If your colon could talk, it would probably say, “Please stop making me so inflamed.” Unfortunately,
different conditions can irritate the large intestine in different ways. Two of the more confusing ones
are eosinophilic colitis and ulcerative colitis. They can look similar on the
surfacethink diarrhea, cramps, maybe blood in the stoolbut under the microscope and in long-term
behavior, they are quite different.
Understanding the differences between eosinophilic colitis (EoC) and ulcerative colitis (UC) can help you
ask better questions, understand your test results, and work with your care team on a treatment plan that
actually fits what’s going on in your gut. This article breaks down each condition, how they overlap, and
how doctors tell them apartusing plain language, a little bit of humor, and zero colonoscopy photos.
Reminder: This article is for general information only and does not replace medical advice.
If you have persistent digestive symptoms, talk with a healthcare professional.
What are eosinophilic colitis and ulcerative colitis?
Eosinophilic colitis in a nutshell
Eosinophilic colitis is a rare inflammatory condition in which a specific type of white blood
cell, the eosinophil, builds up in the lining of the colon. Eosinophils are usually part of allergic
or parasitic responses. In EoC, they show up in large numbers in the colon, releasing inflammatory
chemicals that irritate and damage the tissue.
Eosinophilic colitis is part of a family of disorders called
eosinophilic gastrointestinal diseases (EGIDs), which also includes conditions like
eosinophilic esophagitis. EoC is uncommon, with estimated prevalence only a few cases per 100,000 people,
and it can occur in infants, children, and adults.
Common features of eosinophilic colitis include:
- Chronic or recurrent diarrhea (sometimes with blood or mucus)
- Abdominal pain or cramping
- Weight loss or poor growth in children
- Nausea or loss of appetite
- Personal or family history of allergies, asthma, eczema, or food reactions in some patients
EoC can be primary (no obvious outside cause) or secondary to something
else that attracts eosinophils to the colon, such as parasitic infection, certain medications, or other
inflammatory diseases. Part of diagnosing EoC is ruling those other causes out.
Ulcerative colitis in a nutshell
Ulcerative colitis is a much more common condition and one of the main types of
inflammatory bowel disease (IBD). In UC, the immune system chronically inflames the inner
lining of the colon in a continuous pattern that always starts in the rectum and may extend further up the
colon.
Unlike EoC, which is defined by eosinophils, UC typically shows a mix of inflammatory cells in the mucosa,
with characteristic microscopic changes like crypt abscesses and chronic mucosal damage. The inflammation
stays mostly superficial (mucosa and submucosa) but can still cause ulcers, bleeding, and significant
symptoms.
Common features of ulcerative colitis include:
- Frequent diarrhea, often with blood, mucus, or pus
- Urgent need to have a bowel movement
- Abdominal pain and cramping
- Rectal pain and bleeding
- Fatigue, weight loss, sometimes fever
- In children, possible delayed growth or puberty
UC is a lifelong, relapsing condition with periods of flare and remission. Over many years, it increases
the risk of colon cancer, especially if large portions of the colon are involved or inflammation has been
present for more than 8–10 years.
Key differences at a glance
| Feature | Eosinophilic colitis (EoC) | Ulcerative colitis (UC) |
|---|---|---|
| How common? | Very rare; only a few cases per 100,000 people. | Relatively common form of IBD worldwide. |
| Main immune cells involved | Eosinophils (allergy-type white blood cells) | Mixed inflammatory cells; not defined by eosinophils |
| Pattern in the colon | Often patchy; endoscopy can appear normal or mildly abnormal | Continuous inflammation starting in rectum and spreading proximally |
| Common symptoms | Diarrhea (sometimes bloody), cramping, weight loss; may be linked to food triggers | Bloody diarrhea, urgency, rectal bleeding, pain, fatigue |
| Typical triggers or associations | Food allergies, drug reactions, other causes of eosinophilia in some cases | Genetic susceptibility, immune dysregulation, environmental factors like microbiome changes |
| Diagnosis focus | High eosinophil counts on colon biopsies after ruling out other causes | Characteristic endoscopic and histologic IBD changes, continuous pattern |
| Core treatments | Dietary modification (often allergy-focused), steroids, sometimes other immune therapies | Aminosalicylates, steroids, immunomodulators, biologics, JAK inhibitors; surgery can cure |
| Long-term risks | Data still limited; chronic symptoms possible, but colon cancer risk is unclear | Increased colon cancer risk, severe flares, complications like toxic megacolon |
So, in simple terms: EoC is the rare allergic-type cousin with eosinophils; UC is the classic IBD that most
people mean when they say “colitis.”
