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Colitis vs Crohn's Disease: What's the Difference

Colitis vs Crohn's Disease: What's the Difference?noresize

Crohn’s Disease and Ulcerative Colitis are two gastrointestinal conditions that fall under the umbrella of Irritable Bowel Disease (IBD). It can be challenging to differentiate between the two conditions, as they have many similarities.  They can impact people at any age and affect men and women equally.  Plus, the symptoms may appear similar at first glance.  Only a deeper review begins to tease out the differences between Ulcerative Colitis and Crohn's Disease.

The main difference is area of the digestive system each condition affects. Additionally, there are also slight differences in their:

  • Diagnostic criteria
  • Symptoms
  • Treatment

Read more about the differences between Crohn’s Disease and Ulcerative Colitis below.

Physiological Location for Colitis vs Crohn's

Ulcerative Colitis (UC): UC affects the large intestine, which is comprised of the colon and rectum. During a colitis flare, the innermost lining of your colon/rectum becomes inflamed and ulcers may form on the tissue surface. Ulcerative Colitis can also cause widespread inflammation in other parts of your body, including your eyes, skin, and joints.

Crohn’s Disease: Crohn’s disease can affect any part of the GI tract from the mouth to the anus, but most commonly affects the end of the small intestine (the Ileum). Crohn’s can also cause inflammation throughout other parts of the body such as the eyes, skin and joints. Unlike UC, Crohn’s inflammation can extend through the entire thickness of the bowel wall.  In this way, Crohn's symptoms can present anywhere in your body, whereas Ulcerative Colitis specifically impacts the large intestine.

Disease Symptoms

While there are many common symptoms of both Crohn’s and Ulcerative Colitis, there are also symptoms that are unique to each condition. As with all forms of IBD, symptoms vary from person to person. If you are experiencing 2 or more of these symptoms consistently, we recommend having an honest conversation with your doctor to begin diagnosis and treatment. The more common symptoms associated with each are listed below.

Ulcerative Colitis

    • Abdominal pain & discomfort: this feeling can range from moderate to severe
    • Blood or pus in stool: During a ulcerative colitis flare, ulcers may form on your large intestine.  These ulcers can become filled with pus or blood, which can pass through your stool
    • Fever: a fever can be caused by your body's normal inflammatory response.  However, in some instances, it can indicate a perforated colon or toxic megacolon, which requires immediate medical attention and a trip to the hospital.  If you experience regular fevers, absolutely reach out to your doctor immediately
    • Weight loss: likely to be a symptom of common ulcerative colitis side effects.  Your body's inability to digest food may lead vitamin deficiencies and malnutrition, which can influence unhealthy weight loss. Regular diarrhea can make the issue worse
    • Rectal bleeding: common side effect from a ulcerative colitis flare, caused by small ulcerations in the lining of your large intestines.  These ulcers can also present in your rectum.  If rectal bleeding causes you to feel faint, dizzy, or intense pain, call your doctor immediately
    • Frequent, recurring diarrhea: a common side effect of many inflammatory bowel diseases (IBD). If you experience recurring diarrhea even after increasing dietary fiber, reach out to your doctor and dietitian
    • Fatigue: fatigue can be the result by the nutritional deficiencies from frequent diarrhea and nutrient malabsorption in your colon.  You may also feel tired because you are dehydrated from frequent bowel movements 
    • Reduced appetite: Many times, the physical discomfort of a ulcerative colitis flare may 
    • Tenesmus: the feeling that you need to pass stools even though bowels are empty
    • Malnutrition: malnutrition happens if your body cannot properly digest your food and absorb its nutrients (small intestine).  Issues in your large intestine can interfere with absorbing water and electrolytes. In addition to other symptoms listed above, signs you may be malnourished include loss of muscle mass and general fatigue and weakness

Crohn’s Disease

    • Abdominal pain & cramping: there may be multiple causes of your Crohn's cramping.  Bowel blockages and fistulas may cause the cramps, which can be relieved with medications.  The narrowing of your colon, called a stricture, can also cause cramps... separately, sometimes stress may cause your symptoms.
    • Persistent Diarrhea: For both colitis and Crohn's, diarrhea can be a common symptom.  Diarrhea can be caused by many factors: supplementation (notably, iron), infection, diet and food sensitivities, malabsorption of fats, or even medication designed to improve your condition 
    • Fever: may develop as a side effect of your intestine being inflamed, or may be coincidental with an infection that your body is fighting.  Lastly, sometimes medication can cause fever
    • Rectal bleeding: bleeding is most concerning if you develop an anal fissure.  The good news is that fissured can be treated successfully without surgery
    • Constipation: similar to cramps, both strictures or not eating enough fiber can cause constipation if you have Crohn's
    • Urgent bowel habit: the general inflammatory response from Crohn's disease can trigger urgent bowel urges.  Treating your body's inflammatory response can also relieve the urges to go to the bathroom
    • Loss of appetite: this symptom affects 1 in 5 people with Crohn's Disease.  Many people experience lack of appetite because of their underlying discomfort and pain during a flare
    • Weight loss: weight loss has many causes, so it is important to work with your dietitian to determine the root cause of potential weight loss.  Factors include loss of appetite (from medication, discomfort, etc.), nutrient loss, malabsorption, medication, and even hormone imbalance
    • Fatigue: can be exacerbated by loss of appetite and cramping/discomfort.  In addition to adopting an improved Crohn's Diet, talk to your doctor about medication side effects.  Your doctor may also investigate if you have anemia. 
    • Night sweats: similar to fever, your night sweats are most likely to be associated with the body's natural inflammatory response.  If they persist after general treatment or medication (starting with Tylenol), consult your doctor
    • Changes in menstrual cycle: hormone levels, your general nutrition and nutrient absorption, and stress can all impact your menstrual cycle.  Treating your Crohn's / IBD is the best way to restore normal menstrual cycles
    • Skin conditions: skin problems are the second most common Crohn's complication that occurs outside of your GI tract.  You may experience bumps, sores, or blisters across your body
    • Joint pain: do not be alarmed if your Crohn's is associated with joint pain.  Joint pain occurs in ~55-70% of people with Crohn's, typically without inflammation (arthritis)
    • Fistulas: your doctor will be able to detect these.  The good news is that they can first be treated with medication.  There are a variety of associated symptoms and considerations, depending on where the fistula forms within your GI tract


