What Causes Ulcerative Colitis (UC) Flare-Ups? Common Mistakes That Make UC Worse

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On June 28, 2025

1. You’re Skipping Your UC Medications

The most important thing to do if you have UC? “Take your medications as prescribed, and work closely with your doctor to stay well,” says Richard Bloomfeld, MD, a gastroenterologist and professor at Wake Forest Baptist Medical Center in Winston-Salem, North Carolina.

A variety of medications can treat UC, depending on the severity of your condition and your overall health. A review tracking refills suggested that many people may not stick to their doctor’s recommendations for some prescription inflammatory bowel disease (IBD) medications. This can contribute significantly to flares and reduced quality of life in people with IBD.

While it may be tempting to skip doses once you feel better, doing so can cause your symptoms to reappear. Skipping medications is the biggest reason that people experience flares, says Laura Yun, MD, a gastroenterologist and assistant professor of medicine at the Feinberg School of Medicine at Northwestern University in Chicago. Whether your doctor has you taking an anti-inflammatory drug, an immunosuppressant, or a combination of medications, none of them will work if you don’t take them as your doctor prescribes.

2. You’re Ignoring How Stressed You Really Are

People with UC often report experiencing stress before a flare. A study involving 110 people with UC found that those with high stress levels were 3.6 times more likely to experience flares than those with low stress levels.

Stress can fire up your sympathetic nervous system, the part of your nervous system linked to your fight-or-flight response, which then releases adrenaline and noradrenaline. These hormones may increase inflammation throughout your body, including the gut, worsening the symptoms of UC.

Stress and IBD have a complex two-way relationship: Stress can trigger and worsen IBD like UC, while IBD symptoms can also worsen stress. At Dr. Yun’s clinic, a psychologist teaches relaxation exercises to people with UC. Relaxation techniques such as meditation and yoga may help you manage stress.

3. You’re Not Avoiding Trigger Foods

“There’s no food or food group that causes or cures ulcerative colitis,” Yun says. But many people with UC say that certain foods either bring on symptoms or make them worse.

During a flare, your doctor may recommend adjustments to your diet. This can mean avoiding foods that trigger symptoms. For example, dairy products can be particularly irritating for people who have both UC and lactose intolerance. You may need to pick dairy alternatives or lactose-free dairy items and pay closer attention to ingredient lists.

Trigger foods differ for everyone who has UC. Aside from dairy, these trigger foods are common:

Sunflower seeds, apple skins, raw kale, and other foods high in insoluble fiber (fiber that doesn’t dissolve in water and is difficult to digest)
Some high-fiber vegetables, such as Brussels sprouts, cabbage, asparagus, and cauliflower
High-fat foods
Foods and drinks with lots of added sugar, like cookies, pastries, sugar-sweetened beverages, and syrup
Artificial sweeteners and sugar alcohols
Spicy foods
Caffeinated beverages

If you’re trying to pinpoint your dietary triggers so that you can limit or avoid them, keep a food diary, and always work with a healthcare practitioner to ensure that you’re getting all the nutrients you need.

4. You’re Avoiding Certain Healthy Foods

It can be hard to eat a healthy diet — or anything at all — if you’re experiencing abdominal pain, cramps, or nausea. But if you’re not eating the right foods, you could be at risk of nutrient deficiencies, malnutrition, and unwanted weight loss.

Because people with UC can lose their appetite, keeping a long-term focus on eating a healthy, balanced diet is crucial.

While no single meal plan works for everyone, many people find they can tolerate the following foods:

Low-fiber fruits such as bananas and raspberries, as well as blended fruits
Fatty fish like tuna, salmon, and mackerel
Cooked veggies like carrots and green beans
Cooked starches like potatoes and sweet potatoes
Cooked and cooled grains such as oatmeal and rice

Cutting leafy greens into small pieces or blending them into a smoothie can help you get your fill of their many health benefits without uncomfortable symptoms.

If you’re struggling to find foods that don’t trigger your symptoms, a doctor or dietitian who specializes in IBD can help you develop a personalized meal plan.

5. You’re Not Drinking Enough Fluids

If you’re experiencing sudden, severe bouts of diarrhea, you risk dehydration as your body loses more fluids than it takes in.

This can be harmful to your overall well-being and interfere with your body’s ability to heal.

Drink as much water as you can during a UC flare. Just keep in mind that you should think twice about some liquids if you have a flare, including sports drinks and sweetened beverages.

Also try to avoid sugary drinks and drinks with sugar substitutes.

6. But You Do Drink Caffeine or Alcohol

Coffee, tea, and soda can make UC flare-ups worse, says Yun, because caffeine is a stimulant that can get your intestines moving — not what you need when you have diarrhea. The same goes for beer, wine, and liquor, which can increase inflammation throughout the body and your risk of flares, and make symptoms worse.

If you have active UC symptoms, consider skipping alcoholic beverages and try to reduce or eliminate caffeinated drinks like tea, coffee, and energy drinks.

7. You’re Drinking Carbonated Beverages

When you’re experiencing a UC flare, sodas and other carbonated drinks can make you uncomfortably gassy.

Because many of these drinks contain caffeine and sugar, both of which can contribute to diarrhea, you might be giving yourself a triple dose of irritation.

Plain water may be your safest bet during a flare.

8. You’re Eating Large Meals

When UC symptoms are active, you can ease your body’s burden by eating frequent, smaller meals so the volume of food and fluid is stable and limited. Consider having five or six small meals every three to four hours instead of three large meals a day.

On top of reducing discomfort from UC symptoms,

this strategy helps maintain a healthy food intake despite the nausea or loss of appetite that might accompany flares.

9. Non-IBD Medications Are Triggering Flares

Taking certain antibiotics could increase the risk of UC flares, according to research.

(Keep in mind that your doctor may put you on an antibiotic to prevent or treat an infection, even if it is unrelated to UC.)

Let your doctor know if you experience diarrhea after starting antibiotics, since a switch in the type of drug may be needed.

Nonsteroidal anti-inflammatory drugs like aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve) can also trigger a UC flare. You should only take these medications if your doctor tells you to, since they can make some UC symptoms worse or trigger a flare.

10. You’re Not on the Right Treatment Plan

Your UC care team will work with you to develop a treatment plan that factors in the severity of your symptoms and your response to medications.

Usually, you’ll start with the least aggressive treatment and move on to stronger medications if necessary. However, some newer approaches to UC therapy start with an aggressive treatment before putting in place a less intensive maintenance plan.

A gastroenterologist with specific training around IBD will help you tailor your treatment plan, based on these factors:

What symptoms you have
Which complications you have
Your overall health

If symptoms get worse or you start to experience more flares, you might need to adjust your current medication regimen. If you aren’t satisfied with the level of control you have over your UC, talk to your doctor about other options.