Bleeding from your anus is almost always caused by something treatable, and the two most common culprits are hemorrhoids and anal fissures. Both are extremely prevalent, and neither is dangerous on its own. That said, rectal bleeding can occasionally signal something more serious, so understanding what your bleeding looks like and how it behaves helps you figure out your next move.
The Two Most Likely Causes
Hemorrhoids are swollen veins in the lower rectum or around the anus, similar to varicose veins in the legs. Internal hemorrhoids (the ones inside your rectum) typically cause painless bleeding. You’ll notice bright red blood on the toilet paper or dripping into the bowl, but it won’t hurt. External hemorrhoids, which sit under the skin around the anus, are more likely to cause pain, swelling, and itching. They only become seriously painful when a blood clot forms inside them, a condition called a thrombosed hemorrhoid, which creates sudden, intense pressure.
Anal fissures are small tears in the lining of the anus. They usually happen when you pass a hard or large stool, and they’re also common after childbirth. You’ll know the difference between a fissure and a hemorrhoid by the pain: fissures cause a sharp, searing sensation during a bowel movement, sometimes described as passing shards of glass. That intense pain can linger as a deep ache for minutes to hours afterward. Like hemorrhoids, fissures produce bright red blood on toilet paper, but pain is always part of the picture.
Quick Comparison
- Hemorrhoids: Dull ache or pressure, itching, painless bleeding if internal, possible soft lump near the anus
- Anal fissures: Sharp tearing pain during bowel movements, bright red blood, visible cut or crack in the skin around the anus
Other Possible Causes
Diverticular disease is the third major cause of rectal bleeding, especially in people over 40. Diverticula are small pouches that form in the wall of the colon. The blood vessels inside these pouches become fragile over time and can rupture, sometimes causing significant bleeding that comes on suddenly. Unlike hemorrhoids or fissures, diverticular bleeding tends to be heavier and is typically painless.
Inflammatory bowel conditions like Crohn’s disease or ulcerative colitis can also cause blood in the stool, usually alongside ongoing diarrhea, cramping, and fatigue. Infections, polyps, and, less commonly, colorectal cancer round out the list.
When Bleeding Is an Emergency
Most rectal bleeding is minor and stops on its own. But certain signs mean you need emergency care immediately. Call 911 or get to an emergency room if you have rectal bleeding along with any of these:
- Dizziness or lightheadedness when you stand up
- Rapid, shallow breathing
- Fainting or confusion
- Cold, clammy, or pale skin
- Blurred vision
- Nausea
These are signs of shock from blood loss. You should also get to an ER if the bleeding is continuous or heavy (soaking through pads or filling the toilet bowl), or if it’s paired with severe abdominal pain or cramping.
What About Colorectal Cancer?
This is the worry most people are really searching about, and the honest answer is that cancer is a rare cause of rectal bleeding compared to hemorrhoids and fissures. But it’s not impossible, and rates of early-onset colorectal cancer are climbing. About 10% of colon cancer diagnoses now occur in people younger than 50.
The absolute risk is still low. In your 20s, about 2.3 people per 100,000 are diagnosed. In your 30s, that rises to 6.4 per 100,000, and in your 40s, 19.2 per 100,000. Almost half of young people diagnosed with colon cancer had rectal bleeding as a symptom. That doesn’t mean rectal bleeding is likely to be cancer, but it does mean you shouldn’t automatically dismiss it as “just hemorrhoids” if you also have other symptoms: unexplained weight loss, persistent changes in bowel habits (new constipation or diarrhea lasting weeks), ongoing fatigue, or abdominal cramping that won’t go away.
The U.S. Preventive Services Task Force now recommends colorectal cancer screening starting at age 45 for people at average risk. If you have a family history of colorectal cancer or genetic conditions like Lynch syndrome, screening may start earlier.
What You Can Do at Home
If your bleeding is minor, bright red, and clearly tied to straining during a bowel movement, home care is a reasonable first step.
A sitz bath is the simplest treatment. Fill your bathtub or a plastic basin with 3 to 4 inches of warm water (around 104°F or 40°C) and soak the area for 15 to 20 minutes. You can do this three to four times a day. Plain warm water is all you need. Skip the Epsom salts, oils, or other additives unless your doctor specifically tells you to use them, because they can cause irritation. Pat the area dry gently afterward, never rub. If your pain worsens or the area becomes red and puffy after using a sitz bath, stop and call a doctor. If two or three sitz baths haven’t started to improve things, that’s also a sign you need professional input.
Increasing your fiber intake softens stool and reduces straining, which is the root cause of most hemorrhoids and fissures. Fruits, vegetables, whole grains, and beans are good sources, and an over-the-counter fiber supplement can fill gaps. Drink plenty of water alongside the extra fiber. Avoid sitting on the toilet longer than necessary, and don’t strain or push forcefully.
How Doctors Find the Source
If bleeding persists, recurs frequently, or doesn’t fit the pattern of a simple hemorrhoid or fissure, your doctor will want to investigate. The process typically starts with a physical exam and stool tests. Blood work can reveal whether you’ve lost enough blood to become anemic and can check how well your blood clots.
A colonoscopy is the most thorough tool for evaluating rectal bleeding. A flexible tube with a camera is inserted through the rectum so the doctor can view the entire large intestine. For bleeding limited to the lower area, a shorter version of this exam looks at just the rectum and the last section of the colon. These procedures can identify hemorrhoids, fissures, polyps, diverticula, inflammation, and cancer. In cases where the source of bleeding is harder to find, options include capsule endoscopy (swallowing a tiny camera in a pill-sized capsule) and CT imaging of the abdomen.
None of these tests are things you need to arrange on your own. A doctor will guide you to the right one based on your age, symptoms, and risk factors. The key is not to ignore bleeding that keeps coming back, changes in character, or shows up with other unexplained symptoms.