Crohn's disease (chronic inflammation of the intestine)

Crohn's disease (chronic inflammation of the intestine)
International Classification (ICD) K50.-


Crohn's disease (M. Crohn) is a chronic inflammation of all layers of the intestine, which has a relapsing course. Characteristic symptoms are abdominal pain in the right lower abdomen, which resembles that of appendicitis, in combination with diarrhea without blood.

In about 30 percent of patients, only the last part of the small intestine (illeum) is affected, and in about 25 percent, only the large intestine (colon) is affected. Approximately 45 percent of patients suffer from an infestation of both intestinal segments. However, other areas of the entire gastrointestinal tract may be equally affected.

Crohn's disease has a certain similarity to ulcerative colitis (chronic inflammation of the colon). However, this disease only affects the large intestine. Both diseases belong to the group of chronic inflammatory bowel diseases (CED).

In most cases, the disease appears for the first time between the ages of 15 and 34. Men and women are affected with equal frequency, whereas children are very rarely affected. In Germany, there are about five new cases per 100,000 inhabitants per year. To date, there is still no complete cure for Crohn's disease; there is only the possibility of alleviating the symptoms.


The causes of Crohn's disease are still unknown. However, it is assumed that a combination of hereditary, infectious, psychological, but mainly immunological factors play a role:

  • Some hereditary factors have already been researched that increase the risk for the disease.
  • The decisive environmental factors are still largely unknown. However, smoking is thought to have a negative effect on the risk of developing the disease.
  • Psychosocial stress, combined with predisposition, may also play a role in the development of the disease. In addition, stress can cause a renewed inflammation in patients.


In Crohn's disease, all layers of the intestinal wall are affected by inflammation in the sections of the intestine affected by the disease. However, healthy sections can always be found between the inflamed areas. If the inflamed areas heal, scars remain that lead to a narrowing of the intestine. These narrowed regions can result in intestinal obstruction.

In addition, Crohn's disease can lead to the formation of encapsulated pus accumulations (abscesses), as well as false connecting ducts (fistulas) to neighboring tissues or organs (such as other intestinal sections, bladder, abdominal skin). The inflamed sections can no longer fully reabsorb food components.

Depending on the degree of spread in the intestine, very different symptoms appear. Many patients show few symptoms for years, which is why the disease is sometimes only discovered very late.

Often the first symptom is fistulas in the anus area. Diarrhoea, abdominal pain and weight loss over a longer period than six weeks are also an alarm sign and indication of the disease. In addition, recurrent suppurations (abscesses) in the abdomen and intestines may also occur, which indicate Crohn's disease.

Attention should be paid to the following signs:

  • Diarrhea that lasts longer than six weeks (three to six times a day), usually with no blood present
  • Pain in the lower right abdomen, similar to appendicitis
  • Mild fever
  • Loss of appetite and weight
  • General feeling of illness

In addition, there are sometimes complaints that do not affect the digestive tract (extraintestinal manifestations). These include, for example, joint inflammation, skin changes such as erythema nodosum (nodular inflammatory thickening of the skin) or sores in the oral mucosa (aphthae), eye inflammation (such as uveitis, keratitis), osteoporosis and liver inflammation.

Crohn's disease either has a chronic course, i.e. symptoms that last longer than six months, or it progresses in relapses. In the relapsing course of the disease, the symptoms sometimes disappear completely, but reappear after a certain time. The probability of a new outbreak of the disease is about 30 percent after one year and up to 70 percent after two years.


The diagnosis begins with a detailed medical history, a family history and a physical examination. During the physical examination, the doctor checks, among other things, whether there is pain under pressure in the abdomen. He also examines the oral cavity and the anus of the patient to see if there are any characteristic signs of the disease.

A well-suited method for diagnosis is the colonoscopy (ileocolonoscopy). In the course of this examination, the doctor simultaneously takes a tissue sample (biopsy) from the suspicious intestinal segment. This sample is examined in the laboratory for possible inflammation, its nature and distribution. In addition, fistulas or intestinal constrictions (stenoses) can be detected. Furthermore, the stomach (gastroscopy) and the duodenum should be examined.

An ultrasound examination of the intestinal wall (sonography) is also very important, both as a screening check and as a follow-up. In addition, X-ray examinations can be performed with the aid of a contrast medium.

Changes in the small intestine can best be detected with magnetic resonance imaging (MRI) and computed tomography (CT). A blood analysis can be used to determine the CRP level, which can provide information about inflammation. A complete blood count is also performed.


The majority of patients suffering from mild or moderate Crohn's disease can be treated as outpatients. In some cases, however, hospitalization is unavoidable.

Some laboratory values can help in the choice of therapy. For example, the CRP value provides information about the course of the disease. This value can also be used to assess the risk of relapse. If there is an inflammatory process in the body, the amount of C-reactive protein (CRP) in the blood increases. In addition, the number and condition of the red blood cells (erythrocytes) are determined in order to detect any anaemia.

Therapy for an acute flare is divided into three stages, depending on the severity of the flare:

Low activity:

The first choice is local therapy with the corticosteroid (cortisone) budesonide (per day as a single dose or three single doses spread throughout the day).

If the affected person has no symptoms outside the digestive tract (extraintestinal manifestation), sometimes nutritional therapy or symptomatic therapy (such as agents for pain, cramps, and the diarrhea) may be sufficient.

Moderate activity:

In this case, budesonide or systemic (acting throughout the body) cortisone preparations are usually used. Sometimes nutritional therapy can also help. Antibiotics are also given if it may be a bacterial infection.

