Ulcerative colitis (UC) and eosinophilic colitis (EC) are both conditions that cause inflammation in the colon, with symptoms of diarrhea, abdominal pain and cramping. There are key differences in terms of their prevalence and causes.

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This article outlines some of the key differences between the two conditions.

UC is a form of inflammatory bowel disease (IBD) that causes inflammation in the large intestine.

EC is a rare type of eosinophilic gastrointestinal disease. It develops when a high number of eosinophils, a type of white blood cell that fights bacteria, appear in a person’s large intestine, causing inflammation.

Prevalence

UC is relatively common, with a prevalence of 156 and 291 cases per 100,000 people. Conversely, EC develops in 2.1 cases per 100,000 people.

Remission vs. relapse

Both UC and EC can occur in flares and with periods of remission, where symptoms range from acute, mild, severe, or completely gone.

While UC and EC both tend to be chronic, some people with EC experience only one flare of symptoms, whereas others may experience multiple.

Occurrence

A 2021 paper notes that the onset of UC tends to occur when the person is between 15 and 30 years old, with a second smaller peak occurring when the individual is between 50 and 70 years old.

EC may affect both adults and children and often presents before 6 months of age. EC in children typically resolves on its own.

While the exact causes are unknown, some factors contribute to UC, such as:

Research from 2021 suggests that a person’s immune system responding to viral or bacterial infection may trigger UC. The typical immune system causes temporary inflammation in a person’s body to help fight infections. In a person with UC, the inflammation remains after the immune system has cleared the infection, causing ulcers in the intestine.

Another review from 2016 also suggests genetic factors may contribute to UC. If someone has a first-degree relative with UC, their risk of also developing the condition is between 1.6% and 30%. However, people with no family history of UC can still develop the disease.

Health experts do not know the exact mechanism behind EC. However, a 2020 study found that in their sample of people with EC:

Both EC and UC have similar symptoms that involve:

Along with the intestinal symptoms, EC and UC symptoms can include:

When diagnosing UC, a doctor will ask about a person’s symptoms and if they have any family history of similar conditions. Laboratory tests of blood samples and stool samples can rule out the possibility of a bacteria, virus or parasite causing the symptoms.

If a doctor suspects UC, they may recommend performing a colonoscopy, which they perform as an outpatient procedure.

The doctor inserts a thin, flexible camera into the anus to examine the colon and look for signs of UC, such as inflammation and ulcers. They may also take a biopsy during the procedure.

Diagnosing EC involves similar diagnostic tests to UC, including blood tests to look for an eosinophil count and a colonoscopy to rule out other causes of the symptoms.

However, diagnosis of EC is not always straightforward, and doctors tend to base it on the exclusion of potential causes of irritation or high eosinophil counts in the colon. These causes include IBD, infections, and an adverse reaction to medications.

Treatment aims to reduce inflammation, manage symptoms and regulate the immune system’s response. To treat UC, a person may be under the care of a multidisciplinary team, including a gastroenterologist, dietitian and allergy specialist. Common treatment options include:

Medication for UC

Medication is usually the first-line treatment for UC. Doctors may prescribe aminosalicylates, which reduce inflammation in the lining of the gastrointestinal tract.

Other medications a doctor may prescribe include:

  • corticosteroids
  • immunomodulators
  • biologics
  • targeted small molecule medications

Diet for UC

Treatment for UC also focuses on diet, controlling inflammation and regulating the immune system.

While dietary therapy can be effective, UC will likely also require medication, or a combination of medications, in conjunction with diet changes.

Surgery for UC

A doctor may recommend surgery in cases of UC where medications are no longer managing the condition. Surgery for UC can involve removing the entire colon, called a colectomy.

A person with the condition may require emergency surgery if there is an obstruction or perforation in the colon.

Since EC is a rare condition that doctors do not fully understand, there is no clearly established set of treatment procedures as with UC. The treatment goal is to reduce the inflammation and damage due to the eosinophils.

Dietary therapy for EC

One treatment option for EC is eliminating potential trigger foods from a person’s diet. A dietitian can help individuals understand what foods to remove and how best to make the diet sustainable and nutritious.

Doctors may only identify a few foods causing the problem for some people, especially infants, typically milk or soy. Once a parent or caregiver removes these foods from a child’s diet, the EC typically resolves.

Medication for EC

Along with dietary therapy, the other main treatment method for EC involves corticosteroids, which aim to reduce swelling and inflammation.

Prednisolone is usually the first-choice corticosteroid for eosinophilic gastrointestinal diseases. It is effective in over 90% of cases.

In cases that do not respond to these first-line treatments, a doctor may consider using medications that manipulate the immune system. For example, a 2021 case study found that Montelukast, a leukotriene receptor antagonist for treating asthma, was an effective first-line therapy for EC with or without steroids.

Surgery is not often a treatment option for EC other than in severe cases with an obstruction in the colon that could be dangerous.

Since EC is very rare and difficult to diagnose, research on the effectiveness of such treatments is in short supply but shows promise in managing the condition.

EC in infants is often mild, with an outlook that is generally very positive. It will often spontaneously resolve, with children being able to tolerate implicated foods within a few years.

In adults, both UC and EC tend to become chronic. A person is likely to experience flare-ups and periods of apparent remission. Doctors may recommend routine surveillance involving follow-up colonoscopies or blood and stool tests in these cases.

Although UC and EC have very similar symptoms and both tend to be chronic, they are separate conditions that require slightly different treatments and management.

Although UC is a lifelong condition, many treatment options can help people manage their symptoms and improve their quality of life.

EC is a very rare condition, but it can resolve in cases in children by removing trigger foods. Ongoing research aims to better understand the condition and shows promising treatment options.