Why is my diarrhea bloody and persistent?

Why Is My Diarrhea Bloody and Persistent?

Diarrhea is common and often short-lived, but when it becomes bloody and persistent, it deserves careful attention. Bloody diarrhea means there is visible blood or dark, tarry material mixed with loose or watery stools. Persistent usually means it lasts more than a few days or keeps coming back. Together, these symptoms can point to irritation, infection, inflammation, or other conditions affecting the digestive tract.

This article explains the most common and credible medical reasons for bloody, ongoing diarrhea, what symptoms to watch for, and when to seek medical care—using clear language without unnecessary alarm.

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Understanding What Bloody Diarrhea Means

Blood in diarrhea usually comes from the lower digestive tract, such as the colon or rectum, though darker blood can sometimes come from higher up. The color and amount of blood can offer clues:

• Bright red blood often suggests bleeding closer to the rectum or colon
• Maroon or dark red blood may come from deeper in the colon
• Black, tarry stools can signal bleeding higher in the digestive system

Persistent diarrhea means the bowel lining may be inflamed, infected, or damaged, which allows blood to leak into stool.

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Common Causes of Bloody and Persistent Diarrhea

1. Infections of the Gut

Certain infections are a leading cause of bloody diarrhea.

Bacterial infections are especially common, including:

• Salmonella
• Shigella
• Campylobacter
• Certain strains of E. coli

These bacteria can enter the body through:

• Undercooked meat
• Unpasteurized milk or juice
• Contaminated water
• Poor hand hygiene

Symptoms often include:

• Diarrhea that lasts several days
• Blood or mucus in stool
• Fever
• Abdominal cramping

Some parasitic infections can also cause persistent diarrhea with blood, particularly after travel or exposure to untreated water.

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2. Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease includes:

• Ulcerative colitis
• Crohn's disease

These are chronic conditions where the immune system causes ongoing inflammation in the digestive tract.

Common signs include:

• Persistent diarrhea
• Blood or mucus in stool
• Urgency to have a bowel movement
• Abdominal pain
• Fatigue or unintended weight loss

IBD is not caused by infection and often requires long-term medical care.

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3. Irritable Bowel Syndrome With Another Condition

Irritable bowel syndrome (IBS) does not cause bleeding on its own. However, people with IBS may also have:

• Hemorrhoids
• Anal fissures
• Infections or inflammation

If you have IBS and notice blood, it's important to look for another cause.

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4. Hemorrhoids and Anal Fissures

Sometimes blood appears during diarrhea because of local irritation, not disease inside the bowel.

• Hemorrhoids are swollen blood vessels near the rectum
• Anal fissures are small tears in the anal lining

These can cause:

• Bright red blood on toilet paper
• Blood streaks on stool
• Pain or burning during bowel movements

While common, bleeding should still be discussed with a doctor if diarrhea is persistent.

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5. Reduced Blood Flow to the Colon (Ischemic Colitis)

When blood flow to part of the colon is reduced, the tissue can become inflamed and bleed.

This may occur in:

• Older adults
• People with heart or blood vessel disease
• Severe dehydration

Symptoms can include:

• Sudden abdominal pain
• Bloody diarrhea
• Urgent need to use the bathroom

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6. Medication-Related Causes

Certain medications can irritate the digestive tract or increase bleeding risk, such as:

• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Some antibiotics
• Blood thinners

Antibiotics can also disrupt healthy gut bacteria, sometimes leading to infections that cause persistent diarrhea with blood.

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7. Colon Polyps or Cancer

While less common, ongoing bloody diarrhea can be a sign of:

• Colon polyps
• Colorectal cancer

Other symptoms may include:

• Changes in bowel habits
• Unexplained weight loss
• Ongoing fatigue

Early evaluation improves outcomes, which is why persistent symptoms should not be ignored.

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When Bloody Diarrhea Is More Concerning

You should speak to a doctor promptly if diarrhea with blood is accompanied by:

• Fever above 101°F (38.3°C)
• Severe or worsening abdominal pain
• Signs of dehydration (dry mouth, dark urine, dizziness)
• Black or tarry stools
• Nighttime symptoms that wake you from sleep
• Diarrhea lasting longer than 3–5 days
• A weakened immune system, pregnancy, or advanced age

These signs may point to a condition that needs urgent evaluation or treatment.

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How Doctors Evaluate Bloody, Persistent Diarrhea

A healthcare professional may recommend:

• Stool tests to check for bacteria, parasites, or inflammation
• Blood tests to look for infection, anemia, or inflammation
• Imaging tests if complications are suspected
• Colonoscopy to examine the colon directly when needed

The goal is to identify the cause and guide appropriate treatment.

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What You Can Do While Waiting for Care

While evaluation is important, these steps may help reduce discomfort:

• Drink fluids with electrolytes to prevent dehydration
• Eat bland foods (such as rice, bananas, toast) if tolerated
• Avoid alcohol, caffeine, and very fatty foods
• Do not take anti-diarrheal medications unless a doctor says it's safe, especially when blood is present

Tracking your symptoms—including frequency, appearance of stool, and associated pain—can help your doctor.

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Using a Symptom Checker as a Starting Point

If you're unsure what might be causing your symptoms or need help deciding whether to contact your doctor, a free diarrhea symptom checker can help you assess your condition and understand possible causes based on the symptoms you're experiencing. This tool can be especially useful for organizing your concerns before your medical appointment, though it should never replace professional medical advice.

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The Importance of Medical Guidance

Bloody and persistent diarrhea is not something to self-diagnose or ignore. Many causes are treatable, especially when addressed early. Others require ongoing care to prevent complications.

If there is any concern that symptoms could be serious or life-threatening, or if bleeding continues, speak to a doctor as soon as possible. Prompt medical advice ensures you get the right tests, treatment, and peace of mind.

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Key Takeaway

Diarrhea that is bloody and persistent often signals inflammation, infection, or damage in the digestive tract. While some causes are mild and temporary, others require medical evaluation. Paying attention to warning signs, staying hydrated, and seeking professional care are the most reliable ways to protect your health.