Diarrhea from Cancer Treatment

What is Treatment-Induced Diarrhea?

Diarrhea is defined as an increase in the frequency and/or liquidity of bowel movements compared to your normal pattern. In the context of cancer treatment, it typically means:

• Three or more loose or watery stools per day
• Increase of 4 or more stools per day over your baseline
• Stools that are looser in consistency than normal

How Cancer Treatment Causes Diarrhea

Different treatments cause diarrhea through various mechanisms:

Chemotherapy

• Damage to intestinal lining: Rapidly dividing cells of the GI tract are affected, similar to cancer cells
• Inflammation: Mucosal inflammation (mucositis) extends throughout digestive tract
• Altered motility: Changes in how quickly food moves through intestines
• Disrupted gut bacteria: Imbalance in normal intestinal flora

Radiation Therapy

• Direct damage: Radiation to abdomen or pelvis damages intestinal cells
• Acute radiation enteritis: Inflammation during treatment
• Chronic radiation enteritis: Long-term changes to bowel (months to years later)

Immunotherapy

• Immune-mediated colitis: Immune system attacks the colon lining
• Can be severe: Requires steroids or immunosuppression

Targeted Therapy

• EGFR inhibitors: Affect normal GI cells (cetuximab, erlotinib)
• VEGF inhibitors: Can alter intestinal function

Types of Diarrhea

Understanding the type helps guide treatment:

• Secretory: Intestines secrete excess fluid (common with chemotherapy)
• Osmotic: Unabsorbed substances draw water into intestines
• Inflammatory: Damage to intestinal lining with inflammation
• Motility-related: Food moves too quickly through intestines

Causes and Risk Factors

Cancer Treatments Associated with Diarrhea

High-Risk Chemotherapy (50-80% incidence)

• Irinotecan (Camptosar): 60-80% develop diarrhea
  • Early-onset (within 24 hours): Cholinergic reaction
  • Late-onset (5-10 days later): Mucosal damage, can be severe
• 5-Fluorouracil (5-FU): 30-60%, especially continuous infusion
• Capecitabine (Xeloda): Oral 5-FU prodrug, 40-50%
• FOLFOX/FOLFIRI: Combination regimens for colorectal cancer

Moderate-Risk Chemotherapy (20-50% incidence)

• Docetaxel (Taxotere): 30-40%
• Paclitaxel (Taxol): 10-30% - see paclitaxel
• Methotrexate: High-dose regimens
• Cytarabine (Ara-C): High-dose

Targeted Therapies

• EGFR inhibitors: Cetuximab (Erbitux) 20-30%, erlotinib (Tarceva) 50-60%
• VEGF inhibitors: Bevacizumab (Avastin), regorafenib
• Tyrosine kinase inhibitors: Sorafenib, sunitinib, dasatinib

Immunotherapy

• Checkpoint inhibitors: Pembrolizumab, nivolumab, ipilimumab
  • Immune-related adverse event (irAE)
  • Can be severe and require steroids
  • More common with CTLA-4 inhibitors (ipilimumab)

Radiation Therapy

• Abdomen or pelvis radiation: 50-80% develop diarrhea
• Higher risk with: Larger treatment fields, higher doses, concurrent chemotherapy
• Cancers: Rectal, cervical, prostate, bladder, gynecologic cancers

Other Contributing Factors

• Infections: C. difficile (after antibiotics), viral, bacterial
• Antibiotics: Disrupt normal gut bacteria
• Medications: Pain medications (especially magnesium-containing), antacids
• Dietary: Lactose intolerance, high fiber, high fat, sugar alcohols (sorbitol)
• Anxiety and stress: Can worsen bowel symptoms
• Partial bowel obstruction: Can cause paradoxical diarrhea
• Pancreatic insufficiency: After pancreatic surgery or radiation

Patient Risk Factors

• Previous abdominal or pelvic surgery
• History of irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD)
• Lactose intolerance
• Poor nutritional status
• Concurrent infections

Severity Grading

Healthcare providers use the NCI-CTCAE (Common Terminology Criteria for Adverse Events) to grade diarrhea severity:

When to Report to Your Doctor

• Grade 1: Monitor, start dietary modifications and loperamide as directed
• Grade 2: Call your oncology team, may need prescription medications
• Grade 3-4: Call immediately or go to emergency room

Keep a Diary

Track the following information to share with your healthcare team:

• Number of bowel movements per day
• Consistency (watery, loose, soft, formed)
• Color (especially note black or red stools)
• Associated symptoms (cramping, urgency, incontinence)
• Medications taken (anti-diarrheal, antibiotics, other)
• Foods and fluids consumed
• Impact on daily activities and sleep