High activity: In this case, cortisone preparations are usually given, and possibly other medications that help suppress the immune system (such as azathioprine). If these drugs do not achieve the desired effect and surgery is not possible, there is also the possibility of administering antibodies against inflammatory factors (TNF antibodies).

Therapy in the resting phase (remission maintenance):

In a large proportion of patients, there is an alternation between episodes of disease and a symptom-free period (remission phase). Treatment during this symptom-free period is not absolutely necessary. Individual factors, such as the course of the disease, determine whether, how long and which drugs are used in such remission-maintaining therapy.


Since the reasons for the disease are often unknown, only the inflammation can be fought and the symptoms relieved. With the help of medication, a possible relapse can also be prevented over a certain period of time.

The following medications are used for Crohn's disease:

  • 5-ASA: Mesalazine or sulfasalazine develop their effect specifically either in the small intestine or only in the large intestine. These drugs are less effective in Crohn's disease than in ulcerative colitis, which is why they are only given in cases of mild disease progression.
  • Cortisone preparations: The endogenous hormone cortisone has an anti-inflammatory effect and curbs the activity of the immune system. Chemically synthesized cortisone preparations play an important role during an acute Crohn's disease attack. If the symptoms are only mild or moderate, or if the focus of inflammation is in the lower part of the colon, these preparations act directly on the spot (as suppositories or enema preparations). This results in fewer side effects. For more severe symptoms, tablets whose active ingredient is distributed throughout the body (systemic) are preferred.
  • Antibiotics: Antibiotics, such as metronidazole or ciprofloxacin, are mainly used when there is a bacterial infection, in addition to intestinal inflammation, or when it threatens to develop. The therapy is mainly used for fistulas. Fistulas are newly formed connections between the intestine and the surrounding tissue or organs. The danger of these fistulas is that they can cause infections by intestinal bacteria outside the intestine.
  • Drugs that suppress the immune system (immunosuppressants): These are used in severe cases of Crohn's disease. If cortisone preparations do not have the desired effect, if the side effects are too severe or if they cannot be taken for some other reason, immunosuppressants are used. Very often this involves the active substance azathioprine.
  • TNF antibodies: In very severe cases, anti-inflammatory drugs with the active ingredients Infliximab or Adalimumab are used (TNF antibodies). The active principle of these substances is that they bind messenger substances (cytokines) between the inflammatory cells and thus prevent the spread of the inflammatory reaction.

Surgical intervention:

Around 70 percent of those affected are not spared surgery within the first fifteen years of illness. This can also be the case despite drug therapy. Often, repeated operations may also be possible. During an operation, the following interventions take place:

  • The surgeon expands narrowed areas in the intestine with the help of a balloon.
  • Fistulas are closed and abscesses are cut open.
  • Sections of the intestine that are already heavily affected by inflammation are removed. This procedure is only performed if there are already serious complications, such as intestinal perforation, peritonitis or intestinal obstruction.

Proper nutrition:

Proper nutrition plays an important role in Crohn's disease patients, although there are no general guidelines for it. It is best to seek advice from the doctor on how to avoid deficiencies in vitamins, protein, iron or nutrients. During an acute episode, a high-fiber diet (astronaut food) often provides relief. Patients who suffer from particularly severe episodes receive nutrition through a drip to bring relief to the irritated bowel.

What you can do yourself:

If you already have Crohn's disease, you should watch for any sign that might indicate a worsening. Blood in the stool, new or different pain, and unexplained fever may be such signs.

During an acute Crohn's disease flare, it is essential to give the body adequate rest. Between relapses, normal work can be done.

There are no restrictions on diet. However, care should be taken that no deficiency symptoms occur due to the attacked intestine. This can be achieved with a healthy diet.

If there are intolerances to certain foods, these should be avoided. About 30 percent of patients cannot tolerate lactose (lactose intolerance). If this is the case, milk and milk products should be eliminated from the diet. Other Crohn's disease patients unfortunately suffer from fructose intolerance and must therefore avoid fructose.


The prognosis depends mainly on the extent of the disease. Crohn's disease is one of the diseases that cannot be cured. Nevertheless, the symptoms can be alleviated by the appropriate therapy. In addition, phases can often occur in which the affected person is completely free of symptoms.

Close self-monitoring on the part of the patient and regular check-ups are essential in order to detect and treat signs of a new episode of the disease as well as possible complications. In addition, the gastrointestinal tract should be regularly examined for malignant growths.

If properly treated, Crohn's disease patients often have the same life expectancy as healthy people. However, it is important to consult a specialist to adjust the therapy.


Since the trigger for Crohn's disease is still unknown, it is not possible to say how best to prevent the disease. Smoking and psychosocial stress are considered reliable risk factors that can be avoided.

A healthy lifestyle with sufficient sleep, regular exercise and a healthy diet can also have a positive effect on the symptom-free intervals.

Editorial principles

All information used for the content comes from verified sources (recognised institutions, experts, studies by renowned universities). We attach great importance to the qualification of the authors and the scientific background of the information. Thus, we ensure that our research is based on scientific findings.
Danilo Glisic

Danilo Glisic

As a biology and mathematics student, he is passionate about writing magazine articles on current medical topics. Due to his affinity for facts, figures and data, his focus is on describing relevant clinical trial results.

The content of this page is an automated and high-quality translation from DeepL. You can find the original content in German here.



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