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Crohn’s disease: causes, symptoms, therapy, nutrition

by Josephine Andrews
Published: Last Updated on 367 views

Crohn’s disease is a chronic inflammation in the gastrointestinal tract, which usually progresses in phases. Typical symptoms are abdominal pain and severe diarrhea. There is currently no cure for Crohn’s disease. However, the symptoms can be positively influenced by medication and a corresponding lifestyle. Read here what exactly Crohn’s disease is, what causes the disease and how it is treated.

ICD codes for this disease:

ICD codes are internationally valid codes for medical diagnoses. They can be found, for example, in doctor’s letters or on certificates of incapacity for work.


quick overview

  • Description : chronic inflammatory bowel disease (IBD), which can also affect the rest of the digestive tract
  • Causes : still unclear, but the following factors may play a role: genetic predisposition, impaired intestinal barrier function, altered composition of the intestinal flora (intestinal microbiome), environmental factors (such as smoking)
  • Common symptoms : crampy abdominal pain, diarrhea, weight loss, tiredness, possibly fever, formation of abscesses and fistulas
  • Examinations : physical examination, ultrasound , colonoscopy , gastroscopy , endoscopy , possibly MRI and CT, blood and stool tests
  • Treatment : mostly with drugs like cortisone, mesalazine, immunosuppressive drugs (like azathioprine), biologics, anti-diarrheal drugs; Possibly surgery, psychotherapy
  • Prognosis : very different courses and degrees of severity, not curable

Crohn’s disease: description and causes

Along with ulcerative colitis, Crohn’s disease is one of the chronic inflammatory bowel diseases (IBD) . The main symptoms are cramping abdominal pain and diarrhea. The symptoms usually appear in phases . The patients can therefore be symptom-free for a longer period of time.

In principle, Crohn’s disease can affect the entire digestive tract – from the mouth to the anus. In most cases, however, only the last section of the small intestine and the transition to the large intestine are affected.

Crohn’s disease varies in severity from patient to patient. If the course is unfavorable, ulcers, constrictions (stenoses) and/or connecting passages (fistulas) to other organs form.

Crohn’s disease: causes

Crohn’s disease is accompanied by inflammation of the mucous membrane in the digestive tract – as mentioned above, preferably in the intestine. The inflammatory processes also spread to the deeper layers of the intestinal wall. Neighboring structures such as lymph nodes and the attachment of the intestine (mesentery) may also be affected.

The disease spreads in sections and not continuously in the digestive tract – healthy and diseased sections of the intestine alternate.

It is still not fully understood why some people develop Crohn’s disease. Presumably, several factors contribute to the development of the disease:

genetic factors

Crohn’s disease can be hereditary. Researchers now know numerous different genes that can be altered in chronic inflammatory bowel disease. One of them is the gene NOD2 (= CARD15). It contains the blueprint for a binding site (receptor) that regulates the release of endogenous antibiotics (defensins) in the small intestine. People who have one or more changes (mutations) in this gene have an increased risk of developing Crohn’s disease.

Impaired barrier function in the gut

A possible factor in the development of chronic inflammatory bowel diseases such as Crohn’s disease is a disrupted barrier function of the intestinal wall. On the one hand, the intestine must be permeable so that nutrients can get into the body, but on the other hand, it must also prevent pathogens from entering. If this balance is disturbed, problems arise. For example, bacteria that naturally live in the intestine can then penetrate the intestinal mucosa and thus call the immune system into action – various inflammatory cells are activated, which could contribute to the development of the disease.

Altered gut microbiome

The microorganisms that naturally live in the gut – collectively referred to as the gut microbiome (or gut flora) – may also play a role. Increased concentrations of a certain bacterium ( Myobacterium avium ssp. paratuberculosis , or MAP for short) were found in the intestines of patients. This germ triggers the so-called paratuberculosis or Johne’s disease in cattle – a disease with symptoms comparable to those of Crohn’s disease. Some researchers therefore believe that MAP causes Crohn’s disease in humans.

However, the changed microbiome composition could also be a consequence of the intestinal disease and not its cause. In addition, there are also studies in which no increased MAP concentrations were found in the intestines of Crohn’s disease patients.

environmental factors

Smoking increases the risk of developing Crohn’s disease. Other possible factors influencing the development of the disease are, for example, eating habits, hygiene and breastfeeding status.