Prevention Strategies

While you can't always prevent treatment-induced diarrhea, you can reduce risk and severity:

Before Starting Treatment

• Discuss risk: Ask your oncologist which treatments are most likely to cause diarrhea
• Get loperamide (Imodium): Have it on hand before symptoms start
• Know when to call: Understand the warning signs requiring medical attention
• Baseline bowel habits: Establish what's normal for you

Dietary Prevention

• Avoid trigger foods: High fat, high fiber, spicy, dairy (if lactose intolerant), caffeine, alcohol
• Eat smaller meals: 5-6 small meals rather than 3 large ones
• Stay hydrated: Drink 8-10 cups of clear fluids daily
• Probiotics: Some evidence they may help (discuss with doctor first)

Medication Prevention

For irinotecan specifically:

• Early-onset diarrhea: Atropine 0.25-1 mg IV/SC can prevent cholinergic symptoms
• Late-onset diarrhea: Aggressive loperamide at first sign (see treatment section)

Radiation Patients

• Low-residue diet: Start when radiation begins
• Avoid gas-producing foods: Beans, broccoli, cabbage, carbonated beverages
• Lactose-free diet: Radiation can cause temporary lactose intolerance

Treatment and Medications

Treatment depends on severity and underlying cause.

First-Line Treatment: Loperamide (Imodium)

Loperamide is an over-the-counter anti-diarrheal medication that slows intestinal motility.

Standard Dosing (Mild-Moderate Diarrhea)

• Initial dose: 4 mg (2 capsules) after first loose stool
• Maintenance: 2 mg (1 capsule) after each subsequent loose stool
• Maximum: 16 mg/day (8 capsules) for no more than 2 days without consulting doctor

High-Dose Loperamide (Irinotecan-Induced Diarrhea)

For severe chemotherapy-induced diarrhea, higher doses are often needed:

• Initial dose: 4 mg (2 capsules) at first sign of loose stool
• Maintenance: 2 mg every 2 hours during the day AND 4 mg every 4 hours at night
• Continue: Until 12 hours diarrhea-free, then discontinue
• Maximum: Can exceed standard OTC limits under physician supervision

Second-Line Medications

If loperamide is ineffective, your doctor may prescribe:

Diphenoxylate/Atropine (Lomotil)

• Prescription only
• Dosing: 2 tablets 4 times daily, then reduce as symptoms improve
• Similar mechanism to loperamide but stronger

Octreotide (Sandostatin)

• For severe, refractory diarrhea not responding to loperamide
• Mechanism: Synthetic somatostatin analog that reduces intestinal secretions
• Route: Subcutaneous injection
• Dosing: 100-150 mcg SC 3 times daily, can increase to 500 mcg 3 times daily
• Use: Especially for chemotherapy-induced or radiation-induced diarrhea

Tincture of Opium

• Reserved for severe cases
• Controlled substance (narcotic)
• Very effective but risk of dependence

Treatment for Specific Causes

Immune-Related Diarrhea (Immunotherapy)

• Grade 1: Loperamide, dietary modifications
• Grade 2-3: Hold immunotherapy, start corticosteroids (prednisone 1 mg/kg/day or equivalent)
• Grade 4 or no improvement: Hospitalization, IV steroids, consider infliximab (Remicade) or other immunosuppressants
• Taper steroids slowly over 4-6 weeks once improved

Infection-Related Diarrhea

• C. difficile: Oral vancomycin or fidaxomicin (test stool if recent antibiotic use or hospitalization)
• Bacterial gastroenteritis: Usually supportive care, antibiotics if severe
• Viral: Supportive care only

Pancreatic Insufficiency

• Pancreatic enzymes: Creon, Pancrelipase with meals
• Improves fat absorption if pancreas not producing enough digestive enzymes

Hospitalization Indications

You may need hospital admission for:

• IV hydration and electrolyte replacement
• Grade 3-4 diarrhea
• Signs of dehydration or shock
• Inability to maintain oral intake
• Severe electrolyte abnormalities (low potassium, low sodium)
• Concern for serious infection
• Monitoring while on IV octreotide or other intensive therapies

Dietary Management

Diet plays a crucial role in managing diarrhea. The goals are to slow bowel movements, prevent dehydration, and minimize irritation.

