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Crohn’s disease: Explain like I’m five

Crohn’s disease (CD) is an idiopathic chronic inflammatory disease of the gastrointestinal tract related to dysregulated mucosal immune response to commensal bacteria.

Wait. What? I thought this was an explanation for a five-year-old.

Let’s break it down.

Idiopathic: We don’t know what causes it.

Chronic: We can’t cure it.

Inflammatory: Red and swollen tissue, sometimes with ulceration (open sores)

Gastrointestinal tract: Humans are essentially donuts with sphincters. Your intestines are a long tube running from your mouth to your anus. See picture below.

Dysregulated: Not behaving normally

Mucosal immune response: The way the immune system reacts to surfaces that are exposed to the outside world (or semi-outside world in the human donut case).

Commensal bacteria: Friendly bacteria that live in our bodies.

Yup. I drew this.

Simply put: In Crohn’s disease the immune system doesn’t know which bacteria are supposed to be there and which aren’t. Because of that it attacks the gut and makes ulcers (sores). Crohn’s disease can affect anywhere from mouth to butt, but is most commonly seen in the small intestine or colon (see picture). These ulcers cause a bunch of symptoms including abdominal cramps and pain, diarrhea (possibly with blood or mucus), constipation, fever, weight loss, and urgency (needing to go to the toilet urgently). Crohn’s doesn’t just affect the GI tract, it’s also related to eye inflammation, arthritis and joint pain, skin rashes, anemia (low iron), and fatigue. Bowel obstructions are also possible due to the chronic inflammation.

The jejunum is the middle bit of the small intestine.
(Mild) inflammation in the jejunum.

While Crohn’s disease isn’t a mental health problem, stress can worsen symptoms and decrease your ability to deal with being sick. Many people find that their symptoms are worse after major life events like a break up, illness or death in the family, or stressful period at work. It’s important to remember that being stressed isn’t what causes you to develop Crohn’s disease. That said, keeping a handle on your mental health and looking after your mind as much as your body can help to tame some of your symptoms. People with Crohn’s disease are more likely to develop anxiety and depression and their anxiety and depression is often worse during times when their disease is active. It’s hard not to be anxious when you’re sick and don’t know if you’ll get better.

All of these symptoms can come and go. The time when symptoms are present is called a “flare” and when symptoms are absent it is said that the person is in “remission”. This doesn’t mean that the Crohn’s disease is cured and definitely doesn’t mean that the symptoms won’t come back. Sometimes people with Crohn’s may feel better (have fewer symptoms), but still have inflammation in their GI tract.

More fun facts about Crohn’s!

  • It affects men and women at roughly equal rates.
  • Tobacco smokers are twice as likely to develop Crohn’s disease as nonsmokers. People with Crohn’s who smoke are also more likely to have more severe inflammation and are more likely to need surgery.
  • Most people who develop Crohn’s disease start having symptoms in their early 20s to mid 30s.
  • Crohn’s disease is more common in urban areas than in rural areas.
  • The first symptoms of Crohn’s disease often come about after a stomach bug.

Secondary symptoms that no one tells you about

  • Always needing to know exactly where the nearest toilet is
  • Always carrying an extra pair of underwear (you never know when you might poop yourself)
  • Converting your nightstand into a pharmacy

What it isn’t

Crohn’s isn’t Ulcerative Colitis.

Ulcerative colitis is an inflammatory bowel disease (IBD) like Crohn’s disease. It differs in that ulcerative colitis only affects the large intestine (colon) and rectum and doesn’t usually cause fistulae (a tunnel running from one part of the intestine to another that shouldn’t be there).

Crohn’s isn’t Irritable Bowel Syndrome.

Irritable bowel syndrome (IBS) is a collection of symptoms that are similar to the ones that come with Crohn’s disease (abdominal pain, diarrhea, constipation), but it doesn’t cause intestinal inflammation. IBS isn’t life threatening and having it doesn’t mean that you’re more likely to get other bowel related disorders like colon cancer or IBD.

Crohn’s isn’t something you did.

When you are diagnosed with an incurable illness it’s hard not to wonder what you did to deserve it. It’s especially hard when people tell you that you just need to eat more turmeric, do hot yoga, or follow an all meat diet. You did not cause this and you do not deserve this.

How is it diagnosed?

Diagnosing Crohn’s disease can be a difficult process because the early symptoms are similar to many other illnesses (you can read my personal diagnosis story here). The process can be drawn out because they need to exclude so many illnesses (such as infections) and locate inflammation in nine metres (30 ft) of GI tract. When you first see your primary care physician they may refer you to a gastroenterologist (or gastrointestinal specialist) for further tests. There is no one single test that can diagnose Crohn’s disease.

