Crohn's disease and anal symptoms

This page compares two public descriptions of Crohn's disease, including what they say near the anus. It does not decide that a tear, drainage, or blood is Crohn's disease. ahem has not examined anyone and does not sell a treatment. A hemorrhoid and a fissure, as those pages separate them, are on hemorrhoids and anal fissures.

NIDDK last reviewed its symptoms page in July 2024. Opened October 29, 2026, it says doctors are not sure what causes Crohn's disease. It discusses an abnormal immune reaction, the environment, genes, and the microbiome. It says Crohn's disease sometimes runs in families, and that a parent or sibling with the disease may make it more likely. It says research has shown smoking may double the chance of developing Crohn's disease. That doubling is NIDDK's sentence, on the page checked October 29, 2026.

Mayo Clinic dates its page September 15, 2026. It calls Crohn's disease an inflammatory bowel disease that causes irritation and swelling, most often in the digestive tract, and says this can lead to belly pain, severe diarrhea, fatigue, weight loss, and malnutrition. It says there is no cure, and that therapies can reduce symptoms and sometimes bring long-term healing of inflammation. Inflammation most commonly affects the end of the small intestine and the beginning of the large intestine. It can skip sections of the intestine or be continuous.

NIDDK says the most common symptoms are diarrhea, cramping and pain in the abdomen, and weight loss. Its other symptoms are anemia, eye redness or pain, feeling tired, fever, joint pain or soreness, nausea, loss of appetite or vomiting, and skin changes such as red, tender bumps under the skin. It says symptoms may vary with the location and severity of the inflammation. Rectal bleeding is not on that list.

Mayo Clinic's symptom list is diarrhea, fever, fatigue, abdominal pain and cramping, blood in the stool, mouth sores, reduced appetite and weight loss, and pain or drainage near or around the anus from inflammation of a tunnel into the skin, which it calls a fistula. It says symptoms can range from mild to severe, usually develop over time, and sometimes come on suddenly. It also says symptoms often happen in cycles of active disease and periods with fewer symptoms. Outside the intestine, Mayo Clinic lists inflammation of the skin, eyes, and joints, inflammation of the liver or bile ducts, kidney stones, iron deficiency anemia, and, in children, delayed growth or sexual development.

The shared core is diarrhea, belly pain, and weight loss, with tiredness or anemia on both pages. Blood in the stool and drainage near the anus are on Mayo Clinic's list. They are not on NIDDK's symptom list opened the same day. A reader cannot use the missing line on one page to rule those findings out. The pages leave the diagnosis to a clinician.

Mayo Clinic's complication list includes a bowel blockage from scarring, ulcers anywhere in the digestive tract including the mouth, anus, and genital area, and fistulas. It says fistulas near or around the anal area are the most common kind. Fistulas inside the abdomen may cause infections and collections of pus, which it says can be life-threatening if not treated. It describes an anal fissure as a small tear in the tissue that lines the anus or in the skin around the anus, often linked to painful passage of stool, and says it may lead to a fistula.

A fissure page already says a tear on the side of the opening is more likely to be another condition, such as Crohn's disease, than a tear at the back or front. That clue is on when an anal fissure needs more tests. How the sources separate a fissure from a fistula, and which operations they name, is on an anal fissure and an anal fistula and surgery for an anal fistula. NIDDK's Crohn's symptoms page opened October 29, 2026 does not describe a fissure or a fistula. Mayo Clinic's sentences stay with Mayo Clinic.

Mayo Clinic says as many as 1 in 5 people with Crohn's disease have a family member with the disease, meaning a parent, sibling, or child. It says Crohn's disease can happen at any age and is more often diagnosed before age 30. It says cigarette smoking makes the disease more likely, leads to more serious disease, and raises the chance of needing surgery. It says nonsteroidal anti-inflammatory medicines, including ibuprofen, naproxen sodium, and diclofenac sodium, do not cause Crohn's disease, and that they can inflame the bowel and make the disease worse. NIDDK's doubling sentence for smoking is the one in the first section. Mayo Clinic does not print that double on the page opened today.

Mayo Clinic says Crohn's disease that affects more than one-third of the colon increases the risk of colon cancer after approximately eight years of disease. If the large intestine is affected, it says screening often starts 8 to 10 years after diagnosis and may be repeated every 1 to 5 years depending on the findings. If a person also has primary sclerosing cholangitis and colonic disease, it says screening is recommended every year starting at diagnosis. Those intervals are Mayo Clinic's, on the page dated September 15, 2026 and checked October 29, 2026. NIDDK's symptoms page does not print them. They are a conversation with a clinician, not a schedule to start alone.