regimens and manage complications. Always speak to a doctor about any vomiting that is severe, persistent, or accompanied by concerning symptoms. Early intervention can prevent dehydration, hospital admissions, and interruptions in your chemotherapy schedule.

Remember, effective control of chemotherapy side effects is a key part of your overall treatment plan. Don’t hesitate to reach out whenever you’re in doubt—your comfort and safety are their priority.