Rectal Bleeding: When Should You Be Worried?

What are the most common causes of rectal bleeding?

Blood from the lower gastrointestinal tract — appearing on toilet paper, in the toilet bowl, or mixed with stool — has a wide range of causes:

• Hemorrhoids: Swollen veins in and around the rectum and anus. Internal hemorrhoids typically produce painless bright red blood, often on the surface of the stool or on toilet paper. External hemorrhoids can cause pain, swelling, and bleeding. Hemorrhoids are extremely common and are the most frequent cause of rectal bleeding.
• Anal fissures: Small tears in the lining of the anus that cause bright red bleeding and sharp pain during and after bowel movements.
• Diverticular disease: Small pouches in the colon (diverticula) can bleed, sometimes quite briskly. Diverticular bleeding is the most common cause of significant lower GI bleeding in adults over 40, and usually stops on its own but can require intervention.
• Colorectal polyps: Polyps in the colon can occasionally bleed. Some polyps can become cancerous, which is why colorectal cancer screening — colonoscopy or stool-based tests — is recommended starting at age 45 for average-risk adults 1Ref 1Shaukat A, Kahi CJ, Burke CA, Rabeneck L, Sauer BG, Rex DK (2021).ACG Clinical Guidelines: Colorectal Cancer Screening 2021.Colonoscopy as recommended evaluation for rectal bleeding; colorectal cancer screening starting at age 45.
• Colorectal cancer: Can cause blood in the stool, either bright red or darker. Blood mixed throughout the stool (rather than just on the surface) and accompanied by changed bowel habits, weight loss, or fatigue is a more concerning pattern.
• Inflammatory bowel disease (IBD): Crohn's disease and ulcerative colitis can cause rectal bleeding, often along with diarrhea, cramping, and urgency.

How can I tell if my rectal bleeding is from hemorrhoids or something more serious?

You cannot reliably tell based on appearance alone. Bright red blood on toilet paper after a bowel movement, without pain or other symptoms, in a young and otherwise healthy adult is most often from hemorrhoids or a fissure. But this pattern can also appear with colorectal polyps or cancer.

Features that make a more serious cause more likely include: - Blood that is dark red or maroon (comes from higher in the colon) - Blood mixed into the stool rather than just coating the surface - Associated symptoms: significant change in bowel habits, narrowing of the stool, rectal pain, bloating, weight loss, or fatigue - Age over 45 without up-to-date colorectal cancer screening - Family history of colorectal cancer or polyps - Symptoms that have persisted for more than a few weeks or have worsened

The only way to know for certain is evaluation — which may include a digital rectal exam, anoscopy, sigmoidoscopy, or colonoscopy depending on the clinical picture 2Ref 2Wald A, Bharucha AE, Limketkai B, Malcolm A, Remes-Troche JM, Whitehead WE, Zutshi M (2021).ACG Clinical Guidelines: Management of Benign Anorectal Disorders.ACG guidance on anorectal causes of rectal bleeding including hemorrhoids and fissures, and appropriate evaluation.

When does rectal bleeding require urgent or emergency care?

Some presentations of rectal bleeding are emergencies and should not wait for a scheduled appointment:

• Large amounts of blood — more than a few tablespoons, or blood that fills the toilet bowl
• Blood accompanied by lightheadedness, dizziness, rapid heart rate, or near-fainting — these suggest significant blood loss
• Blood with severe abdominal pain or cramping
• Blood with fever — raises concern for infection or inflammatory disease
• Very dark or tarry black stools (melena) — this is blood that has been partly digested and points to bleeding higher up in the GI tract (stomach or small intestine), not just the colon or rectum

For all other new rectal bleeding in adults, scheduling a prompt appointment with a primary care clinician or gastroenterologist within days to a few weeks is the right step.

What will a doctor do to evaluate rectal bleeding?

Initial evaluation typically includes a thorough history, physical examination, and sometimes blood tests to check for anemia. Depending on the findings and clinical suspicion, your clinician may refer you for:

• Anoscopy or sigmoidoscopy: Examines the rectum and lower colon
• Colonoscopy: The gold standard for examining the entire colon — recommended for new rectal bleeding in adults over 45, those with risk factors, or those with rectal bleeding alongside changed bowel habits 1Ref 1Shaukat A, Kahi CJ, Burke CA, Rabeneck L, Sauer BG, Rex DK (2021).ACG Clinical Guidelines: Colorectal Cancer Screening 2021.Colonoscopy as recommended evaluation for rectal bleeding; colorectal cancer screening starting at age 452Ref 2Wald A, Bharucha AE, Limketkai B, Malcolm A, Remes-Troche JM, Whitehead WE, Zutshi M (2021).ACG Clinical Guidelines: Management of Benign Anorectal Disorders.ACG guidance on anorectal causes of rectal bleeding including hemorrhoids and fissures, and appropriate evaluation
• Stool tests or imaging in selected cases

A gastroenterologist is the specialist who performs these evaluations and manages the most common causes of rectal bleeding. Gale can help you get connected and prepare for the appointment.

What about hemorrhoid treatment while waiting for evaluation?

For mild hemorrhoid-associated bleeding, some measures can provide temporary relief while awaiting evaluation:

• Increasing dietary fiber and fluid intake to soften stools
• Avoiding straining during bowel movements
• Sitz baths (sitting in warm water for 10–15 minutes) to reduce discomfort
• Over-the-counter hemorrhoid creams for symptom relief

These measures do not substitute for evaluation and should not be used to delay seeing a clinician for persistent or worsening rectal bleeding.