Why Is There Blood in My Stool? 8 Common Causes You Shouldn’t Ignore

By By Dr Leena Dhole

BAMS, MS (General Surgery)

Proctosurgeon, Healing Hands Clinic

Understanding Blood in Stool

Blood in stool is a symptom that can worry many people, but understanding what causes it helps you respond appropriately. When you notice blood in your stool, it means there's bleeding somewhere in your digestive system.

Blood in stool causes range from common and easily treatable conditions to more serious health issues. Piles (hemorrhoids) are one of the most frequent reasons for blood in stool, especially when the bleeding is bright red and appears on the surface of your stool or on toilet paper after wiping.

Other conditions like anal fissures create small tears in the delicate lining of your anus, typically from passing hard stools. Inflammatory conditions such as ulcerative colitis or Crohn's disease cause ongoing inflammation that leads to bleeding. More serious conditions like polyps or colorectal cancer can also cause blood to appear in stool, though this bleeding might be less obvious and require medical tests to detect.

Understanding these different causes helps you know when to worry about blood in stool and when you might need to see a doctor for proper diagnosis and treatment.

What Causes Blood in Stool

Seeing blood in stool can be frightening, but understanding the blood in stool causes helps you know when to worry and when to seek care. Blood in stool is called rectal bleeding or hematochezia. The colour and appearance of blood often reveal where the bleeding occurs in your digestive system.

Reasons for blood in stool range from common, treatable conditions like piles to more serious issues requiring immediate medical attention. Sometimes you might notice painless blood in stool, while other times it comes with discomfort or pain. Some of the reasons of blood in stool are as follows:

1. Hemorrhoids

Piles are swollen blood vessels around your anus and lower rectum. They're the most common cause of visible blood in stool. You'll typically see bright red blood on toilet paper or drops in the toilet bowl. The bleeding usually happens during or right after bowel movements. Piles develop when pressure builds up from:

• Straining during bowel movements
• Chronic constipation
• Sitting for long periods
• Heavy lifting or pregnancy

2. Anal Fissures

These are small tears in your anal lining caused by passing hard or large stools. Fissures cause sharp, burning pain during bowel movements along with bright red bleeding.

Unlike piles, fissure bleeding usually comes with significant pain. You might also notice:

• Blood on toilet tissue
• Muscle spasms around the anus
• Itching or burning sensation

Most fissures heal within weeks when you soften your stools and avoid straining.

3. Diverticulosis

Small pouches called diverticula can form in your colon wall. When these pouches bleed, you might see maroon or bright red blood in your stool.

Diverticular bleeding is often painless but can be quite heavy. This condition is less common in younger Indians but increases with age, especially when following low-fiber diets.

4. Gastroenteritis or Infections

Stomach and intestinal infections cause inflammation that can lead to bloody diarrhoea. This is particularly common during monsoon season when contaminated food and water spread infections.

You'll typically experience:

• Watery or bloody diarrhoea
• Stomach cramps and nausea
• Fever and vomiting
• Dehydration

Most infections resolve with proper hydration and rest, though severe cases need medical care.

5. Colorectal Polyps and Cancer

Polyps are growths in your colon that can bleed. Some polyps may turn cancerous over time. You might notice dark red blood mixed with stool, changes in bowel habits, or unexplained weight loss.

While colorectal cancer was traditionally less common in India, rates are rising with changing diets and lifestyles.

6. Inflammatory Bowel Disease (Crohn's, Ulcerative Colitis)

These autoimmune conditions cause chronic inflammation in your digestive tract. The inflammation creates ulcers that bleed, leading to bloody diarrhoea.

IBD symptoms include persistent diarrhoea, abdominal pain, weight loss, and fatigue. These conditions require ongoing medical management.

7. Peptic Ulcers (in case of upper GI bleeding)

Stomach or duodenal ulcers can cause bleeding that shows up as black, tarry stools rather than bright red blood. This happens because stomach acid changes the blood's appearance as it travels through your system.

8. Certain Medications (NSAIDs, blood thinners)

Pain relievers like ibuprofen and blood-thinning medications increase your bleeding risk. They can cause ulcers or make existing bleeding worse.

Always tell your doctor about any bleeding if you're taking these medications.

Summary Table: 8 Common Causes of Blood in Stool

Understanding different blood in stool causes helps you recognise when to worry about blood in stool and seek appropriate care.