CHAPTER 04 · THE BASICS

Symptoms & Flare-Ups

No two cases of ulcerative colitis look exactly the same. Here’s what symptoms can feel like, what a flare-up is, and when to reach out to your team.

Ulcerative colitis (UC) symptoms can vary widely, depending on where the colon is inflamed and how severe this inflammation is. Since the inflamed area can’t absorb water (one of its main functions), diarrhea is common. The more inflamed the colon is, the more likely it is that bleeding will occur, leading to bloody diarrhea (red or dark red in color).

Common Symptoms

🚽 Gut & bathroom

Recurrent diarrhea (may be bloody, with mucus or pus)
Urgent need to go
Frequent bowel movements
Tenesmus (feeling like you need to go even though there’s nothing left)
Abdominal pain (often cramping)

💪 Body & energy

Low appetite
Fatigue (extreme tiredness)
Weight loss
Slower growth or later puberty than expected

Less Common & Extra-intestinal Symptoms

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UC can sometimes show up outside the gut, too These symptoms are less common, but worth knowing about so you can flag them to your team.

👄 Mouth

Mouth sores

🧴 Skin

Skin rashes (e.g., erythema nodosum, psoriasis)

👁️ Eyes

Eye diseases (e.g., uveitis)

Flare-Ups

In UC, periods of symptoms and periods of remission (= no symptoms) alternate. With the right treatment, remission can ideally last not just for several months, but for years.

🔍 Cause of flare-ups

The exact cause of flare-ups is unknown, but potential triggers include gastrointestinal infections and stress. Certain foods can also trigger flare-ups, but these foods vary from person to person. A useful approach might be keeping a food journal to identify foods that seem to trigger or worsen your UC symptoms.

🌡️ Flare-up symptoms

During a flare-up, you are likely to experience some of the symptoms mentioned above, like bloody diarrhea, abdominal pain, and urgency. However, keep in mind that extra-intestinal symptoms can also appear. If you notice any new skin issues, joint pain (arthritis), or eye problems, consult your medical team to determine if these are part of the flare-up and to get appropriate treatment.

When to Seek Help

When experiencing abdominal pain and/or diarrhea, you might wonder if it’s necessary to schedule an appointment with your medical team. Whether or not it warrants a visit can depend on whether you have already been diagnosed with UC.

Before diagnosis

🩺 Talk to your doctor if you have…

any blood in your stool — don’t wait, even if it’s just once
diarrhea that doesn’t go away after a few days
needing to go to the bathroom much more often than usual
abdominal pain that keeps coming back
feeling an urgent need to go that you can’t ignore

These signs don’t necessarily mean you have UC, but your doctor should rule out UC, along with other causes (e.g., other inflammatory bowel diseases, irritable bowel syndrome, or gastrointestinal infections).

After diagnosis

🌡️ Signs that may mean a flare-up

a change in your stools (diarrhea or softer/unformed)
blood in your stool (red, dark red, or black)
abdominal pain or cramping that is worse than usual
more urgency than usual
new symptoms like skin rashes, joint pain, mouth sores, or eye problems

Don’t wait if things feel off — addressing a flare-up early can help you get back to remission faster.

📞

When you reach out, include…

a description of your symptoms
since when you’ve had them
ask about any changes to your treatment or medications
ask for any other instructions for managing the flare-up

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If any symptom is worrying you, contact your medical team. TeenHealthInsight is a health education resource — not a substitute for medical advice, diagnosis, or treatment from your doctor or gastroenterologist.