BRAT Diet (Initial Phase)

When diarrhea is active, start with bland, low-fiber foods:

• B - Bananas: Easy to digest, provide potassium
• R - Rice: White rice, binding effect
• A - Applesauce: Pectin helps firm stools
• T - Toast: White bread toast, easy to digest

Low-Residue, Low-Fiber Diet

Recommended during active diarrhea and for radiation patients:

Foods to CHOOSE

• Proteins:
  • Lean meats: Chicken, turkey, fish (baked, broiled, not fried)
  • Eggs (cooked, not raw)
  • Smooth nut butters in small amounts
• Grains:
  • White rice, white pasta, white bread
  • Cream of wheat, cream of rice
  • Plain crackers (saltines)
  • Pretzels
• Fruits:
  • Bananas
  • Applesauce
  • Canned peaches or pears (no skin)
  • Fruit juices without pulp
• Vegetables:
  • Well-cooked vegetables without skin or seeds
  • Peeled potatoes
  • Carrots (cooked and soft)
  • Green beans (well-cooked)
• Dairy (if tolerated):
  • Lactose-free milk or alternatives (almond, rice milk)
  • Yogurt (may help due to probiotics, but avoid if lactose intolerant)
  • Small amounts of cheese

Foods to AVOID

• High-fiber foods:
  • Whole grains, bran, brown rice
  • Raw fruits and vegetables
  • Nuts and seeds
  • Popcorn
  • Dried fruits (prunes, raisins)
• Dairy (if lactose intolerant):
  • Milk, ice cream, cream
  • Large amounts of cheese
• Fatty and fried foods:
  • Fried chicken, french fries
  • Fatty cuts of meat
  • Rich sauces and gravies
  • Creamy soups
• Gas-producing foods:
  • Beans and legumes
  • Broccoli, cauliflower, cabbage, Brussels sprouts
  • Onions, garlic
  • Carbonated beverages
• Spicy foods:
  • Hot peppers, curry, hot sauce
• Stimulants:
  • Caffeine (coffee, tea, cola, energy drinks)
  • Alcohol
• Sugar alcohols:
  • Sorbitol, mannitol, xylitol (in sugar-free gum, candies)

Eating Tips

• Small, frequent meals: 5-6 small meals instead of 3 large ones
• Room temperature or warm: Avoid very hot or very cold foods
• Eat slowly: Chew food well
• Limit portions: Don't overeat at one sitting
• Avoid eating 2-3 hours before bedtime to reduce nighttime symptoms

Gradual Reintroduction

Once diarrhea resolves (24-48 hours of normal stools):

• Slowly add back one food at a time
• Wait 24 hours before adding another new food
• If symptoms return, remove that food
• Gradually increase fiber over weeks

Probiotics

• Some evidence of benefit for preventing antibiotic-associated and radiation-induced diarrhea
• Common strains: Lactobacillus, Bifidobacterium, Saccharomyces boulardii
• Yogurt with live cultures or probiotic supplements
• Discuss with doctor first: May not be safe if severely immunocompromised

Staying Hydrated

Dehydration is the most dangerous complication of diarrhea. Aggressive fluid replacement is essential.

How Much to Drink

• Baseline: 8-10 cups (64-80 oz) of fluid daily
• With diarrhea: Replace each loose stool with 1 cup (8 oz) of fluid
• Example: If you have 8 stools/day, drink 8-10 baseline + 8 replacement = 16-18 cups total

Best Fluids

Electrolyte Solutions (Best Choice)

• Oral rehydration solutions: Pedialyte, CeraLyte, WHO oral rehydration salts
• Sports drinks: Gatorade, Powerade (dilute 50/50 with water to reduce sugar)
• Broth: Chicken, beef, or vegetable broth (provides sodium)
• Why important: Replace not just water but also sodium, potassium, chloride lost in diarrhea

Other Good Choices

• Water (plain or with electrolyte tablets)
• Weak tea (decaffeinated)
• Clear fruit juices (apple, white grape) - diluted
• Ginger ale (flat, not carbonated)
• Popsicles or ice chips

Fluids to Limit or Avoid

• Caffeine: Coffee, tea, cola (stimulates bowels and is dehydrating)
• Alcohol: Dehydrating and irritating
• High-sugar drinks: Can worsen diarrhea osmotically (undiluted juice, soda)
• Prune juice: Has laxative effect
• Milk: If lactose intolerant (common during treatment)

Signs of Dehydration

Mild to Moderate:

• Thirst
• Dry mouth and lips
• Dark yellow urine
• Decreased urine output
• Fatigue
• Headache

Severe (Call Doctor Immediately):

