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Constipation

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

What is Constipation? Constipation is infrequent or difficult passage of stools. Medical definition typically includes having fewer than 3 bowel movements per week, hard or lumpy stools, excessive straining, sensation of incomplete evacuation, or needing manual assistance to pass stools.

Overview

Constipation is one of the most common side effects experienced by cancer patients, affecting 40-60% of people during treatment. While often dismissed as a minor inconvenience, severe constipation can significantly impact quality of life, interfere with eating and daily activities, and in rare cases lead to serious complications.

Unlike diarrhea (which is often directly caused by chemotherapy damaging intestinal cells), constipation in cancer patients is usually multifactorial - caused by a combination of medications (especially opioid pain relievers and anti-nausea drugs), decreased activity, dietary changes, dehydration, and sometimes the cancer itself. The good news is that constipation is highly preventable and treatable with proper management.

Causes of Constipation in Cancer Patients

Medications (Most Common Cause)

Opioid Pain Medications (Primary Culprit)

Anti-Nausea Medications (Antiemetics)

Chemotherapy Drugs

Other Medications

Decreased Physical Activity

Dietary Changes

Dehydration

Metabolic and Tumor-Related Causes

Psychological Factors

Symptoms and Complications

Common Symptoms

Severe Complications

When to Seek Immediate Medical Attention:
  • No bowel movement for 3-4 days despite laxatives (especially if on opioids or vincristine)
  • Severe abdominal pain or distension
  • Nausea and vomiting with constipation
  • Inability to pass gas
  • Rectal bleeding (more than small streaks from straining)
  • Signs of bowel obstruction

Prevention Strategies

Prevention is Key: It is much easier to prevent constipation than to treat severe constipation or impaction. If you are starting opioid pain medications, anti-nausea drugs, or vincristine, begin a bowel regimen immediately - don't wait for constipation to develop.

Bowel Regimen for Opioid Users

Everyone on regular opioids should start a bowel regimen on Day 1:

Standard Regimen:

If Not Effective, Add:

Prescription Options for Severe Opioid-Induced Constipation:

Dietary Modifications

Increase Fiber Intake

Specific Foods That May Help

Hydration

Physical Activity

Bowel Habits and Routine

Treatment Options

Types of Laxatives

Bulk-Forming Laxatives (Fiber Supplements)

Stool Softeners (Emollients)

Osmotic Laxatives

Stimulant Laxatives

Rectal Treatments

Stepwise Approach to Treatment

For Mild Constipation (No bowel movement for 2 days):

  1. Start or increase osmotic laxative (MiraLAX 17 g daily)
  2. Ensure adequate hydration and physical activity
  3. Continue stool softener if already taking

For Moderate Constipation (No bowel movement for 3-4 days):

  1. Add stimulant laxative (senna 2-4 tablets at bedtime) if not already taking
  2. Increase osmotic laxative dose (MiraLAX twice daily)
  3. Consider magnesium citrate for quicker relief

For Severe Constipation (No bowel movement for >4 days, significant discomfort):

  1. Bisacodyl suppository or Fleet enema for immediate relief
  2. Contact healthcare team
  3. If no response within 4-6 hours, may need evaluation for impaction

For Fecal Impaction:

Combination Therapy

Often multiple laxatives are used together for maximum effect:

Special Considerations

Opioid-Induced Constipation (OIC)

Vincristine-Induced Constipation

Patients with Bowel Obstruction Risk

Patients on Low-Residue Diet

Monitoring and Communication

Keep a Bowel Diary

Track the following information to share with healthcare team:

Bristol Stool Chart

Standardized tool to describe stool consistency:

Goal during cancer treatment: Types 3-4

When to Contact Healthcare Team

Frequently Asked Questions

How often should I have a bowel movement during cancer treatment?

There is significant individual variation, but generally you should aim for a bowel movement at least every 1-2 days. More important than frequency is consistency with your normal pattern - a significant change (e.g., daily to every 4-5 days) indicates constipation even if still in "normal" range. If you're on opioids, expect changes and use a proactive bowel regimen.