Symptoms: where they overlap and where they differ
Both eosinophilic colitis and ulcerative colitis can show up with a very similar headliner symptom:
chronic diarrhea. That’s one big reason they can be confused. Both can also cause abdominal
pain, weight loss, and fatigue.
Symptoms that can overlap
- Loose stools or diarrhea
- Abdominal cramping or discomfort
- Unintentional weight loss
- Loss of appetite
- Signs of anemia (tiredness, paleness) if there is blood loss
Symptoms that lean more toward ulcerative colitis
- Frequent bloody diarrhea as a main symptom
- Strong urgency and “gotta go now” feelings
- Rectal bleeding and pain
- Symptoms that clearly improve with classic IBD medications like aminosalicylates
-
Extraintestinal issues, such as joint pain, eye inflammation, or skin rashes, which are more commonly
described with IBD.
Symptoms that can point toward eosinophilic colitis
- History of multiple food reactions, allergies, asthma, or eczema
- Symptoms that seem clearly related to certain foods
- Peripheral eosinophilia (high eosinophil count on blood tests)
- Patchy or subtle findings on colonoscopy despite significant symptoms
- Symptoms starting in infancy or early childhood without typical IBD patterns
That said, there is no “perfect” symptom combo that guarantees one diagnosis or the other. That’s why
doctors rely so heavily on imaging, lab work, and especially biopsies.
Causes and risk factors
What drives eosinophilic colitis?
Eosinophilic colitis is thought to be driven by immune responses that recruit eosinophils into the colon.
In primary EoC, this happens without an obvious external cause. In secondary EoC, the eosinophils are
responding to something elselike parasites, certain drugs, systemic eosinophilic syndromes, or even
underlying IBD.
Many people with EoC (especially children) have a personal or family history of allergies. In some cases,
specific foods appear to trigger symptoms, and elimination diets or allergy evaluations can play a central
role in management.
What drives ulcerative colitis?
Ulcerative colitis has a more familiar (but still not fully understood) storyline: it’s an
immune-mediated condition where the body’s immune system overreacts to gut contents,
microbiome changes, or other environmental triggers in genetically susceptible people.
Risk factors and contributors may include:
- Family history of IBD
- Immune and microbiome changes
- Certain environmental or lifestyle factors
- Past infections or antibiotic exposures, in some theories
UC is not caused by stress or diet alone, but both can influence the severity of symptoms and flares.
Emerging therapies, like TL1A-targeting antibodies, are being studied to better control this immune
overactivity.
Diagnosis: how doctors tell them apart
Because symptoms overlap, diagnosis is not “pick a label and go.” It’s more like detective work, with a
colonoscopy instead of a magnifying glass.
Step 1: History, exam, and lab tests
Your doctor will ask about duration and pattern of symptoms, blood in the stool, weight changes, and any
history of allergies or food triggers. Blood tests may look for anemia, inflammation markers, and elevated
eosinophils. Stool tests can help rule out infections and may show markers of inflammation.
Step 2: Colonoscopy and imaging
In ulcerative colitis, colonoscopy often shows continuous inflammation starting at the rectum, with redness,
friability (tissue that bleeds easily), and shallow ulcers.
In eosinophilic colitis, colonoscopy may be surprisingly subtle: the colon can look almost normal, or show
only mild edema, granularity, or patchy lesions. Because the visual changes can be minimal, biopsies are
crucialeven if everything looks “pretty good” to the naked eye.
Step 3: Microscopic evaluation (biopsies)
This is where the real differentiation happens:
-
In eosinophilic colitis, pathologists see markedly increased eosinophils in the colon
liningoften more than 15–20 eosinophils per high-power field in multiple segmentsafter other causes of
eosinophilia have been excluded. -
In ulcerative colitis, the pattern is that of chronic IBD: continuous mucosal
inflammation, crypt architectural distortion, crypt abscesses, and basal plasmacytosis, but not the same
dominant eosinophil signature.
