Why Is My Butt Bleeding? 7 Causes & When to Worry

Rectal bleeding usually signals something treatable — hemorrhoids, anal fissures, or constipation-related straining are behind most cases — but bright red blood on toilet paper or in the bowl always warrants attention to rule out more serious causes like inflammatory bowel disease or colorectal polyps.

Seeing blood when you wipe or noticing it in the toilet can be alarming, but understanding the common causes helps you know when to monitor at home versus when to call your doctor. This guide covers the most likely reasons for rectal bleeding in 2026, what the color and amount of blood indicate, and when the symptom requires urgent medical evaluation. We'll also address a related concern many pet owners search for: what it means when your dog or cat is bleeding from their rear end.

What Does the Color of Rectal Blood Tell You?

The color of blood you see provides important clues about where the bleeding originates — bright red typically means a lower digestive tract source near the anus, while darker blood suggests bleeding higher up in the colon or stomach.

Bright red blood on the toilet paper, dripping into the bowl, or coating the stool surface usually comes from the rectum or anus itself. This is the most common presentation and often indicates hemorrhoids, anal fissures, or minor trauma from hard stools.

Dark red or maroon blood mixed into the stool may indicate bleeding from the colon, such as from polyps, diverticulosis, or inflammatory bowel disease. This pattern warrants prompt medical evaluation.

Black, tarry stools (called melena) signal digested blood from the upper gastrointestinal tract — the stomach or small intestine — and require immediate medical attention.

7 Common Causes of Rectal Bleeding in Adults

Most rectal bleeding in adults stems from benign, treatable conditions — but some causes require medical intervention to prevent complications or rule out serious disease.

Do Hemorrhoids Cause Rectal Bleeding?

Hemorrhoids are the most common cause of rectal bleeding in adults. These swollen blood vessels in the rectum or anus can bleed when irritated by straining, hard stools, or prolonged sitting. You'll typically see bright red blood on the toilet paper or dripping into the bowl. Internal hemorrhoids are usually painless, while external hemorrhoids may itch or hurt.

"Hemorrhoids are very common. Nearly three out of four adults will have hemorrhoids from time to time." — Mayo Clinic Staff at Mayo Clinic

Can Anal Fissures Make Your Butt Bleed?

An anal fissure is a small tear in the thin tissue lining the anus. It typically causes bright red blood along with sharp pain during and after bowel movements. Fissures commonly result from passing large or hard stools, chronic diarrhea, or childbirth. Most heal within four to six weeks with increased fiber intake and proper hydration.

Does Straining from Constipation Cause Bleeding?

Chronic constipation forces you to strain during bowel movements, which can damage the delicate rectal tissue and aggravate existing hemorrhoids. Hard, dry stools physically scrape the anal canal on their way out. Addressing the underlying constipation — through fiber, fluids, and sometimes stool softeners — typically resolves the bleeding.

Also Read: Why Is My Poop Black? 7 Causes & When to Worry

Is Inflammatory Bowel Disease Behind Your Symptoms?

Conditions like Crohn's disease and ulcerative colitis cause chronic inflammation in the digestive tract, leading to bloody diarrhea, abdominal pain, and urgency. IBD-related bleeding tends to be persistent and accompanied by other symptoms like fatigue, weight loss, and cramping. Diagnosis requires colonoscopy and lab testing.

Could Colorectal Polyps Be the Cause?

Polyps are growths on the inner lining of the colon or rectum. While most are harmless, some can bleed and a small percentage may develop into cancer over time. Polyps often cause no symptoms, making routine colonoscopies important for adults over 45 or those with risk factors. When they do bleed, the blood may be bright or dark red depending on the polyp's location.

Do Diverticular Conditions Cause Rectal Bleeding?

Diverticulosis — small pouches that form in the colon wall — affects about half of Americans over 60. These pouches can bleed suddenly and painlessly, sometimes producing significant amounts of bright red blood. While alarming, most diverticular bleeding stops on its own, though evaluation is still necessary.

When Should You Worry About Colorectal Cancer?

Colorectal cancer can cause rectal bleeding, but it's typically accompanied by other warning signs: unexplained weight loss, changes in bowel habits lasting more than a few weeks, persistent abdominal discomfort, or a feeling that your bowel doesn't completely empty. Anyone over 45 should have regular screenings, and those with symptoms should see a gastroenterologist promptly.

"The U.S. Preventive Services Task Force recommends that adults aged 45 to 75 years be screened for colorectal cancer." — USPSTF at U.S. Preventive Services Task Force

Why Is My Dog Bleeding from His Butt?

Rectal bleeding in dogs usually indicates anal gland problems, intestinal parasites, colitis, or dietary indiscretion — but persistent or heavy bleeding requires prompt veterinary evaluation.

If you've noticed your dog bleeding from his bum or her butt, several conditions could be responsible. Anal gland impaction or infection is common, especially in smaller breeds, and may produce bloody discharge along with scooting behavior. Intestinal parasites like hookworms can cause bloody stool, particularly in puppies.

Colitis (inflammation of the colon) often causes dogs to pass small amounts of bright red blood with mucus, typically accompanied by straining and increased frequency. Dietary changes or eating something they shouldn't can also irritate the GI tract enough to cause bleeding.

