Diverticulitis Flare-Ups

Symptoms and how to get relief

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A diverticulitis flare-up occurs when the pouches in your colon wall (diverticula) become inflamed or infected.

This can cause symptoms such as abdominal pain (often on the lower left side), fever, cramping, diarrhea, or constipation. In severe cases, rectal bleeding may occur.

This article discusses what might cause a diverticulitis flare-up (sometimes called a diverticulitis attack), how to know you are having one, and how a flare-up is diagnosed and treated.

An illustration with symptoms of a diverticulitis flare-up

Illustration by Tara Anand for Verywell Health

Symptoms of a Diverticulitis Flare-Up

Some of the signs and symptoms of a diverticulitis flare-up include:

  • Abdominal pain, aches, or cramps, typically on the lower-left side
  • Abdominal tenderness
  • Bleeding from the rectum
  • Constipation
  • Diarrhea
  • Fever
  • Nausea
  • Pain or burning during urination (sometimes)
  • Vomiting

Flare-up symptoms typically resolve within a few days once treatment is started. Approximately 20% of people who experience one flare-up will have another one.

What Causes Diverticulitis Flare-Ups?

It's not known exactly what causes or triggers a diverticulitis flare-up, but risk factors may include:

  • Having had an episode of diverticulitis in the past
  • Eating red meat regularly
  • Not including enough fiber in the diet
  • Smoking
  • Being overweight
  • Aging

The risk of an acute flare-up of diverticulitis is considered to be under 5%. In the United States, around 200,000 people are hospitalized for diverticulitis each year.

How Diverticulitis Is Diagnosed

If you already know you have diverticulosis, diverticulitis might be suspected right away if you have symptoms of a flare-up. Still, it’s important to know what is causing the symptoms so they can be treated and complications prevented.

The first step in the diagnosis of a diverticulitis flare-up involves your healthcare provider asking questions about your medical history and symptoms. For example, you will be asked questions such as:

  • How bad is the pain?
  • Where is the pain located?
  • Are you experiencing any bleeding?
  • Are you experiencing constipation or diarrhea?

Based on a review of your symptoms, your provider may recommend some of the following tests:

  • Blood tests: A blood test might show if there are more white blood cells than there should be, which could mean an infection.
  • Computed tomography (CT) scan: This is a type of X-ray that’s used to see the organs in the abdomen in cross-section, including the large intestine. 
  • Magnetic resonance imaging (MRI): An MRI uses a strong magnet to create images of the abdominal organs.
  • Stool tests: Diverticulitis won’t be diagnosed with just a stool test, but stool will be tested for infection or other conditions that can cause symptoms.
  • Ultrasound: An ultrasound is a type of test that uses sound waves to make an image of the organs inside the abdomen. 

Ruling Out Other Possibilities

Some of the symptoms of a diverticulitis flare-up can overlap with other diseases. Therefore, it is important to rule out other possible causes.

Some of the conditions that might also be considered when diagnosing diverticulitis are:

What to Do When Diverticulitis Flares Up

A diverticulitis flare-up can often be treated at home.

For very mild symptoms of pain, diarrhea, or nausea, a clear liquid diet is often the first step. This should only be done on the advice of a healthcare provider because a liquid diet doesn’t provide enough calories or nutrients for most people on a long-term basis.

If symptoms improve, more foods will slowly be added back into the diet.

Abdominal pain can be treated with Tylenol (acetaminophen). It is thought that aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), such as Advil (ibuprofen) and Aleve (naproxen), may increase the risk of a future flare-up.

A heating pad may also be used to soothe abdominal pain.

For more serious symptoms, a healthcare professional may prescribe antibiotics to clear up or prevent any infection.

Medical Intervention

If the diverticulitis flare-up can’t be managed at home, hospitalization might be needed. You may need intravenous fluids and antibiotics, as well as pain medication or other treatments.

In rare cases, surgery may be necessary if serious complications develop. This could mean removing the part of the bowel with the inflamed diverticula. It could also mean creating an ostomy so stool is diverted away from the affected part of the bowel.


It may or may not be possible to prevent diverticulitis, but these lifestyle measures may help:

While it was once thought that nuts, popcorn, or seeds could increase the risk of a diverticulitis flare-up, that has been disproven.


Diverticular disease is common and doesn’t usually cause any symptoms. When diverticula become inflamed, however, they can cause symptoms such as abdominal pain, fever, or diarrhea. This is called a diverticulitis flare-up.

Diet changes may be enough to manage the flare. In some cases, hospitalization or surgery may be needed.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Amber J. Tresca
Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16.