UC Flare Action Plan: What to Do in the First 24–72 Hours
Last Updated Jan 15, 2026
A ulcerative colitis (UC) flare is a return or worsening of symptoms after a calmer stretch. Common flare signs include urgent, loose bowel movements, blood in the stool, belly cramping or pain, fatigue, and sometimes fever. [1] When symptoms start to change, having a simple 24–72 hour action plan can reduce stress and help the care team act faster. The steps below are general education, not medical advice, and a clinician’s instructions should always come first.
First 24 hours: focus on safety, tracking, hydration, and “easy” food
In the first day, the goal is to quickly understand what is happening and protect the basics, especially fluids and sleep. A short written log can be very helpful later when contacting the gastroenterology (GI) office.
UC flare checklist (quick tracking log):
- Number of bowel movements in 24 hours (and whether urgency is worsening)
- Blood or mucus (none, small streaks, more than usual)
- Belly pain or cramping (mild, moderate, severe)
- Fever or chills
- Nausea or vomiting
- Signs of dehydration (dark urine, dizziness, very dry mouth)
- Medications taken (including any missed doses)
Medication routines matter during this window. Missing doses can contribute to worsening symptoms, and many inflammatory bowel disease (IBD) education resources also caution that non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen may trigger or worsen symptoms, so it helps to check with a clinician or pharmacist before using them for pain. [2]
Food can be simplified without aiming for a “perfect” diet. Many centers suggest a short-term, lower-residue approach after flares, starting with well-tolerated liquids and softer foods, then gradually adding more variety as symptoms settle. [3]
Next 24–72 hours: contact the GI team early, ask about rectal options, and know what counts as urgent
If symptoms are not settling, or if they are escalating, contacting the GI team early is often worth it, even if the visit ends up being reassurance. When calling, sharing the checklist above can help the team judge severity and decide what to do next. In many cases, clinicians may order bloodwork and stool testing to evaluate inflammation and rule out other causes (such as infection). [4]
For flares that involve the rectum or left side of the colon, it may also be appropriate to ask about rectal medications. Clinical guidelines recommend rectal 5-aminosalicylate (5-ASA) therapy for mildly to moderately active ulcerative proctitis, and also discuss topical steroid options for proctitis or left-sided colitis in certain situations. [5] These treatments work locally and are often used alongside oral medicines, but the right choice depends on the individual plan.
Urgent signs (same-day care or emergency evaluation may be needed):
- Severe weakness, dizziness, or very dark urine, which can signal dehydration
- Severe belly or rectal pain
- Bloody stools with worsening symptoms
- Fever over 102°F (39°C) [6]
When symptoms feel “different than usual,” escalate quickly, or include dehydration or high fever, it is reasonable to treat the situation as urgent and use local emergency services when needed.