Chapter 04 · The Basics

Symptoms & Flare-Ups

Crohn’s symptoms can look different for every person, and your symptoms might shift over time. Some start mild and slowly, others start more suddenly. Knowing what’s typical — and what deserves a call to your doctor — helps you feel more in control of your body.

Crohn’s disease symptoms can be non-specific and mild at first or start suddenly and strongly. Some people experience symptoms for over a year before diagnosis. Symptoms may vary depending on the location of the inflammation, and can differ from patient to patient. They alternate with periods of remission (no symptoms) — either period may last for months or years.

General Symptoms

🚽 Gut & bathroom

Abdominal pain (often in the lower abdomen)
Diarrhea or loose stools, sometimes bloody
Nausea and vomiting
Soreness, tears, or skin irritation around the anus (perianal area)

💪 Body & energy

Weight loss due to malabsorption (inflammation reduces nutrient absorption)
Slower growth than expected (which often catches up once Crohn’s is treated)
Anemia (due to ongoing inflammation or blood loss)

👄 Mouth

Mouth redness, swelling, or ulcers

Extraintestinal Symptoms

✨

Crohn’s 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.

🦴 Joints & bones

Arthritis
Osteoporosis

🧴 Skin

Erythema nodosum (tender red or purple bumps, usually on the shins)
Pyoderma gangrenosum (skin ulcers, often on the legs)

👁️ Eyes

Episcleritis (redness and irritation of the white part of the eye)
Uveitis (inflammation inside the eye that can cause pain and blurry vision)

🌡️ Whole body

Fever
Fatigue
Restless leg syndrome

🩺 Liver & kidneys

Liver function issues (e.g., inflammation of the liver or bile ducts, primary sclerosing cholangitis)
Kidney stones

Possible Complications and Health Issues

💛

These are possible — not expected Most complications are rare in teens. Regular care with your medical team helps prevent them, and today’s treatments can manage most of them well.

Some teens may run into complications, but most don’t. The most common ones are strictures (narrowed sections of bowel) and fistulas (small abnormal channels between parts of the bowel or to nearby tissues). Other complications are rare and depend on where Crohn’s is most active. Your medical team watches for these as part of regular care, which is why check-ups matter — they help catch and manage issues early.

🧠

Mental health matters too Living with any chronic disease can feel heavy sometimes — anxiety and low mood are common, and they’re treatable. If you notice it, tell your team. Support is part of your care, not separate from it.

If things feel really heavy or you’re in crisis, please reach out — you don’t have to wait until it’s ‘bad enough.’ Visit findahelpline.com to find a free, confidential helpline in your country.

Flare-Ups

Flare-up symptoms often include typical Crohn’s disease symptoms. However, flare-ups can also present in different symptoms, including extraintestinal symptoms like joint pain, rashes, and fever.

While many symptoms may indicate a flare-up, a single day of stomach pain or diarrhea doesn’t always mean a flare-up. Ongoing or new symptoms that last for several days should be evaluated by your doctor.

🔍 What can trigger a flare-up?

The exact cause of Crohn’s flare-ups is unknown, but several factors may trigger them. Common triggers include:

Specific foods (which vary by person)
Smoking
Stress
Other diseases
Certain medications (e.g., antibiotics, NSAIDs)
Regular gaps in taking medication

⏱️ How long do flare-ups last?

Flare-ups vary in length, but they’re usually not something you’ll be stuck in for months. Today’s medications give your medical team good options to bring a flare under control.

Tip: Keeping a food & symptom journal can help you and your team spot what triggers your flares.

When to Seek Help

Before diagnosis

🩺 Not yet diagnosed?

Loose or runny stools going on for more than 2 weeks
Stomach cramps or pain, often in the middle or lower belly
Blood when you go to the toilet
Feeling sick to your stomach or vomiting
Unintentional weight loss, on-and-off fever, or lots of tiredness
Mouth sores, redness or swelling in your mouth, or soreness around the anus (perianal area)
Symptoms that feel unrelated — like joint pain, skin rashes, or eye pain or redness

After diagnosis

📋 Already diagnosed?

More loose or runny stools than usual, several days in a row
Stomach pain that is new, worse than usual, or hanging around for a week or more
Blood when you go to the toilet recently
New or unusual symptoms — joint pain, swollen joints, blurry or sore eyes, skin rashes, or mouth sores

Urgent care

🚨 Seek care right away

Severe pain with high fever
Feeling very dizzy or dehydrated
Trouble keeping fluids down (nausea/vomiting)
Rectal bleeding or vomiting blood
Fast heartbeat with belly pain and fever

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TeenHealthInsight is a health education website — not a substitute for medical advice. Any symptom that worries you should be brought to your doctor or gastroenterologist. Trust your gut (literally) — if something feels off, reach out to your medical team.