Blood tests will be used to look for anemia and to measure the level of inflammation in your body (with a marker called c-reactive protein). A fecal (poop) sample may also be taken to look for infection and to measure the level of infection in your gut (with a marker called fecal calprotectin).

If your doctor suspects inflammation or just wants some more information about what is happening in your gut, they will probably want to get eyes up there. This can be done through a colonoscopy or sigmoidoscopy, which are both flexible tubes with cameras (scope) that go up your butt. Or a gastroscopy (also called an upper endoscopy) in which a similar scope goes into your GI tract through your mouth. A video capsule endoscopy, where you swallow a pill-sized camera that records images of your entire GI tract, is also sometimes used in the Crohn’s diagnosis process. Another way to look at the GI tract is through a CT scan, ultrasound, MRI, or barium x-ray (where a dye is swallowed and x-rays are taken). Because there is no single test to determine if someone has Crohn’s, doctors will take all the various tests into account along with your symptoms to determine whether you have Crohn’s.

How is it treated?

This is not a complete list, but includes some of the more common treatments.



Corticosteroids (like prednisone) reduce the inflammation in the GI tract. They are usually given in tablet form. These are often the first line of treatment for people diagnosed with Crohn’s disease alongside some of the other medicines on this list. Corticosteroids have fun side effects like insatiable hunger, mood swings, and water retention (moon face). They are also often very, very effective.


These are a class of medicine that help the body control inflammation. They come with side effects like headache, nausea, and rash, but many people tolerate them well. These medications are reasonably effective in treating mild to moderate Crohn’s disease.


Antibiotics like metronidazole and ciprofloxacin are sometimes used to treat Crohn’s. Side effects include nausea, a metallic taste in the mouth, and some tummy upset. It seems that antibiotics are sometimes helpful to get people with Crohn’s into remission, but that this benefit decreases the longer it is used.


Immunosuppressants like Azathioprine and 6-mp inhibit the immune response. Essentially they make your immune system react less. This is great for reducing inflammation, but also means that you’re more likely to get colds and flus. Other common side-effects include nausea, fever, rashes, and hepatitis. Use of immunosuppressants is also related to increased risk of cancer (lymphoma). However, this medicine can be very helpful in getting people with Crohn’s into remission and keeping them there.


Biologics are derived from human organisms. The biologics used to treat Crohn’s disease target specific aspects of the immune system to reduce inflammation. Some examples of biologics are etanercept (Enbrel), adalimumab (Humira), infliximab (Remicade), ustekinumab (Stelara), and rituximab (Rituxan). Like other drugs that change the way the immune system works, biologics have a number of side effects including injection site reactions and an increase in infections (like chest infections).


Some people may stop responding to medication that has kept their Crohn’s disease in check for a time while others have such severe inflammation in their gut that medication alone doesn’t keep it under control. For these people surgery might be necessary. In surgery for Crohn’s disease part(s) of the GI tract that are inflamed are removed and the intestines are reconnected without that part. This is called a resection. Even if the diseased parts are removed, inflammation can develop in other areas of the intestine after surgery.

Sometimes removing part or all of the colon is necessary. The surgeon will then create an artificial exit for waste to leave the body, called an ostomy. Instead of leaving through the anus, the waste will go through the artificial hole made by the surgeon and be collected in a bag. Having an ostomy can be temporary (it can help to give the intestines below the ostomy some time to heal) or permanent (as is the case if most of the colon or anus are removed). While this may sound unpleasant, ostomies are life saving procedures. This video has a fun explanation of how an ostomy is created.

Pain management:

For most people with Crohn’s disease pain is a constant companion. Learning how to manage pain is an important part of the treatment process. Pain can be managed with medications like acetaminophen or opioids (for severe pain), but non-steroidal anti-inflammatory (NSAID, e.g. aspirin or ibuprofen) medicines should be avoided as they have been shown to worsen Crohn’s disease symptoms. Some people find that cannabis oil lessens their pain and helps them to manage nausea. Non-substance pain treatment options can also be really helpful instead of or in addition to the substances mentioned before. Heating or cooling pads placed on the tummy or a warm bath can ease pain.

Pain management should always be discussed with your doctor. If you’re in pain, let them know!