More serious causes include hemorrhagic gastroenteritis (HGE), which produces sudden, profuse bloody diarrhea and requires emergency care, and tumors in older dogs.

Why Is My Cat's Butt Bleeding?

Feline rectal bleeding often stems from constipation, colitis, or anal gland problems — but because cats hide illness well, any visible bleeding warrants veterinary attention within a day or two.

Cats are prone to constipation, especially as they age or if they're dehydrated. Hard, dry stool can tear the delicate anal tissue, causing bright red blood on the surface of feces or in the litter box. Colitis from dietary sensitivity, stress, or infection produces mucus-covered stool with small amounts of blood.

Anal gland issues occur in cats too, though less commonly than in dogs. Parasites, inflammatory bowel disease, and polyps are other possibilities. Because cats often suffer in silence, behavioral changes like avoiding the litter box, crying during defecation, or excessive grooming of the rear end may be your only warning signs.

Any cat with rectal bleeding that persists beyond one or two episodes should see a veterinarian for examination.

When to See a Doctor for Rectal Bleeding

A single episode of minor bright red bleeding with an obvious explanation (like constipation) can be monitored — but recurring bleeding, large amounts of blood, or any accompanying symptoms require medical evaluation.

See your doctor within a few days if you experience:

• Bleeding that continues beyond one or two bowel movements
• Blood mixed into the stool rather than just on the surface
• Bleeding accompanied by pain, itching, or a lump near the anus
• Any change in bowel habits lasting more than two weeks

Seek immediate medical care if you have:

• Heavy bleeding or blood clots
• Dizziness, lightheadedness, or fainting
• Black, tarry stools
• Severe abdominal pain with bleeding
• Bleeding with fever

"Rectal bleeding that is heavy or that contains blood clots, or is associated with dizziness or fainting, requires immediate medical attention." — American Gastroenterological Association at Gastro.org

Also Read: Why Is My Poop Green? 7 Causes & What to Do About It

How to Reduce Rectal Bleeding at Home

For hemorrhoid or fissure-related bleeding, simple lifestyle changes often bring significant relief — but these measures won't help if the underlying cause is something more serious.

• Increase fiber intake gradually to 25–30 grams daily through vegetables, fruits, and whole grains
• Drink at least 8 glasses of water daily to soften stools
• Avoid straining — if nothing happens within a few minutes, get up and try later
• Use a stool (like a Squatty Potty) to elevate your feet during bowel movements
• Take warm sitz baths for 10–15 minutes several times daily for hemorrhoid relief
• Apply over-the-counter hemorrhoid creams or witch hazel pads
• Don't delay when you feel the urge to go

If home measures don't improve symptoms within two weeks, or if bleeding worsens, schedule an appointment with your doctor.

In Short

Rectal bleeding is common and usually caused by hemorrhoids, anal fissures, or constipation — conditions that respond well to increased fiber, hydration, and basic hygiene measures. However, blood mixed into stool, dark or tarry blood, persistent bleeding, or any accompanying symptoms like weight loss or bowel habit changes require prompt medical evaluation to rule out polyps, inflammatory bowel disease, or colorectal cancer. For pets, rectal bleeding signals anal gland issues, parasites, or colitis in most cases, but heavy or sudden bleeding in dogs or cats warrants same-day veterinary care.

What You Also May Want To Know

Why is my dog bleeding from his butt but acting normal?

Dogs can have minor bleeding from anal gland irritation, superficial rectal trauma, or mild colitis while still feeling well enough to eat, play, and behave normally. However, "acting normal" doesn't rule out a problem that needs treatment. If the bleeding continues beyond one bowel movement or recurs over several days, schedule a vet appointment — early intervention prevents minor issues from becoming serious.

Can hemorrhoids cause a lot of bleeding?

Yes, hemorrhoids can sometimes produce what looks like an alarming amount of blood — bright red blood dripping into the toilet bowl or soaking toilet paper. While the visual can be scary, hemorrhoid bleeding is rarely dangerous. That said, any heavy bleeding should be evaluated to confirm hemorrhoids are actually the cause and to rule out other conditions.

Why is my cat's butt bleeding after using the litter box?

The most common cause is constipation — hard, dry stool tears the anal tissue as it passes, leaving bright red blood in the litter box or on the stool surface. Colitis, anal gland problems, and parasites can also cause post-defecation bleeding. If your cat strains, cries, or avoids the litter box, or if bleeding happens more than once, see your veterinarian.

Should I go to the ER for rectal bleeding?

Go to the emergency room if you experience heavy bleeding or blood clots, black tarry stools, bleeding with dizziness or fainting, severe abdominal pain, or bleeding accompanied by fever. For minor bright red bleeding without other symptoms, an urgent care visit or appointment with your regular doctor within a few days is usually sufficient.

Can stress cause rectal bleeding?

Stress doesn't directly cause rectal bleeding, but it can contribute indirectly. Chronic stress often leads to poor dietary habits, dehydration, and constipation — all of which can cause hemorrhoids or fissures. Stress also exacerbates inflammatory bowel disease in people who already have the condition. Managing stress through lifestyle changes may help reduce GI symptoms overall.

Reviewed and Updated on May 30, 2026 by George Wright