Inflammation and risks in Crohn’s disease
In Crohn’s disease, various sections of the digestive tract become inflamed. The last sections of the small intestine and the large intestine are most frequently affected. In the event of an unfavorable course, fistulas and constrictions (stenoses) can also form.

Crohn’s disease: symptoms

Crohn’s disease progresses very differently. Some patients have very frequent and severe symptoms. Others have milder Crohn’s symptoms. The disease can even go undetected for years.

In most cases, Crohn’s disease takes a relapsing course – phases with more or less severe symptoms alternate with phases with few or no symptoms (remission phases). However, if a patient suffers from symptoms for more than six months, one speaks of a chronically active course .

Typical Crohn’s disease symptoms are:

  • Abdominal pain : The pain associated with Crohn’s disease is often cramp-like and occurs primarily in the lower right abdomen (this is where the last section of the small intestine is located). They are similar to the symptoms of appendicitis. However, the pain may also be felt in other abdominal regions or diffusely in the entire abdomen.
  • Diarrhea : Diarrhea usually occurs several times a day during a flare-up. As a rule, they contain no blood.
  • Weight loss : Many sufferers do not eat enough due to a lack of appetite and/or fear of abdominal pain. Many nutrients are also lost due to the diarrhea. As a result, patients often lose a lot of weight.
  • Tiredness, exhaustion, possibly fever : Due to the inflammatory processes, the patients feel tired and listless. Some also develop a high temperature or even fever. This is particularly the case with abscess formation (see below).
  • Abscesses and fistulas : Encapsulated accumulations of pus (abscesses) may form as a result of the inflammation. Connecting passages (fistulas) to other organs, into the abdominal cavity or to the outside can also develop. They often occur in the anal area and are often a first indication of Crohn’s disease.
  • Deficiency symptoms : Inflamed sections of the small intestine can no longer absorb nutrients as well. Nutrients are lost as a result of the diarrhea. All in all, deficiency symptoms can develop, eg skin changes (due to zinc deficiency ) or aphthae. Long-term calcium deficiency can also trigger osteoporosis.

Possible effects and complications

When the inflamed sections of the intestine (in the meantime) heal, scars often form . In severe cases, this can result in an intestinal blockage (ileus) that requires surgery.

Sometimes Crohn’s disease also affects organs outside the intestine ( extraintestinal involvement ). Possible consequences and complications include:

  • Fatty liver, chronic liver inflammation (chronic hepatitis), jaundice (icterus), liver cirrhosis, abscesses in the liver
  • Gallstones, bile duct infection, gallbladder cancer, bile duct cancer
  • Kidney stones
  • brownish lumps on the lower legs, painful skin sores
  • Drumstick fingers , white discoloration of the nails
  • Joint inflammation, joint pain, Bechterew’s disease
  • Iris inflammation, sclera inflammation, corneal inflammation, conjunctivitis
  • Anemia, blockage of blood vessels by blood clots (thrombosis)
  • vascular inflammation
  • Inflammation of the sac around the heart (pericarditis)
  • Deposition of protein in various organs (amyloidosis)
  • Overactive thyroid (hyperthyroidism)

In addition, chronic diseases such as Crohn’s disease represent a psychological burden for those affected. Many patients withdraw from social life and suffer from depressive moods. Some even develop mental disorders (such as anxiety or compulsive behavior).

Crohn’s disease: treatment

Crohn’s disease has not yet been cured. However, the treatment can slow down the inflammatory processes, alleviate the symptoms and delay relapses. When planning therapy, the doctor takes into account which sections of the digestive tract are inflamed and how severe the disease is. In this way, each patient receives treatment that is individually tailored to their needs.

Crohn’s disease is usually treated with medication, with several medications often being used together (combination therapy). In severe cases, an operation can be useful.