Alternative treatments:


There is no one “Crohn’s disease diet”, but people with Crohn’s disease often find that certain foods make their symptoms worse. People’s experiences with Crohn’s and food vary greatly and something that sets off one person’s symptoms (e.g. raw vegetables) may be all another person can tolerate. Even so, many people swear by a variety of diets including the low FODMAP diet, low residue diet, specific carbohydrate diet, vegetarian or vegan diet, and Mediterranean diet.

Crohn’s disease can also reduce your body’s ability to absorb important nutrients. Because of this, it’s important to have frequent blood work to make sure that the levels of vitamins and minerals in your body are high enough.


Probiotics are food supplements that contain billions of commensal (friendly) bacteria. While scientists are currently going wild for the potential of probiotics in various medical treatments, there is no evidence that Crohn’s disease symptoms can be improved with probiotics. In fact, some recent studies have warned against taking probiotics before we know all of the possible effects.


The thought of having someone else’s poop in your body may seem a bit science fictiony and gross, but fecal microbiota transplants (FMT) use the same principle as probiotics — putting “good” bacteria in your gut to crowd out the bad bacteria. As with probiotics, there seems to be no solid evidence that FMT can alleviate symptoms of Crohn’s disease or decrease inflammation. That said, new studies are underway that will look at this potential treatment method in more detail so stay tuned.

Prognosis (how the disease usually progresses)

Because Crohn’s disease affects all layers of the intestinal wall and not just the surface, complications can occur.

Some of these complications include:

  • Strictures: if the gut wall becomes narrower or there is a blockage in the intestine.
  • Abscesses: boils
  • Skin tags: swollen bits of lumps of skin around the anus
  • Fistulae: tunnels running from one part of the intestine to another that shouldn’t be there
  • Fissures: tears in the lining of the anus
  • Malabsorption: when the body can’t take in nutrients because of, for example, inflammation
  • Malnutrition: when the body can’t absorb all the nutrients it needs through the gut
This is a cross section of the intestine. Crohn’s disease inflammation can go through all the layers. (I made a mistake, i tried to fix it).

The long-term prognosis for people with Crohn’s disease depends on a bunch of things, including how bad the inflammation is, where the inflammation is, whether they have had surgery, and if they are smokers. Overall, 80% of people with small intestine Crohn’s will undergo surgery for Crohn’s at least once in their lifetime.

In addition to the Crohn’s itself, the medication used to treat the disease also have some long-term consequences. Long term use of corticosteroids has been linked to osteoporosis development and immunosuppressants and biologics have been linked to (slightly) higher cancer risk.

Crohn’s disease is a complex illness that requires careful management. Patients will usually have to take several different types of medications, some which they need to inject themselves or have administered at a hospital or clinic. Many find that they need to change their diet and develop an exercise routine (that they can do even while in pain). With really good management, many people with Crohn’s do get into remission and live healthy(-ish) lives. Living well with Crohn’s requires deliberate effort.

What else you need to know about Crohn’s disease

If it isn’t yet abundantly clear, living with Crohn’s disease sucks. Here are some user reviews from Reddit users:

Crappy shipment schedule, product arrived unexpectedly. /u/cheweyfresh1
Poor service and defective product. Was made to believe purchase was a one time thing. Apparently now I’m subscribed. Can’t seem to unsubscribe anywhere. Not happy. /u/adamja92
Product integrates seamlessly with Netflix, but is incompatible with basic necessities such as vegetables and popcorn. /u/PlesiosaurusPancakes

What we don’t know yet

We don’t know what exactly causes it. We do know that it’s likely a combination of environmental factors (like smoking or diet), the bacteria that live in our gut, and genetic factors. Studies are underway to better understand what causes Crohn’s.


While this disease can be overwhelming, especially when you are first diagnosed, there are many treatment options available and tons of support to help you manage.

If you think you might have Crohn’s disease, here and here are sites with some more useful information. If you’re feeling lost, this subreddit is a great place to get online support.

If you know someone who has Crohn’s disease and want to know how you can best support them, check back here soon for a post on that very topic. Also, feel free to post questions/concerns below.

What is GutAI?

GutAI is a simple disease management app for Crohn’s patients. It helps you track medications, food, and symptoms. It also provides you with personalized insights and advice on how you can prevent flare-ups. It’s like a nurse who specializes in Crohn’s, available 24 x 7.

If you or anyone in your network has been diagnosed with Crohn’s, you should sign up for GutAI. We would love your feedback.

Compulsory disclaimer

I am not a doctor. I am a Crohn’s disease patient doing my PhD on Crohn’s disease. The information contained in this post is not medical advice. If you or someone you know has symptoms that could point to Crohn’s disease, please see your doctor.



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