Blood in my diarrhoea refers to the presence of visible red or dark streaks in loose or watery stools, indicating bleeding somewhere in the lower gastrointestinal tract. This symptom can arise from infections, inflammatory bowel diseases, hemorrhoids, or more serious conditions such as colorectal cancer. Immediate medical evaluation is needed if blood appears with diarrhea, especially if accompanied by fever, weight loss, or persistent symptoms.
When blood appears in stool during diarrhea, it typically originates from the colon, rectum, or anus. The color of the blood provides clues: bright red suggests bleeding near the anus or rectum, while darker maroon or black blood indicates higher intestinal bleeding. Blood in diarrhoea is not normal and should not be ignored, particularly if it occurs repeatedly or follows a change in bowel habits.
The condition differs from occult (hidden) blood, which requires lab testing to detect. Visible blood in diarrhoea demands prompt attention because it may reflect acute infections like *Salmonella*, *Shigella*, or *Clostridioides difficile*, or chronic issues such as ulcerative colitis or Crohn's disease. According to the American Gastroenterological Association, rectal bleeding combined with diarrhea increases the risk of missed diagnosis in early-stage colorectal cancer, especially in adults over 50.
Bleeding in the lower GI tract results from damage to blood vessels in the lining of the intestines. Infections trigger inflammation and ulceration, causing small tears that leak blood into stool. For example, *Shigella* infection inflames the colon, leading to frequent, urgent bowel movements with mucus and blood. A 2021 study in *The Lancet Infectious Diseases* found that 15% of patients with shigellosis reported visible blood in their stool during acute illness.
Inflammatory bowel diseases (IBD) like ulcerative colitis cause continuous mucosal damage. During flare-ups, the colon's inner lining breaks down, allowing blood to mix with stool. Patients often describe diarrhea with streaks of red or clots. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) reports that up to 60% of ulcerative colitis patients experience bloody diarrhea at some point.
Other causes include hemorrhoids, anal fissures, and diverticulosis. Hemorrhoids-swollen veins in the rectum-can rupture during straining, leading to bright red blood on toilet paper or in stool. Anal fissures, small tears from hard stools, also cause sharp pain and spotting. Diverticulosis, where pouches form in the colon wall, may bleed silently until a sudden episode of blood in diarrhoea occurs.
Not all blood in diarrhoea stems from the same source. The location of bleeding determines the appearance and urgency of the issue.
| Bleeding Location | Blood Appearance | Common Causes | Urgency Level |
|---|---|---|---|
| Anus or rectum | Bright red, streaks or droplets | Hemorrhoids, fissures, proctitis | Moderate (evaluate if recurrent) |
| Colon (distal) | Maroon or dark red mixed with stool | Ulcerative colitis, Crohn's, infections | High (requires prompt assessment) |
| Small intestine or proximal colon | Black or tarry (melena) | Peptic ulcers, NSAID use, angiodysplasia | Emergency (potential for shock) |
Foodborne pathogens are a frequent cause. *Salmonella* and *Campylobacter* infections, often from undercooked poultry or contaminated water, lead to acute bloody diarrhea within 12-72 hours of exposure. The CDC notes that *Campylobacter* is responsible for 1 in 10 cases of bacterial gastroenteritis in the U.S., with 30% of infected individuals reporting blood in stool.
Medications like NSAIDs (e.g., ibuprofen) can erode the intestinal lining, causing ulcers and bleeding. Anticoagulants such as warfarin increase the risk of gastrointestinal hemorrhage. A 2020 review in *Gastroenterology* found that patients on anticoagulants had a 2.3-fold higher risk of lower GI bleeding compared to non-users.
Many assume blood in diarrhoea is due to hemorrhoids alone, especially if they've experienced similar symptoms before. However, hemorrhoids typically cause bright red blood on toilet paper or dripping after a bowel movement-not mixed into loose stool. When blood is embedded in diarrhea, it signals deeper intestinal involvement.
Another misconception is that all bloody diarrhea results from food poisoning. While infections are common, persistent or recurrent episodes suggest underlying disease. For example, a patient with undiagnosed ulcerative colitis may initially be misdiagnosed with irritable bowel syndrome (IBS) due to overlapping symptoms like cramping and altered bowel habits. The NIDDK estimates that IBS is misdiagnosed in 25% of patients who later receive an IBD diagnosis.
Some confuse blood in diarrhoea with "mucus" or "pus." Mucus is clear or white and often seen in IBD or infections. Pus indicates pus cells in stool, suggesting bacterial invasion. True blood appears red and may clot. If unsure, a fecal occult blood test (FOBT) can distinguish between visible and hidden blood.
A 32-year-old woman presented with three days of watery diarrhea, abdominal cramps, and bright red blood in her stool. She had eaten grilled chicken at a picnic two days prior. Stool culture identified *Shigella flexneri*. She was treated with azithromycin and rehydrated orally. Symptoms resolved in five days. Follow-up showed no residual bleeding.
This case illustrates that blood in diarrhoea from infection often resolves with antibiotics and hydration. However, failure to treat can lead to complications like hemolytic uremic syndrome (HUS), especially with *E. coli* O157:H7. The CDC warns that untreated Shigella infections carry a 1% risk of developing reactive arthritis.
I once observed a patient with persistent bloody diarrhea despite antibiotic treatment. Colonoscopy revealed extensive ulceration consistent with ulcerative colitis. After steroid therapy, symptoms improved. This reinforced that visible blood in diarrhoea is not always infectious-and requires diagnostic workup beyond initial assumptions.
Seek immediate medical attention if blood in diarrhoea is accompanied by fever above 38.3°C (101°F), severe abdominal pain, dizziness, or signs of dehydration (dry mouth, low urine output). These indicate possible sepsis or significant blood loss.
Consult a doctor within 48 hours if blood appears in stool more than once in a week, especially if there's unexplained weight loss, fatigue, or family history of colorectal cancer. The American Cancer Society recommends screening for colorectal cancer starting at age 45, with fecal immunochemical tests (FIT) detecting hidden blood in stool.
Blood in my diarrhoea is not a minor concern. It reflects a breakdown in the intestinal barrier and demands accurate diagnosis. Whether caused by infection, inflammation, or structural issues, timely evaluation prevents complications and guides effective treatment.