Monitoring & follow-up
A ulcerative colitis flare can start with a single alarming trip to the bathroom or a gradual return of symptoms you hoped were behind you. Either way, the question is the same: what do you actually do right now? Generic advice to "rest and stay hydrated" is not wrong, but it skips the part most patients need, which is a structured plan for assessing severity, taking the right immediate actions, and knowing when the situation requires professional intervention. Whether your flare was triggered by stress, a missed dose, or stopping medication, the steps below provide a practical framework for the first 24 hours through resolution, organized by how severe things are.
Assess Your Severity Level in the First Few Hours
Before you can respond effectively to a ulcerative colitis flare up, you need to gauge where you fall on the severity spectrum. Clinicians use the Truelove and Witts criteria to classify flares, and a simplified version can help you make better decisions at home.
A mild flare generally means fewer than four bowel movements per day, small amounts of blood, no fever, and a resting heart rate under 90 beats per minute. A moderate flare involves four to six bowel movements daily with more noticeable bleeding, some abdominal pain, and mild fatigue. A severe flare means six or more bloody bowel movements per day along with at least one systemic sign: fever above 37.8 degrees Celsius (100 degrees Fahrenheit), heart rate over 90, or feeling dizzy and weak.
Start documenting from the very first symptom. Count bowel movements, note the amount of blood, take your temperature, and check your pulse. According to the American College of Gastroenterology's 2025 guidelines, objective documentation of symptom frequency and systemic markers directly influences how quickly your gastroenterologist can make treatment decisions. This data turns a phone call of "I think I'm flaring" into a clinical picture your care team can act on.
Immediate Actions for Mild to Moderate Flares
If your symptoms point to a mild or moderate flare, there are concrete steps to take in the first 24 hours. Contact your gastroenterologist's office and share your symptom data. Many GI practices have triage protocols for flare calls and can adjust your treatment without requiring an in-person visit.
On the medication front, the Mayo Clinic recommends continuing your current maintenance medications unless your doctor advises otherwise. If you have been prescribed a "rescue" course of mesalamine suppositories or rectal steroids for previous flares, ask your GI team whether to restart them. For pain, use acetaminophen only. Avoid NSAIDs like ibuprofen and naproxen, which can worsen colonic inflammation and trigger or prolong flares.
For diet during a flare, shift to low-residue foods: white rice, bananas, cooked carrots, lean poultry, and broth. Avoid raw vegetables, whole grains, and dairy if they typically bother you. The goal is to reduce mechanical irritation in an already inflamed colon. Drink enough fluid to replace what you are losing through diarrhea, and consider an oral rehydration solution if bowel movements are frequent. Ulcerative colitis flare ups at night can be especially disruptive, so keep supplies near the bed: water, wipes, barrier cream for perianal skin, and a change of clothes.
When a Flare Follows Stopping Medication
An ulcerative colitis flare after stopping meds deserves special attention because the path back to remission may look different than a spontaneous flare. WebMD reports that discontinuing UC medication, whether intentionally or because of insurance gaps, carries a high risk of relapse. Worse, some medications, particularly biologics, may not work as well the second time around if your body develops antibodies during the gap in treatment.
If you stopped medication on your own, contact your GI team immediately and be honest about the timeline. They need to know exactly when you stopped, what you were taking, and how quickly symptoms returned. This information helps them decide whether to restart the same therapy or switch to an alternative. If you stopped because of side effects or cost, say so. Your gastroenterologist can often find solutions, including patient assistance programs or therapeutic substitutions, that you may not be aware of. The most important thing is to avoid the cycle of starting and stopping treatment, which makes each subsequent flare harder to control.
When to Go to the Emergency Room
Knowing when to go to the ER for ulcerative colitis can prevent life-threatening complications. Acute severe ulcerative colitis is a medical emergency, and according to guidance published in the World Journal of Gastrointestinal Pharmacology and Therapeutics, any patient with six or more bloody stools per day plus at least one sign of systemic toxicity, including a heart rate above 90, temperature above 37.8 degrees Celsius, or hemoglobin below 10.5 g/dL, should be evaluated in a hospital setting.
Go to the emergency room if you experience any of the following:
Six or more bloody bowel movements in a day, persistent vomiting, or an inability to keep down fluids
Severe abdominal pain with distension, especially if your abdomen feels rigid or tender to touch
Signs of significant dehydration or blood loss, such as dizziness upon standing, dark or absent urine, confusion, or a heart rate that stays above 100 at rest
At the hospital, doctors will likely run blood work, stool studies to rule out infections like C. difficile, and potentially imaging. According to MedicineNet, hospital treatment for acute severe UC typically involves intravenous corticosteroids, with response assessed within three to five days. If IV steroids fail, rescue therapy with infliximab or cyclosporine may follow. Understanding this timeline in advance helps reduce the fear and uncertainty of hospitalization.
How Long a UC Flare Lasts and What Influences Recovery
How long does a UC flare last? The honest answer is that it varies widely. Mild flares with prompt treatment adjustment may resolve within days to a couple of weeks. Moderate flares often take several weeks, particularly if a new medication needs time to reach therapeutic levels. Severe flares requiring hospitalization can take weeks to months before full remission is achieved. HealthCentral notes that the biggest factors influencing flare duration are how quickly treatment starts, how severe the inflammation is, and whether the patient was adherent to maintenance therapy before the flare began.
This is where day-by-day tracking becomes directly useful for recovery. Recording bowel movement frequency, blood volume, pain levels, and dietary intake gives your GI team the information they need to distinguish between a flare that is responding to treatment and one that requires escalation. Rather than relying on memory at a follow-up appointment weeks later, real-time data shortens the feedback loop between you and your care team.
When a flare starts, open Aidy and start tracking immediately. Having day-by-day data helps your GI assess severity and adjust treatment faster.