What stops a flare depends on how severe it is and what triggered it

A flare-up of ulcerative colitis means your symptoms have gotten worse — more frequent bowel movements, blood in stool, abdominal pain, or urgency. Stopping it usually requires medication, but the specific drug and dose depend on whether you have mild, moderate, or severe inflammation. Your gastroenterologist will examine you, possibly order blood work or imaging, and then prescribe based on what they find. There is no single "flare-stopper" that works for everyone.

The medications that work are the same ones used to prevent flares in the first place — 5-aminosalicylates (5-ASAs), corticosteroids, immunosuppressants, and biologic drugs. During a flare, the dose usually goes up, the frequency increases, or a new medication is added. Some people need hospitalization if the flare is severe enough to cause dehydration, severe bleeding, or signs of toxic megacolon.

Key Takeaways

  • Mild flares often respond to increased doses of 5-ASA medications like mesalamine, which reduce inflammation in the colon lining.
  • Moderate flares typically require a short course of oral corticosteroids (usually prednisone) to suppress the immune response quickly.
  • Severe flares may need IV corticosteroids, biologic medications, or hospitalization if you cannot keep fluids down or are bleeding heavily.
  • Identifying your personal triggers — certain foods, stress, stopping medication, or infections — and avoiding them can prevent flares from starting.
  • Staying on maintenance medication between flares, even when you feel well, is the most effective way to reduce how often flares occur.

How 5-ASA medications work during a flare

5-ASA drugs like mesalamine, sulfasalazine, and balsalazide reduce inflammation by acting directly on the colon lining. During a flare, your doctor may increase the daily dose or switch to a formulation that reaches different parts of the colon. Some versions are tablets, some are enemas or suppositories that deliver the drug locally, and some are granules you sprinkle on food.

These medications work best for mild to moderate flares and take several days to a week to show effect. They are not fast-acting, so if your flare is severe or worsening, your doctor will add or switch to something stronger rather than wait for a 5-ASA to work alone. Once the flare calms, you typically stay on a 5-ASA at a maintenance dose to prevent the next one.

When corticosteroids are needed

Corticosteroids like prednisone suppress the immune system and reduce inflammation quickly — often within days. For a moderate flare, your doctor prescribes oral prednisone at a higher starting dose (often 40 to 60 mg daily) and then tapers it down over two to eight weeks as your symptoms improve. This prevents the side effects that come with long-term steroid use.

Corticosteroids are not meant for long-term maintenance because of risks like bone loss, infection, and weight gain. They are a short-term tool to get a flare under control. If you need steroids repeatedly or cannot taper off them, your doctor will usually add or switch to an immunosuppressant or biologic medication to prevent future flares and let you stop the steroids.

For severe flares, IV corticosteroids (methylprednisolone) are given in a hospital or infusion center because they work faster and bypass the digestive system when your gut is too inflamed to absorb oral medication reliably.

Biologic and immunosuppressant medications for frequent or severe flares

If you have flares that do not respond to 5-ASAs and steroids, or if you have them so often that you cannot taper off steroids, your gastroenterologist will likely prescribe a biologic or immunosuppressant. Biologics like infliximab (Remicade), adalimumab (Humira), vedolizumab (Entyvio), and ustekinumab (Stelara) target specific parts of the immune system that drive inflammation in ulcerative colitis. Immunosuppressants like azathioprine and 6-mercaptopurine work differently but also reduce the immune attack on the colon.

These drugs take weeks to months to reach full effect, so they are started before or during a flare to prevent the next one, not to stop an active flare immediately. Once they are working, many people have far fewer flares or go into remission. They do carry risks — increased infection risk, liver or blood count changes — so your doctor monitors you with blood tests during treatment.

Rest, diet, and hydration during a flare

While medication is doing the work, your job is to stay hydrated and avoid foods that make symptoms worse. During a flare, your colon is inflamed and your bowel movements are frequent, so you lose fluids and electrolytes. Drink water, broths, and electrolyte drinks. Avoid high-fiber foods, dairy (if you are lactose intolerant), caffeine, alcohol, and very hot or very cold foods, which can trigger more bowel movements.

Some people find that a low-residue diet — soft, bland foods that are easy to digest — helps during a flare. Examples include white rice, plain chicken, eggs, white bread, and bananas. Once the flare settles, you can gradually reintroduce other foods and figure out which ones are your personal triggers. Keep a food diary if you are unsure.

Rest matters too. Stress and fatigue can worsen flares, so give yourself permission to slow down. If you work, talk to your employer about adjusting your schedule or working from home if possible during a bad flare.

When to seek urgent care

Most flares can be managed at home with medication adjustments and your gastroenterologist's guidance. But go to the emergency room if you have severe abdominal pain that does not ease with medication, blood in stool that is heavy or does not slow down, signs of dehydration (dizziness, dark urine, extreme thirst), fever above 101.5°F, or more than six to eight bloody stools per day.

These signs can mean your flare is severe enough to need IV fluids, IV medications, or hospitalization. In rare cases, a severe flare can lead to toxic megacolon (dangerous colon swelling) or perforation, which are medical emergencies. Your doctor may also recommend hospitalization if you cannot keep food or fluids down or if you are losing blood faster than your body can replace it.

Preventing the next flare

Once a flare is under control, the goal shifts to preventing another one. This means taking your maintenance medication every day, even when you feel completely well. Many people stop their medication when symptoms disappear, thinking they are cured, but ulcerative colitis is a chronic condition — the inflammation returns without medication. Staying on maintenance therapy cuts flare frequency dramatically.

Identify what triggered this flare if you can. Common triggers include stopping or skipping medication, a bacterial or viral infection, stress, certain foods, or nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. If you know your triggers, you can avoid them or manage them differently next time. Some people benefit from stress-reduction techniques like therapy, meditation, or exercise. Others find that working with a dietitian to identify food triggers helps prevent flares.

Frequently Asked Questions

How long does it take for a flare to stop?

Mild flares may improve in one to two weeks with increased 5-ASA medication. Moderate flares typically take two to four weeks with corticosteroids. Severe flares can take longer and may require hospitalization. Biologic medications take weeks to months to work, so they are started to prevent future flares rather than stop an active one quickly.

Can I stop my maintenance medication if I have not had a flare in months?

No. Maintenance medication prevents flares from happening. Stopping it, even after months or years without symptoms, usually leads to a flare within weeks or months. Talk to your gastroenterologist before making any changes to your medication routine.

What should I eat during a flare?

Stick to bland, low-fiber foods like white rice, plain chicken, eggs, white bread, and bananas. Avoid high-fiber vegetables, whole grains, dairy (if you are lactose intolerant), caffeine, alcohol, and spicy foods. Drink plenty of water and electrolyte drinks to replace fluids lost from frequent bowel movements.

Is surgery ever needed to stop a flare?

Surgery is not used to stop a single flare. It is considered only if you have severe, frequent flares that do not respond to medication, or if complications like toxic megacolon or perforation occur. Surgery removes the colon and rectum, which cures ulcerative colitis because the disease only affects the colon.

Can stress cause a flare?

Stress does not cause ulcerative colitis, but it can trigger or worsen a flare in people who already have the condition. Managing stress through therapy, exercise, meditation, or other techniques may help reduce flare frequency, though medication remains the primary treatment.