Diagnosing IBD involves eliminating all other possible causes of your symptoms. There is no single diagnostic, so your doctor will typically conduct multiple tests to confirm diagnoses. Your diagnostic tools will likely include:

  • Ulcerative Colitis
    • Blood tests
    • Stool tests
    • Colonoscopy
    • Flexible sigmoidoscopy
    • X-Ray
    • CT scan
  • Crohn’s
    • Blood tests
    • Stool tests
    • Colonoscopy
    • CT Scan
    • MRI
    • Endoscopy


For both Crohn’s and Ulcerative Colitis, we recommend working with a team of professionals to help manage your condition. Your team should include your primary care doctor, GI doctor, dietitian, and therapist or psychiatrist (depending on your unique situation and needs). Having a clear treatment plan is key to helping keep Crohn’s and UC under control. Your treatment plan should be built around your disease severity, disease location, current medication, possible side effects of medication, and co-morbidities. The goal of IBD treatment is to achieve and maintain remission… we define remission as the absence of symptoms. Although Crohn’s and UC have many differences, the methods of treatment are similar for each

Diet Therapy 

Dietary changes for IBD depend on the stage of your condition. When your symptoms are active, we recommend a low fiber diet. Once remission is achieved, high fiber foods can be reintroduced slowly to support a high-quality diet. When working with a dietitian, your treatment plan will focus on dietary changes.  Below, I describe our general approach to dietary management for both Ulcerative Colitis and Crohn’s Disease.

  • Diet therapy for an active flare
    • When symptoms are active, the main goal of diet therapy is to reduce inflammation in your gut. To do so, you need simple, easy-to-digest food. This is where a low fiber diet comes in. Low fiber diets allow your body to heal/reduce inflammation and ultimately do less work to break down and digest food.
  • Dietary recommendations during remission
    • Once your body has healed, your dietitian will recommend reintroducing specific high fiber foods. High fiber foods tend to be more nutritious, so whenever possible, it’s important to incorporate these back into your diet. The low fiber approach is intended to be a temporary solution to heal inflammation.
    • Most people will have to consistently adapt their eating habits to the current state of their condition throughout their lifetime.
Low Fiber (Active Flare) High Fiber (Remission)

Foods to Eat:

  • Low fiber fruit: bananas, cooked fruit, canned fruit
  • Non-cruciferous vegetables: asparagus, potatoes, cucumbers, carrots
  • Refined grain products: white pasta, white rice, white bread
  • Lean protein: fish, chicken, lean pork, eggs, tofu

Foods to Eat:

  • Whole grains: oats, brown rice, whole wheat pasta, whole wheat bread
  • Legumes/nuts: beans, nuts, seeds
  • Fruits and vegetables: Reach for colorful, fresh fruits and vegetables. It can be helpful to remove the skin and seeds to avoid symptoms

Foods to Avoid:

  • Fruits with seeds and skins
  • Beans and legumes
  • Nuts and seeds
  • Whole grains
  • Cruciferous vegetables
  • Dairy
  • Spicy food
  • Caffeine
  • Alcohol
  • High-fat foods: fried food, red meat, fast food

Foods to Avoid:

  • Dairy
  • Spicy food
  • Caffeine
  • Alcohol
  • High-fat foods: fried food, red meat, fast food



Medications for IBD include prescription and non-prescription treatment. Some prescription medications include Biologics, Aminosalicylates, Antibiotics, Steroids, and Immunomodulators- all of which aim to suppress inflammation. Over the counter medications include antidiarrheals, pain relievers, and vitamin and mineral supplements such as iron, vitamin B12, and calcium and vitamin D.


Surgery is a last resort option for IBD treatment after medication and dietary intervention. Possible surgery options include removal of some or all of the small bowel, colon, and rectum.

Wrap Up

Although there are many overlapping characteristics of Ulcerative Colitis and Crohn’s disease, there are also many factors that make them unique. It is important to treat each person’s condition as its own unique case to ensure that your treatment plan is specific to you. If you suspect that you may have UC or Crohn’s, speak with your doctor to help with diagnosis, develop a treatment plan, and form a healthcare team.

Want to learn more about how to manage your Ulcerative Colitis or Crohn's Disease? Our team can help!

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