• Dizziness or lightheadedness, especially when standing
• Confusion or difficulty concentrating
• Very dark urine or no urine for 8+ hours
• Rapid heartbeat
• Sunken eyes
• Extreme weakness

Electrolyte Monitoring

Your doctor may check blood tests for:

• Potassium: Lost in large amounts with diarrhea, can cause dangerous heart rhythm abnormalities if very low
• Sodium: Can become low or high depending on type of fluid loss and replacement
• Bicarbonate: Can become low (acidosis)
• Creatinine: Marker of kidney function, elevates with dehydration

IV Hydration

You may need intravenous fluids if:

• Unable to drink enough to keep up with losses
• Vomiting prevents oral intake
• Signs of moderate to severe dehydration
• Electrolyte abnormalities requiring correction

Skin Care and Comfort

Frequent diarrhea can cause painful irritation and breakdown of the skin around the anus.

Perianal Skin Care

Cleansing

• Rinse with water: After each bowel movement if possible (use squirt bottle, bidet, or shower)
• Pat dry: Gently with soft toilet paper or towel (don't rub)
• Use soft wipes: Unscented baby wipes or specially designed adult wipes (avoid wipes with alcohol)
• Sitz baths: Sit in warm water for 10-15 minutes 2-3 times daily

Protection

• Barrier creams: Apply after each bowel movement
  • Petroleum jelly (Vaseline)
  • Zinc oxide ointment (Desitin, Balmex)
  • Dimethicone-based products
  • Calmoseptine
• Protective pads: If incontinence is an issue

Avoid

• Harsh soaps: Use gentle, fragrance-free cleansers
• Rubbing: Pat or blot instead
• Perfumed products: Can irritate sensitive skin

Treatment of Skin Breakdown

If skin becomes red, raw, or develops sores:

• Keep clean and dry
• Apply thick barrier cream (zinc oxide)
• Air exposure: Let area air dry when possible
• Antifungal cream: If yeast infection develops (bright red rash with satellite lesions)
• Notify doctor: May need prescription treatments

Comfort Measures

• Hemorrhoid cushion: Donut-shaped pillow for sitting
• Loose clothing: Avoid tight underwear or pants
• Cotton underwear: More breathable than synthetic
• Nighttime protection: Waterproof mattress pad if nighttime accidents occur

Managing Urgency and Incontinence

• Plan ahead: Know where bathrooms are located when out
• Limit social activities: During severe diarrhea, stay close to home
• Protective garments: Adult incontinence products if needed (no shame - this is a medical issue!)
• Bedside commode: If mobility is an issue or nighttime urgency

Complications

Acute Complications

Dehydration

• Most common and dangerous complication
• Can lead to kidney damage, shock, death if severe
• Requires IV fluid replacement

Electrolyte Imbalances

• Hypokalemia (low potassium): Causes weakness, heart arrhythmias
• Hyponatremia (low sodium): Causes confusion, seizures
• Metabolic acidosis: Loss of bicarbonate
• Treatment: IV or oral electrolyte replacement

Malnutrition

• Poor absorption of nutrients
• Reduced oral intake due to fear of worsening diarrhea
• Weight loss, muscle wasting
• Vitamin and mineral deficiencies

Infections

• C. difficile colitis: Especially if recent antibiotics or hospitalization
• Sepsis: If bacteria enter bloodstream through damaged intestinal lining
• Perianal abscess: From skin breakdown

Acute Kidney Injury

• From severe dehydration
• Usually reversible with fluid resuscitation
• Monitor creatinine levels

Treatment-Related Complications

Chemotherapy Dose Delays or Reductions

• Grade 3-4 diarrhea may require dose modifications
• Can impact cancer treatment efficacy
• Balance between controlling cancer and managing side effects

Hospitalization

• 15-30% of patients with severe chemotherapy-induced diarrhea require hospitalization
• Average stay: 3-7 days
• For IV hydration, electrolyte correction, monitoring

Chronic Complications (Rare)

Chronic Radiation Enteritis

• Can develop months to years after pelvic radiation
• Permanent damage to intestines
• Chronic diarrhea, bleeding, malabsorption
• May require long-term dietary modifications, medications

Lactose Intolerance

• Chemotherapy and radiation can damage lactase-producing cells
• Usually temporary but can be permanent
• Requires lactose-free diet

Impact on Quality of Life

• Anxiety about leaving home
• Sleep disruption from nighttime diarrhea
• Social isolation
• Embarrassment and emotional distress
• Work/school absences
• Financial impact from hospitalizations, medications

Frequently Asked Questions