Blood in Stool: Causes, What It Looks Like, and When to Worry

Common Causes of Blood in Stool

Most causes of rectal bleeding originate in the lower digestive tract and are not dangerous, but the same symptom can also flag something that needs treatment. Here are the conditions doctors see most often.

Lower digestive tract (usually bright red blood)

• Hemorrhoids: Swollen veins in or around the anus are the single most common cause of bright-red bleeding, often after straining or constipation. They may itch or be uncomfortable but are rarely serious.
• Anal fissures: A small tear in the lining of the anus, often from hard stools, causes sharp pain and a streak of red blood.
• Diverticulosis: Small pouches in the colon wall can bleed, sometimes briskly and without pain. When those pouches become infected or inflamed it becomes diverticulitis, which adds fever and belly pain.
• Colon polyps: These growths on the colon lining can bleed and, over years, some can turn into cancer. Finding and removing them is a main goal of colonoscopy.
• Inflammatory bowel disease: Ulcerative colitis and Crohn's disease inflame the gut lining and often cause bloody, mucus-filled diarrhea along with cramping and urgency.
• Infections: Food poisoning and gastroenteritis can produce bloody diarrhea for a few days, especially with certain bacteria.

Upper digestive tract (often dark or tarry blood)

• Stomach ulcers: Open sores in the stomach or upper intestine are a leading cause of melena, especially in people taking regular pain relievers like ibuprofen or aspirin.
• Gastritis and esophagitis: Inflammation of the stomach or food-pipe lining can ooze blood. Long-standing acid reflux is a common driver.
• H. pylori infections: This common stomach bacterium is behind many ulcers and can be cured with antibiotics.

Other digestive conditions such as irritable bowel syndrome and celiac disease do not usually cause true bleeding on their own, but they can lead to straining, hard stools, or irritation that does. Your doctor sorts out which one fits your pattern.

When to Seek Emergency or Urgent Care

Most bleeding is minor, but some signs mean you should not wait. Knowing them can be lifesaving.

Call 911 or go to the emergency room now if you have:

• Large amounts of blood, repeated bleeding, or passing many clots
• Black, tarry stool (melena), which can signal heavy bleeding higher up
• Vomiting blood or material that looks like coffee grounds
• Feeling faint, dizzy, weak, or confused, or actually passing out
• A fast heartbeat, cold and clammy skin, or trouble breathing
• Severe or sudden belly pain along with the bleeding

These point to significant blood loss or a serious source that needs treatment right away.

See a doctor within a day or two (urgent, not 911) if you notice:

• Bleeding with fever, ongoing diarrhea, or vomiting you cannot keep down
• A clear change in bowel habits, unexplained weight loss, or constant fatigue
• Bleeding that keeps coming back over several days, even if each amount is small
• Any rectal bleeding if you are over 45 or have a family history of colon cancer

Blood in an infant's stool always needs same-day medical advice. In babies, it may come from a milk-protein allergy, a small fissure, or an infection; a pediatrician should guide the next step. Never wait it out on your own with a young child.

Relief and Self-Care

If your bleeding is light, painless, and clearly tied to something minor like hemorrhoids or hard stools, these steps can ease symptoms while you arrange a checkup. They do not replace a visit, and any new or repeated bleeding still needs a doctor's eyes.

Soften stools and stop straining

• Add fiber gradually: Aim for more fruits, vegetables, beans, and whole grains, or use a fiber supplement, to make stools easier to pass.
• Drink more water: Fluids keep stool soft and reduce straining that irritates hemorrhoids and fissures.
• Do not push or sit too long: Go when you feel the urge, and avoid lingering on the toilet, which raises pressure on anal veins.

Calm irritation

• Warm sitz baths: Soaking the bottom in warm water for 10 to 15 minutes a few times a day eases hemorrhoid and fissure pain.
• Over-the-counter creams: Short-term hemorrhoid creams or witch hazel pads can reduce itching and swelling.
• Gentle wiping: Use soft, unscented wipes or moistened paper to avoid further irritation.

Be careful with pain relievers

Regular use of ibuprofen, naproxen, or aspirin raises the risk of stomach bleeding. If you suspect an ulcer or have dark stools, talk to your doctor before taking any of those again, and ask whether acetaminophen is a safer choice for you. Track the color, amount, and timing of any bleeding so you can describe it clearly at your appointment.

How Blood in Stool Is Diagnosed

Your doctor's job is to find where the blood is coming from and rule out anything serious. The workup is matched to your age, symptoms, and how the blood looks.

When to See a Doctor and Which Specialist

Any blood in your stool is worth a conversation with a clinician, even when it stops on its own. Bleeding that is heavy, dark, repeated, or paired with pain, weight loss, or a change in bowel habits should be evaluated soon.

The specialist who handles blood in stool is a gastroenterologist, a doctor trained in the digestive system who can perform colonoscopy and upper endoscopy, diagnose the cause, and guide treatment. Your primary care doctor can do the first assessment and refer you, but the gastroenterologist is the one who looks directly at the gut lining and treats sources like polyps, ulcers, and inflammatory bowel disease.

If you are due for colon-cancer screening (generally starting at age 45) or have a family history of colon cancer or polyps, mention it. Screening can catch and remove polyps before they ever cause symptoms. The directory of digestive-health specialists below is sorted by state and city, so you can find a gastroenterologist close to home and book a visit.

Frequently Asked Questions

Medical disclaimer: This content is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition. If you have a medical emergency, call 911. Our editorial standards