Crohn's Disease and the Immune System

Crohn's disease involves an abnormal immune response that causes ongoing inflammation in parts of the digestive tract. The immune system can react too strongly to material in the gut, allowing inflammation to continue and damage the bowel lining. Crohn's disease is a condition with periods of active symptoms and quieter periods, and the affected area can vary from person to person.

The immune system normally protects the body from harmful organisms while leaving healthy tissue alone. In Crohn's disease, immune activity in the digestive tract becomes poorly controlled. Inflammatory cells and chemical signals can remain active, leading to swelling and irritation in the bowel wall. This may affect digestion and the movement of food through the gut.

Possible symptoms include abdominal pain, diarrhoea, tiredness, reduced appetite, or unplanned weight loss. Symptoms can also come from other conditions, so a symptom by itself does not establish Crohn's disease. A clinician considers the pattern, examination findings, and test results together.

Keep a brief record of bowel changes, pain, appetite, energy, fever, and any foods or medicines that seem to affect your symptoms. Arrange a GP consultation if symptoms persist, recur, or interfere with eating, drinking, sleep, work, or daily activities. Assessment may include questions about your history, an examination, and tests such as blood tests; further digestive-tract tests may be arranged when needed.

Treatment aims to calm inflammation and maintain remission. Your clinician may discuss anti-inflammatory or immune-targeting medicines, nutrition support, and follow-up. Do not start, stop, or change prescribed treatment without medical advice, because symptoms and inflammation do not always change together.

Seek urgent medical help for severe or rapidly worsening abdominal pain, repeated vomiting, a swollen abdomen, fainting, confusion, or inability to keep fluids down. Prompt assessment is also needed for heavy rectal bleeding, black stools, or signs of dehydration such as very little urine and marked dizziness. These symptoms can signal a complication or another urgent problem, whether or not Crohn's disease has already been diagnosed.

Ask which findings support Crohn's disease, whether inflammation is active, which tests are appropriate, and how you will know whether treatment is helping. You can also ask what symptoms should trigger urgent contact and how to manage medicines during an illness.