Seeing blood in the toilet after you have had a bowel movement is more common than you might guess. There are multiple potential causes, ranging from from hemorrhoids to colon cancer. While rectal bleeding is more common in older patients, young people experience it as well. 

Regardless of age, it’s important to get it checked out promptly, says Hamita Sachar, MD, a Yale Medicine gastroenterologist. “Rectal bleeding is an alarm symptom that might signal a more serious underlying condition. Don’t put off seeing a doctor for it," she says.

Rectal bleeding usually appears as blood of varying colors (including bright red, maroon or black) in the stool. Rectal bleeding can be a symptom for a wide range of conditions, some more serious than others

Common causes of rectal bleeding include:

• Hemorrhoids:  These are pillow-like blood vessels located inside and outside the rectum, that can become swollen and start bleeding. Common during pregnancy, after childbirth and in people who suffer constipation, hemorrhoids are frequently the culprit when young people experience rectal bleeding.
• Bleeding lesions: Damage to the colon, rectum or anus, caused by infectious diarrhea, diverticulitis, or Crohn’s disease, can cause blood in the stool.
• Anal fissures: A tear in the lower rectum, typically the result of passing a hard stool, can cause bleeding. This condition usually heals within a few weeks.

Less common—and more serious—causes include:

• Colon cancer
• Diverticular bleeding
• Ulcerative colitis
• Crohn's disease

There are other possible causes for rectal bleeding as well. Proper diagnosis requires the expertise of a medical specialist.

Your doctor will take a medical history and perform an examination in order to determine which tests are necessary for diagnosis. Dr. Sachar asks patients when they first noticed the rectal bleeding. 

She says that blood connected with defecation is generally less severe than general bleeding. In the latter condition, there is risk of significant blood loss. Therefore, if you experience general rectal bleeding unrelated to a bowel movement, it’s important to get immediate attention. Typically a colonoscopy will be done to determine the best treatment option.

If you have other symptoms as well, such as dizziness, chest pain, or shortness of breath, these may indicate a more serious illness, such as cancer. 

Treatments vary depending on the cause of rectal bleeding.

Basic treatments for less serious conditions include encouraging a high fiber diet, and addressing constipation or diarrhea. If your rectal bleeding is caused by hemorrhoids, a variety of treatments are available, ranging from over-the-counter products like Preparation H, a pain-relieving ointment used to soothe hemorrhoids, to surgical procedures.

People with Crohn’s disease may be prescribed medication, such as corticosteroids or antibiotics, to manage their condition. Treatments for more serious disorders like colon cancer may require endoscopic or traditional surgery.

Though rectal bleeding is often easily diagnosed and treated, it’s comforting to know that Yale Medicine doctors are specialists who are knowledgeable about less common causes, including rare diseases. “Our specialists are sub-sub specialists,” says Dr. Sachar.

In addition, Yale Medicine also offers programs focused on treating particular gastrointestinal disorders, that can provide specialized care depending on your diagnosis. Patients with colon cancer, for example, might be referred to our world-renowned cancer specialists or colon and rectal surgeons. Patients with hard-to-treat hemorrhoids may be referred to Yale Medicine surgeons or the Yale Medicine Interventional Endoscopy team for treatment.