Crohn’s disease is all about getting the inflammation under control and relieving the symptoms. Drugs that have an anti-inflammatory effect or change or dampen the activity of the immune system are used for this purpose. If necessary, other medicines are also given (eg against diarrhea). The following active ingredients or groups of active ingredients can be used in Crohn’s disease treatment:

corticosteroids (“cortisone”)

Cortisone preparations such as prednisolone or prednisone have a strong anti-inflammatory effect. They are usually administered as tablets or capsules, sometimes also as an infusion , so that they can take effect throughout the body (systemic cortisone therapy). The dosage depends on the severity of the inflammatory activity.

Corticosteroids are given when the disease flares up, usually for several months. However, experts advise against long-term systemic cortisone therapy. The reason for this is the possible side effects of longer or higher doses of use (eg weight gain, “full moon face”, increased blood sugar and blood lipid levels, increased susceptibility to infections, increased risk of osteoporosis).

The cortisone preparation budesonide acts primarily in the intestine and is hardly absorbed by the body. Therefore, it triggers fewer side effects than other cortisone preparations. Budenoside capsules are prescribed when Crohn’s disease affects only the lower part of the small intestine and the appendix, but no other parts of the intestine or the rest of the body.


Mesalazine (5-aminoslicylic acid, 5-ASA) also has an anti-inflammatory effect, but less effectively than cortisone preparations. It is better tolerated for that. Mesalazine is used for mild illnesses – sometimes over a longer period of time to prevent the inflammation from flaring up again.


Immunosuppressants down-regulate the activity of the immune system and are used in the long-term treatment of Crohn’s disease. Sometimes they are also used in combination with cortisone preparations, for example in the case of a chronically active course of the disease.

Immunosuppressants commonly used in Crohn’s disease therapy are azathioprine and mercaptopurine. Another representative is methotrexate – an active ingredient that is also used in cancer therapy (as a cytostatic = agent that inhibits cell growth).

Corticosteroids also have an immunosuppressive effect, but are primarily used in Crohn’s disease therapy because of their strong anti-inflammatory properties.


For some patients, Crohn’s disease treatment also includes so-called biologics. These are drugs made by living organisms (such as bacteria). They can be given for severe flare-ups when cortisone is not helping enough. In addition, biologics are used for long-term treatment – instead of or together with immunosuppressive drugs.

Some examples of biologics used in Crohn’s disease:

TNF-alpha antibodies (eg infliximab, adalimumab) are so-called monoclonal antibodies and have an anti-inflammatory effect: they specifically block a specific component of the immune system – the inflammatory messenger tumor necrosis factor (TNF). That is why they are also called TNF-alpha blockers. The drugs are given as an IV or injection under the skin. TNF-alpha antibodies are used, for example, when high inflammatory activity cannot be controlled with cortisone. They are also often prescribed to patients with stubborn fistulas.

Ustekinumab is also a monoclonal antibody. It blocks the inflammatory messengers interleukin 12 and 23, which also results in an anti-inflammatory effect. The drug can be prescribed when TNF-alpha blockers are not working adequately.

Vedolizumab – another anti-inflammatory monoclonal antibody – attaches to a specific protein on the surface of certain immune cells (lymphocytes). As a result, these can no longer migrate from the blood into the intestinal tissue and cause inflammation there. Vedolizumab is given as an infusion. It can also be given when other medications do not work well enough to control the inflammation of the bowel.

Other medications

Depending on what is needed, the doctor will prescribe other medications for Crohn’s disease, for example anti- diarrheal medication (eg loperamide) against accelerated defecation or antispasmodics (eg butylscopalamin) against abdominal pain. If accumulations of pus (abscesses) or fistulas have formed, the patient is usually given antibiotics (eg metronidazole ). Nutrient preparations or nutrient solutions (formula diets) may be necessary if sufficient nutrient absorption is prevented by severe inflammatory processes or constrictions in the intestine.

Crohn’s disease: surgeries

Surgery is usually necessary for Crohn’s disease when complications arise, such as:

  • intestinal perforation
  • Bowel obstruction or permanent narrowing of the bowel (intestinal stenosis)
  • severe intestinal bleeding
  • Inflammation of the peritoneum (peritonitis)

Abscesses or fistulas between the intestine and bladder often have to be treated with surgery.

In severe cases of Crohn’s disease, severely inflamed sections of the intestine can be surgically removed. However, the disease cannot be cured in this way – the inflammation can reappear later in other places.

