What is Crohn's Disease?

Crohn’s Disease is one of the two major types of inflammatory bowel disease (IBD), the other being Ulcerative Colitis.

Both Crohn’s Disease and Ulcerative Colitis are believed to be autoimmune diseases, where the body reacts against its own tissues.

IBD affects over 28,000 people in New Zealand and is growing.

The main difference between the two conditions is that Crohn’s Disease can affect any part of the digestive tract, Ulcerative Colitis affects only the large bowel and the rectum.

Crohn’s Disease is a chronic (long-term) inflammatory disease and can cause inflammation in any part of the digestive system but mainly appears in the colon and small bowel. There is no cure, but treatment can ease your symptoms and help you enjoy a full, active life.

Crohn's can mimic the symptoms of bowel cancer and some reports suggest up to 15% of IBD patients go on to develop bowel cancer later in life.

Have a look at this quick 4-minute video which helps to explain Crohn's Disease...

Symptoms of Crohn's Disease

People with Crohn's Disease can have severe symptoms followed by periods of no symptoms that can last for weeks or years.

The inflammation causes uncomfortable symptoms and can result in severe damage to the digestive tract.

Some of the symptoms below can mimic those of bowel cancer symptoms..

  1. Chronic diarrhoea, often bloody and containing mucus or pus
  2. Weight loss
  3. Fever
  4. Abdominal pain and tenderness
  5. The feeling of a mass or fullness in the abdomen
  6. Rectal bleeding
  7. Nausea, vomiting
  8. Malnutrition, and vitamin deficiencies
  9. Tiredness, lethargy
  10. Bone loss (osteoporosis)
  11. Depression, anxiety (associated with coping with the condition)
  12. Stunted growth in children (which may occur many years before digestive symptoms appear)

Effects of Crohn's Disease

Crohn’s causes two types of complications:

1. ​Local - Which affects just the intestines

2. Systematic - Which affects the whole of your body

Complication Type 1 - Local

Local complications include...


This pocket of pus happens from bacterial infection. It can form on the walls of your intestines and bulge out. Or you might get one near your anus that looks like a boil. You’d notice swelling, tenderness, pain, and fever.

Bile salt diarrhoea:

Crohn’s disease most often affects the ileum, the lower end of your intestine. This part usually absorbs bile acids, which your body creates to help it absorb fat. If your body can’t process the fat, you could get this type of diarrhoea.


This is a painful tear in the lining of the anus. It can cause bleeding during bowel movements.


Sores or ulcers can turn into openings called fistulas that connect two parts of your intestine. They can also tunnel into nearby tissues, like the bladder, vagina, and skin.

Malabsorption and malnutrition:

Crohn's affects your small intestine, the part of your body that absorbs nutrients from food. After you’ve had it for a long time, your body may no longer be able to make the most of what you do eat.

Small intestinal bacterial overgrowth (SIBO):

Your gut is full of bacteria that help you break down food. When this happens higher up in your digestive tract than normal, you can get gas, bloating, belly pain, and diarrhoea.


These narrowed, thickened areas of your intestines result from the inflammation that comes with Crohn’s. They can be mild or severe, depending on how much of your intestine is blocked. Symptoms include cramping, abdominal pain, and bloating.

Complication Type 2 - Systematic

Systemic complications include...


Joint inflammation, which leads to pain, swelling, and a lack of flexibility, is the most common complication.

Skin problems:

These are the second most common systemic complication. Those most often linked to Crohn’s disease include:

Erythema nodosum:

These small, tender, red nodules usually show up on your shins, ankles, and sometimes your arms.

Pyoderma gangrenosum:

These pus-filled sores often follow an injury or other skin trauma. They often appear on your legs but can show up anywhere.

Skin tags:

These small flaps of skin are common in people with Crohn’s, especially around the anus or haemorrhoids.

Mouth ulcers:

You might hear them called canker sores. They form between your gum and lower lip or along the sides and bottom of your tongue.

Bone loss:

Medications like steroids can lead to bone loss, a condition known as osteoporosis.

Vitamin D deficiency:

If your body can’t absorb vitamin D because of Crohn’s damage to the small intestine or part of your small intestine has been removed, you’re less likely to be able to absorb calcium and make bone.

Eye problems:

Over time, the inflammation in Crohn’s, or sometimes the other complications that come with it, can affect your eyes.

Kidney problems:

These organs can be affected by Crohn’s because they play a role in processing waste and are located near your intestines.

Fatty liver disease:

When your body doesn’t process fats as well, they can build up in your liver. Steroids can help.


When Crohn’s affects the ileum (where your small intestine meets the large intestine), it can’t process bile salts, which help cholesterol dissolve. The cholesterol can form into stones that block the opening between the liver and the bile duct.


Chronic, long-term liver inflammation can result from Crohn’s disease itself.


Inflammation of the pancreas can result from both gallstones and medications. It can cause pain, nausea, vomiting, and fever.

Children and Crohn's

Crohn’s can start at any age. When kids get Crohn’s, parents are likely to notice two things.

1. Growth failure. Kids with Crohn’s are likely to be shorter and weigh less than those without. They may stop getting taller before symptoms start.

2. Delayed puberty. Kids with Crohn’s are likely to start puberty later. ​

The Children's Hospital of Wisconsin has put together some great cartoon videos to help explain to children what a colonoscopy or an endoscopy looks like and what they will go through when looking for signs of Crohn's Disease.

Click here to be redirected to this great video education content for children.

Camp Purple Live

Crohn's and Colitis NZ are an amazing support organisation for people with Crohn's Disease and Ulcerative Colitis.

Bowel Cancer Foundation works with this wonderful charity who have developed a camp for kids and teens called Camp Purple Live.​

The camp allows kids with inflammatory bowel condition the ability to interact with other kids facing similar challenges and is not made to feel different because of their disease.​

The camp gives children and teenagers a chance to experience fundamental elements of childhood – the ability to play outdoors, to learn independence, nourish self-esteem, challenge themselves physically, and be proud of their accomplishments and know they are not alone.

Click here to be taken to Youtube to watch a quick 10 minute on Camp Purple.

Charity Achievements

Key Milestones reached by Bowel Cancer Foundation Trust team.


Dollars distributed to help fund vital research and providing better patient outcomes


Bowel cancer survivors rehabilitated after gruelling treatment helping to reduce cancer re-occurrence


Bowel screening kits provided to Kiwi’s who do not qualify for free public screening to detect bowel cancer early


Loving families kept together for longer with help for immunotherapy treatments that help reduce tumours