Will I become dependent on laxatives?

Physical dependence on laxatives is rare and primarily a concern with very long-term daily use of stimulant laxatives (years, not weeks or months). During cancer treatment, the benefits of regular laxative use far outweigh concerns about dependence. Osmotic laxatives (MiraLAX, lactulose) do not cause dependence. Many patients require laxatives as long as they're on opioids or certain chemotherapy - this is expected and appropriate management.

Should I stop my laxatives once I have a bowel movement?

It depends. If you're on opioids or medications that cause constipation, continue your maintenance bowel regimen daily - don't stop and restart. The goal is regular soft bowel movements every 1-2 days, not alternating between constipation and diarrhea. You can adjust the dose based on response (e.g., reduce senna from 4 tablets to 2 if stools become too loose), but don't stop completely unless instructed by your healthcare team.

Can I use laxatives every day?

Yes, many patients on opioids or certain chemotherapy need daily laxatives throughout treatment. Osmotic laxatives (MiraLAX, lactulose) and stool softeners can be used daily indefinitely. Stimulant laxatives (senna, bisacodyl) can be used daily for weeks to months during cancer treatment without harm. The risk of "lazy bowel" from laxatives is overstated and should not prevent appropriate constipation management.

Why do I have diarrhea when I'm constipated?

This is called "paradoxical diarrhea" or overflow diarrhea. It occurs when liquid stool seeps around a hard fecal impaction in the rectum or colon. The liquid stool leaks out while the solid impaction remains stuck. This is a sign of severe constipation requiring medical attention - do NOT take anti-diarrheal medication, as it will worsen the impaction. You need treatment to clear the impaction (enemas, manual disimpaction).

Which foods should I avoid if I'm constipated?

Limit foods that can worsen constipation: white bread, white rice, cheese, red meat, processed foods, bananas (unripe), and excessive dairy. These are low in fiber and can slow bowel motility. However, don't eliminate entire food groups - focus on adding high-fiber foods, staying hydrated, and using laxatives as needed rather than overly restricting diet.

Is it safe to strain to have a bowel movement?

No, excessive straining should be avoided. Straining increases risk of hemorrhoids, anal fissures, rectal prolapse, and can be dangerous if you have low platelet counts (bleeding risk) or heart conditions. If you need to strain excessively, your stool is too hard - increase laxatives, fluids, and fiber rather than forcing bowel movements. Use proper positioning (feet elevated) and allow adequate time.

Can prune juice really help with constipation?

Yes, prune juice is an effective natural laxative. Prunes (dried plums) contain sorbitol, a sugar alcohol that acts as an osmotic laxative, plus fiber and phenolic compounds that stimulate bowel motility. 4-6 prunes or 4-8 oz prune juice daily can help. However, for medication-induced constipation (especially opioids), prune juice alone is usually insufficient - you'll still need laxatives.

What if I can't tolerate taking so many pills for bowel management?

Talk to your healthcare team about alternatives. Options include: liquid formulations (lactulose, magnesium hydroxide), powders that dissolve in beverages (MiraLAX), suppositories, or combination products (Senna-S combines stimulant and stool softener). Reducing pill burden while maintaining bowel function is possible with some creativity.

Should I exercise even if I feel tired and weak?

Even light activity helps constipation. You don't need vigorous exercise - simply walking to the bathroom, around your house, or outside for 5-10 minutes several times daily can stimulate bowel function. If bedridden, try changing positions, gentle leg movements, or abdominal massage. Do what you can safely tolerate, and always consult with your healthcare team about appropriate activity level.

When is constipation a medical emergency?

Seek immediate medical attention if you have: no bowel movement or gas for several days with severe abdominal pain and distension, persistent nausea and vomiting with constipation, signs of bowel obstruction, vomiting that looks or smells like stool, severe rectal pain or significant bleeding, or inability to pass stool despite multiple laxatives and enemas. These could indicate bowel obstruction or severe impaction requiring urgent treatment.

Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or qualified health provider with questions regarding a medical condition. Never disregard professional medical advice or delay seeking it because of information you have read on this website.

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