Is It a Diverticulitis Flare? How Your Stool Changes During Inflammation

Is It a Diverticulitis Flare? How Your Stool Changes During Inflammation

If you live with diverticulosis—or have had diverticulitis before—you may wonder whether new bowel changes mean a flare is starting. Diverticulitis stool changes can be confusing and uncomfortable, and they don't look the same for everyone. This guide explains what typically happens to your stool during inflammation, why it happens, and when it's important to get medical care.

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Quick refresher: What is diverticulitis?

Diverticula are small pouches that can form in the lining of the colon, most often as we age. Many people have diverticula and never have symptoms (this is called diverticulosis). Diverticulitis occurs when one or more of these pouches become inflamed or infected.

When inflammation affects the colon, it can directly change how stool looks, feels, and moves through your digestive tract.

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Common Diverticulitis Stool Changes

During a diverticulitis flare, inflammation can narrow parts of the colon, irritate the lining, and disrupt normal muscle movement. As a result, stool changes are common.

1. Constipation

Constipation is one of the most frequent diverticulitis stool changes.

You may notice:

• Fewer bowel movements than usual
• Hard, dry stools
• Straining or a feeling of incomplete emptying

Why it happens:
Inflammation can cause the colon to spasm or narrow, slowing stool movement. Pain may also make people avoid going to the bathroom, which worsens constipation.

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2. Diarrhea or Loose Stools

Some people experience the opposite problem—loose or watery stools.

Possible features include:

• Frequent bowel movements
• Urgent need to go
• Softer or watery stool consistency

Why it happens:
Inflammation can irritate the colon lining and interfere with water absorption. If infection is present, the body may push stool through faster as a defense mechanism.

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3. Alternating Constipation and Diarrhea

It's not unusual to swing between constipation and diarrhea during a flare.

This pattern may happen because:

• Inflamed areas slow stool in some sections
• Irritation speeds things up in others

This back-and-forth can feel unpredictable and frustrating, but it is a recognized pattern during active inflammation.

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4. Narrow or Ribbon-Like Stools

Some people notice stools that look thinner than usual.

What this can mean:

• Swelling in the colon can temporarily narrow the passageway
• Stool is shaped as it passes through tighter areas

Occasional narrow stools during a flare can happen. However, persistently thin stools, especially without pain, should be discussed with a doctor.

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5. Mucus in the Stool

Mucus may appear as a clear or whitish coating on stool or on toilet paper.

Why mucus appears:

• The colon produces extra mucus to protect inflamed tissue
• Irritation increases mucus secretion

Small amounts of mucus can occur during diverticulitis, especially when diarrhea is present.

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6. Blood in the Stool

Blood can be alarming, and it's important not to ignore it.

You may see:

• Bright red blood on toilet paper or in the bowl
• Darker or maroon-colored stool

Important note:
While bleeding can occur with diverticular disease, blood in the stool is not something to self-diagnose. It can have many causes—some serious—and always warrants medical advice.

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Other Symptoms That Often Accompany Stool Changes

Stool changes rarely happen alone during diverticulitis. They are often paired with:

• Lower left abdominal pain or tenderness
• Bloating or gas
• Fever or chills
• Nausea or loss of appetite

The combination of these symptoms makes diverticulitis more likely than a simple digestive upset.

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How Diverticulitis Stool Changes Differ From Other Conditions

Many bowel conditions overlap. Understanding the differences can help you decide what to do next.

• Irritable Bowel Syndrome (IBS):
  Stool changes are common, but IBS does not cause fever, infection, or inflammation seen on imaging.

• Stomach flu or food poisoning:
  Usually causes sudden diarrhea and vomiting and improves within days.

• Colon infections:
  Often cause severe diarrhea, fever, and dehydration.

• Colon cancer:
  May cause ongoing stool shape changes or bleeding without pain.

Because symptoms can be hard to interpret on your own, using a free AI-powered symptom checker for Diverticulitis can help you quickly assess whether your stool changes and other symptoms match a typical flare pattern.

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What to Do During a Suspected Flare

If you think your stool changes may be related to diverticulitis, gentle care is important.

During acute symptoms:

• Follow your doctor's advice about diet (often clear liquids at first)
• Stay well hydrated
• Avoid laxatives unless a doctor approves
• Rest and avoid heavy activity

As symptoms improve:

• Gradually reintroduce low-fiber foods
• Transition back to fiber slowly once inflammation settles

Never start antibiotics or pain medications without medical guidance.

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When Stool Changes Are More Concerning

While many flares are uncomplicated, some signs suggest you need prompt medical care.

Seek medical advice right away if you have:

• Severe or worsening abdominal pain
• Persistent fever
• Vomiting that prevents drinking fluids
• Significant or ongoing blood in your stool
• Black, tarry stools
• Signs of dehydration or weakness

These symptoms can point to complications such as abscess, perforation, or obstruction, which require urgent treatment.

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Can Stool Look Normal During Diverticulitis?

Yes. Some people have classic abdominal pain and fever with minimal stool changes. Others notice bowel changes days before pain starts. Every flare can be different, even in the same person.

That's why it's important to look at patterns, not just one bowel movement.

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Long-Term Outlook and Prevention

After a flare resolves, many people worry about recurrence.

To reduce future risk, doctors often recommend:

• A high-fiber diet once healed
• Drinking enough water
• Regular physical activity
• Managing constipation early

Stool consistency often normalizes between flares, but staying alert to new changes can help catch problems early.

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The Bottom Line

Diverticulitis stool changes can include constipation, diarrhea, narrow stools, mucus, or even blood. These changes happen because inflammation affects how stool moves through and is formed in the colon. While many changes are uncomfortable but manageable, some require medical attention.

If you're experiencing unusual bowel changes along with abdominal discomfort, try the Diverticulitis symptom checker to better understand your symptoms and determine if you need to seek medical care.

Most importantly, speak to a doctor about any symptoms that feel severe, unusual, or potentially life-threatening. Early medical guidance can make a meaningful difference in recovery and long-term colon health.