Around 70 percent of all Crohn’s disease patients have to undergo surgery within 15 years of diagnosis.

Crohn’s disease: nutrition

There is no evidence that a special diet helps with Crohn’s disease. However, a light full diet (formerly known as a basic gastroenterological diet) is recommended during symptom-free or symptom-poor phases. It cannot heal gastrointestinal diseases such as Crohn’s disease, but it can relieve the digestive tract and the metabolism. This can prevent non-specific intolerances such as pressure, a feeling of fullness or flatulence.

The light full diet is not only recommended for chronic inflammatory bowel diseases (in remission phases = phases between flare-ups), but also for irritable bowel syndrome, non-specific food intolerance, stomach and duodenal ulcers and uncomplicated liver and gallbladder diseases.

Light whole food concept

The light full diet is a wholesome, balanced diet that provides the body with all the nutrients it needs in sufficient quantities. However, if there is a proven nutrient deficiency (eg iron deficiency), the doctor treating you can also prescribe a suitable nutrient preparation.

As with the “normal” full-fledged diet, the recommended nutrient composition for the light full-fledged diet is :

  • 50 to 55 percent carbohydrates
  • 30 percent fat
  • 10 to 15 percent protein

In contrast to the “normal” full diet, however, the light full diet does not include food and drinks, which experience has shown are often poorly tolerated in gastrointestinal diseases . These include, for example:

  • Whole milk and full-fat dairy products, cream and sour cream with over 20% fat, spicy and fatty cheeses (45% fat), mold cheese (like Gorgonzola, Roquefort)
  • fatty, smoked, salted and seared meat, fatty and smoked sausages
  • fat soups and sauces
  • fatty fish (such as eel, herring, salmon), smoked fish, pickled and/or preserved fish and fish products
  • hard-boiled eggs, mayonnaise
  • larger amounts of oil, butter, regular margarine, lard and tallow
  • fresh bread, coarse wholemeal bread, fresh or fatty baked goods (such as cream cake, puff pastry, fat baked goods)
  • Roasted and fried potato dishes (French fries, fried potatoes, etc.), potato salad with bacon, mayonnaise or lots of oil
  • generally foods that have been seared, roasted, fried, or stir-fried with bacon and onions
  • Difficult to digest and flatulent types of vegetables (eg cabbage, onions, leeks, peppers, cucumbers, legumes, mushrooms), salads prepared with mayonnaise or fatty sauces
  • Unripe fruit, raw stone fruit, nuts, almonds, pistachios, olives, avocados
  • Chocolate, pralines, nougat, marzipan, toffee etc.
  • larger amounts of sugar
  • Larger amounts of salt, pepper, curry powder, paprika powder, mustard , horseradish, onion or garlic powder, hot spice mixtures
  • Alcohol, carbonated drinks (like soda, cola), iced drinks

Keep in mind that everyone has different sensitivities to certain foods and drinks. For example, some Crohn’s disease patients can consume small amounts of whole milk or a candy bar without any problems, while others react with symptoms. Try out which products you tolerate and in which amounts!

When it comes to grains and grain products, whole grains should be preferred and white flour avoided. Whole grains provide the body with a lot of fiber, which supports digestion.

Caution: If Crohn’s disease patients have extensive constrictions (stenoses) in the intestine, the diet should be low in fiber!

General nutrition tips

  • Eat several small meals rather than a few large ones.
  • Take your time eating and chew each bite thoroughly.
  • Don’t eat too hot and not too cold, not too sour and not too spicy.

nutrition during a flare-up

During an attack, the stomach and intestines need special protection. Most patients then tolerate a light, low-fiber diet. Purifying the food can also have a relieving effect. In the event of a severe flare-up, temporary artificial nutrition via drips may also be useful so that the digestive tract can calm down.


Constant toilet visits, abdominal pain, fatigue – in severe cases, Crohn’s disease has a massive impact on a patient’s quality of life and self-esteem. Some sufferers even develop psychological disorders such as depression or anxiety disorders.

Psychotherapy can help to deal with the stress better and to develop a positive attitude towards life and a solid self-image despite the illness.