Because colonic eosinophilia can also appear in infections, drug reactions, and even classic IBD, the
pathologist’s job is to decide whether the eosinophils are the main issue (EoC) or a side effect of
something else. That’s why your doctor and the pathologist need to share clinical context.
Treatment: different strategies for different colitis types
Treating eosinophilic colitis
Management of EoC often focuses on three pillars:
-
Identifying and removing triggers: If food allergies or sensitivities are suspected,
elimination diets or allergy testing may be used. In infants, eliminating cow’s milk protein and using
specialized formulas can sometimes dramatically improve symptoms. -
Controlling inflammation: Corticosteroids (oral or sometimes topical formulations) are
frequently used to reduce eosinophilic inflammation and relieve symptoms. Some patients may respond to
other immunomodulatory or biologic therapies, though evidence is still evolving. -
Treating secondary causes: If the eosinophilia is secondary to a parasite, medication, or
another disease, addressing that underlying problem is key.
Because EoC is rare, there are no universal, one-size-fits-all treatment guidelines. Care is usually
individualized and may involve a gastroenterologist, allergist, and dietitian.
Treating ulcerative colitis
Ulcerative colitis treatment is more standardized, with the goal of inducing remission (calming the flare)
and maintaining remission (keeping inflammation quiet). Common medications include:
-
Aminosalicylates (5-ASA): Often the first-line therapy for mild to moderate UC, delivered
orally and/or rectally. -
Corticosteroids: Used for flares when 5-ASA is not enough; not ideal for long-term use
because of side effects. -
Immunomodulators and biologics: Drugs that target immune pathways involved in UC
(anti-TNF agents, anti-integrin, anti-IL-12/23, and newer agents like TL1A antibodies under study). -
JAK inhibitors: Oral medications that block certain inflammatory signals in moderate to
severe disease. -
Surgery: Removing the colon and rectum (proctocolectomy) can effectively cure UC but is a
major decision and usually considered for severe or treatment-resistant disease.
Diet and lifestyle changes cannot cure UC, but eating a balanced diet, limiting aggravating foods during
flares, staying active, managing stress, and getting enough sleep can all help support symptom control and
overall health.
Long-term outlook and complications
Ulcerative colitis
Many people with UC can live full, active lives, especially with modern therapies. However, there are
important long-term considerations:
- Higher risk of colon cancer with extensive or long-standing disease
- Need for regular colonoscopy surveillance after several years of disease
- Potential complications like severe bleeding, toxic megacolon, or perforation during severe flares
- Extraintestinal issues (joints, skin, liver, eyes) that may need their own treatments
Eosinophilic colitis
Because EoC is rare and less studied, its long-term outlook is not as clearly mapped out. Many patients
improve significantly with the right combination of diet and medication, especially when secondary causes
are identified and treated. Some may have intermittent flares; others may experience more chronic
symptoms.
At this time, there is no strong evidence that primary eosinophilic colitis carries the same colon cancer
risk as long-standing ulcerative colitis, but data are limited, so ongoing follow-up with a specialist is
still important.
When to see a doctorand what to ask
Call your healthcare provider if you notice any of the following:
- Diarrhea lasting more than a few weeks
- Blood in the stool or black, tarry stools
- Unexplained weight loss or loss of appetite
- Ongoing belly pain that interferes with daily life
- Fatigue, dizziness, or signs of anemia
Questions you might bring to your appointment include:
- “Could this be ulcerative colitis, eosinophilic colitis, or something else?”
- “Do I need a colonoscopy and biopsies?”
- “Should I be evaluated for food allergies or other causes of eosinophilia?”
- “What lifestyle or diet changes make sense for my specific diagnosis?”
- “How often do I need follow-up visits or colonoscopies?”
The bottom line: don’t try to self-diagnose based on symptom lists alone. Your colon deserves better than
a guess.
Real-life experiences: living with eosinophilic colitis vs ulcerative colitis
Medical definitions are helpful, but if you’re the one running to the bathroom, you probably care just as
much about what life actually feels like with these conditions. While every person’s journey is
unique, certain themes show up again and again in people’s experiences with eosinophilic colitis and
ulcerative colitis.
