When to Go to the ER for a Crohn’s Flare (Red Flags + What They’ll Check)
Last Updated Jan 15, 2026
A Crohn’s disease flare can feel scary, especially when symptoms change fast. Many flares can be handled through a gastroenterology (GI) team, but some symptoms suggest dehydration, infection, heavy bleeding, or a blockage that needs urgent evaluation. This guide explains common red flags for a Crohn’s flare ER visit, what the emergency room (ER) often checks, and practical ways to communicate needs clearly during a high-stress moment.
Red flags that make a Crohn’s flare an emergency (or close to one)
Some Crohn’s flare emergency symptoms are concerning because they can signal complications, not “just” inflammation. Emergency evaluation is commonly recommended when there is severe abdominal pain, bleeding that does not stop or is heavy, or vomiting that looks like blood or stool (or looks like coffee grounds), since these can point to serious bleeding or other emergencies. [1]
Other red flags are about possible bowel obstruction signs. A blockage can cause cramping abdominal pain and bloating, nausea and vomiting, and in a complete obstruction, not being able to pass gas or stool. [2] These symptoms are especially important if there is a history of strictures (narrowing) or prior obstruction.
Red flags can also come from body-wide stress. Severe dehydration or malnourishment, severe belly pain with a high temperature and fast heartbeat, or nonstop bleeding are examples of situations where urgent hospital care may be needed. [3] Dehydration can happen quickly during diarrhea or vomiting. Moderate dehydration may require intravenous (IV) fluids given in urgent care, the ER, or the hospital. [4]
Fever during a flare deserves extra caution, particularly for people taking immune-suppressing medicines. For example, infliximab (an anti-tumor necrosis factor, or anti-TNF, biologic) can be associated with infections, including serious infections. [5]
What the ER typically checks during a Crohn’s flare, and ways to advocate
In the ER, the first goal is usually stabilization (vital signs, hydration, symptom control) and the second goal is finding the cause (flare vs infection vs complication). Many teams start with blood and stool testing. Common bloodwork includes a complete blood count (to look for anemia or infection), kidney function and electrolytes (important when dehydration is possible), and inflammation markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP). Stool testing may be used to look for infection as a driver of diarrhea. [6]
Imaging is often used when symptoms are severe or when obstruction, perforation, or other complications are a concern. Depending on the situation, the ER may order an abdominal X-ray, a computed tomography (CT) scan (sometimes CT enterography for more small-bowel detail), or magnetic resonance imaging (MRI). [7] These tests can help identify inflammation patterns and urgent complications that may change next steps.
Care teams may also use results from basic testing (blood tests, stool tests, CT scan) to decide whether more specialized evaluation is needed later, such as colonoscopy arranged outside the ER. [8] For self-advocacy, it often helps to share a simple Crohn’s “snapshot”: diagnosis location (small bowel, colon, both), prior surgeries, known strictures, current medicines and last doses, allergies, and recent infections or antibiotics. If symptoms feel dismissed, asking what complications are being ruled out (dehydration, obstruction, infection, bleeding) can refocus the conversation on safety.