As part of cognitive behavioral therapy , the patient questions and corrects negative thought patterns and practices new behaviors. Since stress can also worsen the symptoms, the patients learn strategies that help them to avoid unnecessary mental stress.

stress reduction

Patients with Crohn’s disease benefit from learning a relaxation technique. In this way, stress can be reduced, which can have an unfavorable effect on the course of the disease. Examples of helpful methods are:

Crohn’s disease: investigations and diagnosis

There are several steps to be able to diagnose Crohn’s disease. It starts with a detailed doctor-patient discussion to collect the medical history (anamnesis). Among other things, the doctor asks what symptoms the patient has and when they first appeared. He also asks if there are cases of chronic inflammatory bowel disease (Crohn’s disease, ulcerative colitis) in the family. Various investigations follow the discussion.

Physical examination

During a physical exam, the doctor feels the patient’s abdomen and checks for tenderness. He also examines the oral cavity and anus for signs of illness such as fistulas.


Inflammatory thickened intestinal walls, constrictions, fistulas and abscesses can be detected with an ultrasound device. However, changes in the mucous membrane can only be found with an endoscopic examination (see below).

A doctor can also use ultrasound to regularly check the course of Crohn’s disease.


The colonoscopy is the most important examination for diagnosing Crohn’s disease. The doctor carefully inserts a flexible endoscope – a thin tube with a tiny camera and a light source at the tip – through the anus into the intestine. This allows him to take a closer look at the intestinal mucosa.

The doctor can also insert fine instruments into the intestine via the endoscope, for example to take a tissue sample ( biopsy ). This is examined more closely in the laboratory for pathological changes. Constrictions (stenoses) and fistulas can also be detected during the colonoscopy and, if necessary, treated immediately.


During gastroscopy ( gastroscopy ), an endoscope is inserted through the mouth into the stomach – up to the transition to the first section of the small intestine (duodenum). In this way, the doctor can check whether there are also sources of inflammation in the upper digestive tract.

Capsule endoscopy

In unclear cases, the doctor also carries out other endoscopic examinations – such as capsule endoscopy. The endoscope here is a small capsule the size of a pill and is swallowed by the patient. The integrated small camera with a light source records images of the inside of the intestine on its way through the digestive tract and sends them wirelessly to sensors attached to the outside of the patient’s body. A recorder worn on the belt stores the data. The capsule is then excreted naturally (in the stool).

MRI and CT

Magnetic resonance imaging (MRI) can also be used to examine the intestine more closely for pathological changes. In addition, fistulas and abscesses can be detected and displayed in detail – just like with computer tomography (CT).

blood and stool tests

If there is severe inflammation somewhere in the body, this is reflected in certain blood values: the C-reactive protein (CRP), the white blood cells ( leukocytes ) and the blood sedimentation rate (ESR) are then usually increased. These parameters therefore act as non-specific signs of inflammation.

Blood tests can also indicate nutrient deficiencies that have developed as a result of chronic intestinal inflammation – such as a lack of zinc , calcium, vitamin B12 , folic acid or iron.

Other blood values ​​​​(such as kidney or thyroid values) may be changed if Crohn’s disease has also affected organs other than the intestines.

Stool tests are used to rule out other causes of frequent diarrhea with abdominal pain (such as bacterial infections).

Crohn’s disease: course of the disease and prognosis

There is no complete cure for Crohn’s disease. The course of the disease varies greatly from patient to patient and cannot be predicted. While some patients are completely symptom-free for a long time or only have minor symptoms, others often experience recurring, severe phases of the disease or have a chronic course of the disease.

As an affected person, however, you can do a few things yourself to reduce the severity of your symptoms and prolong the symptom-free phases:

  • Take the prescribed medication consistently.
  • Get enough sleep.
  • Relax regularly.
  • Move a lot.
  • Eat what is good for you. But make sure you eat a balanced diet – malnutrition can aggravate the clinical picture or even encourage relapses (flare-ups)!
  • Consult your doctor immediately if you feel that a new flare-up is imminent (eg with increased abdominal pain). If necessary, he can adjust your medication and thus counteract the flare-up or identify and treat any complications at an early stage.

Also, get regular screening for colon cancer – people with Crohn’s disease have a slightly increased risk of developing a malignant colon tumor.

With proper treatment, life expectancy for people with Crohn’s disease is normal.

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