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.