The “diagnostic odyssey” phase
Many people describe a long period of “something is wrong, but no one can quite name it.” For someone who
ultimately has ulcerative colitis, that might start as occasional blood on the toilet paper, random cramps,
or a few “mystery stomach bugs” that never fully go away. Monthsor even yearslater, they end up in a
gastroenterologist’s office, finally get a colonoscopy, and suddenly the puzzle pieces click into place:
“You have inflammatory bowel disease.”
For eosinophilic colitis, the path can be even twistier. People may be told they have irritable bowel
syndrome, food poisoning, or “just stress.” Parents of infants with EoC sometimes bounce between different
formulas and pediatric visits before someone suggests that the baby’s diarrhea, blood in the diaper, and
poor weight gain might be related to eosinophils and food proteins. When a diagnosis finally lands, there’s
often a mix of relief (“I’m not imagining this”) and overwhelm (“Wait, what exactly is eosinophilic
colitis?”).
Food, fear, and figuring it out
Diet plays very different roles in UC and EoC, and people’s experiences reflect that. Someone with
ulcerative colitis might notice that certain foods make flares worsevery high-fiber salads, spicy takeout,
or greasy fast food, for examplebut they often can’t “cure” their UC through diet alone. Over time, many
people learn their own personal red flags, keep a list of “better tolerated” meals, and work with a
dietitian to avoid unnecessary restrictions.
For eosinophilic colitis, food can feel like both the problem and the solution. Some people are placed on
elimination diets, cutting out common culprits like dairy, soy, eggs, or wheat, then slowly reintroducing
them while watching for symptom changes. When a particular food is clearly tied to flares, finally
identifying it can feel like solving a mystery. At the same time, constantly worrying about every bite can
be exhausting. Many patients describe the emotional impact of feeling “afraid of food,” which is why
support from knowledgeable clinicians and (sometimes) mental health professionals is so important.
Life between the flares
One of the biggest goals for people with UC is to extend the “in-between” periodsthose months or years
when the disease is in remission and life feels relatively normal. With effective treatment, many people go
to work, travel, exercise, and socialize like anyone else. They might keep track of bathroom locations a
little more carefully than their friends, but they’re living their lives, not just their diagnosis.
For people with eosinophilic colitis, remission may mean stable bowel habits, fewer cramps, and the ability
to eat a reasonably varied diet without panic. Because EoC is rare and research is still evolving, patients
often become their own advocates and “mini-experts,” reading up on EGIDs, asking detailed questions at
appointments, and keeping careful symptom logs. Many find online or local support communities helpfulnot
only for practical tips, but also for the comforting realization that they’re not alone in dealing with a
condition most people have never heard of.
Mental health and support
Both eosinophilic colitis and ulcerative colitis can impact mental health. It’s hard to feel carefree when
you’re planning your day around bathrooms or worrying about the next flare. People often describe guilt or
frustration about canceling plans, missing school or work, or feeling like “the sick one” in the family or
friend group.
Over time, many patients develop a toolkit that includes practical strategies (carrying extra supplies,
knowing public restroom locations, packing safe snacks), emotional coping skills (mindfulness practices,
therapy, support groups), and clear communication with the people close to them. One recurring theme is
that life may look different than beforebut it is still very much a life. Hobbies, relationships, careers,
and dreams do not disappear just because you’ve picked up a chronic GI diagnosis along the way.
Whether your journey involves eosinophilic colitis, ulcerative colitis, or another condition entirely, the
most important takeaway is that you’re not expected to navigate it alone. Specialists, dietitians, mental
health professionals, and peer communities can all be part of your “care team,” alongside your own growing
knowledge about your body and what helps it feel as well as possible.
Conclusion: same neighborhood, different diseases
Eosinophilic colitis and ulcerative colitis both inflame the colon, but they do it in different ways and
usually for different reasons. EoC is the rare, eosinophil-driven condition that often overlaps with
allergies and may need allergy-focused work-ups and elimination diets. UC is the better-known form of IBD,
with continuous inflammation, well-established treatment pathways, and clear long-term surveillance
recommendations.
If you’re experiencing persistent GI symptoms, don’t try to guess which condition you haveor assume it’s
“just IBS” or “something I ate.” Talk with a healthcare professional, ask about appropriate testing, and
make sure biopsies are part of the conversation if symptoms are ongoing. Your colon might not be thrilled
about all the attention, but your future self will thank you.