By age 60, more than half of Americans have diverticulosis — small pouches that form in the walls of the colon. Most never cause problems. But when one or more of those pouches becomes inflamed or infected, the result is diverticulitis, a condition that sends over 200,000 people to the hospital each year in the United States. Diverticulitis can range from a mild, manageable flare to a serious emergency requiring surgery. Knowing the difference — and understanding your treatment options — matters. For an overview of how digestive conditions connect to broader health, visit our medical conditions guide.
Diverticulosis vs. Diverticulitis: Understanding the Difference
Diverticulosis refers simply to the presence of diverticula — small, bulging pouches that push outward through weak spots in the colon wall, most commonly in the sigmoid colon (the S-shaped section just above the rectum). According to the NIDDK, diverticulosis is extremely common and is generally considered a normal finding related to aging. Most people with diverticulosis are asymptomatic and will never need treatment.
Diverticulitis occurs when one or more diverticula become inflamed or infected. This happens in an estimated 10 to 25 percent of people with diverticulosis. The inflammation can be uncomplicated (localized inflammation without abscess, perforation, or other structural damage) or complicated (involving abscess formation, perforation, fistula, or bowel obstruction). About 75 percent of diverticulitis cases are uncomplicated.
The umbrella term “diverticular disease” encompasses both diverticulosis and diverticulitis, as well as diverticular bleeding — a separate complication where a blood vessel adjacent to a diverticulum erodes and bleeds, sometimes profusely. Understanding this spectrum helps clarify what your doctor means when discussing your diagnosis.
What Causes Diverticulitis?
The exact mechanism that triggers inflammation in a diverticulum is still debated. The traditional theory held that a piece of food or hardened stool (a fecalith) became trapped in a diverticulum, blocking its narrow opening and creating a micro-environment where bacteria could proliferate. Research published in Gastroenterology suggests the process may be more complex, involving alterations in the colonic microbiome, localized ischemia (reduced blood flow), and changes in colonic motility.
The formation of diverticula themselves is linked to increased pressure within the colon. A low-fiber diet leads to smaller, harder stools that require more forceful muscular contractions to move through the colon. Over time, this elevated intraluminal pressure pushes the inner lining of the colon through weak points in the muscular wall, creating diverticula. This explains why diverticular disease is far more common in Western countries with low-fiber diets compared to regions where high-fiber diets predominate.
Risk factors for developing diverticulitis specifically include aging, obesity (particularly abdominal obesity), physical inactivity, smoking, a diet low in fiber and high in red meat, and regular use of NSAIDs, opioids, or corticosteroids. Genetics also play a role — twin studies suggest that approximately 40 to 50 percent of the susceptibility to diverticular disease is heritable.
Recognizing the Symptoms
The hallmark symptom of diverticulitis is pain in the lower left abdomen. Because most diverticula develop in the sigmoid colon, which is located in the left lower quadrant, this is where inflammation is typically felt. However, in people of Asian descent, right-sided diverticula (and therefore right-sided pain) are more common. The pain is usually constant rather than crampy and may develop gradually or come on suddenly.
According to the Mayo Clinic, other common symptoms include fever, nausea, vomiting, abdominal tenderness, changes in bowel habits (constipation is more common than diarrhea), bloating, and occasionally urinary symptoms if the inflamed colon irritates the bladder. Mild cases may present with only dull, persistent left lower quadrant discomfort and low-grade fever.
When to seek emergency care: Call 911 or go to the nearest emergency room if you experience severe, worsening abdominal pain, high fever (above 102 degrees Fahrenheit), inability to keep fluids down, signs of peritonitis (rigid, board-like abdomen with severe diffuse pain), or rectal bleeding with lightheadedness. These may indicate a perforated diverticulum or other surgical emergency.
How Diverticulitis Is Diagnosed
Diagnosis begins with a clinical assessment — your symptoms, physical examination findings (particularly tenderness in the left lower abdomen), vital signs, and blood work. An elevated white blood cell count and elevated C-reactive protein support the diagnosis but are not specific. The American College of Gastroenterology recommends CT scan of the abdomen and pelvis with intravenous contrast as the diagnostic study of choice. CT imaging has a sensitivity of approximately 94 percent for diverticulitis and can also identify complications such as abscesses, fistulas, and free air indicating perforation.
Ultrasound may be used as an initial test in some settings, particularly in Europe and in patients where radiation exposure is a concern (such as younger adults or pregnant women), though it is more operator-dependent than CT. Colonoscopy is generally avoided during an acute flare due to the risk of perforation but is typically recommended 6 to 8 weeks after recovery to rule out colorectal cancer, particularly in patients over 50 or those who haven’t had a recent screening. For more on screening, see our guide on colorectal cancer.
Importantly, diverticulitis must be distinguished from other conditions that cause similar symptoms, including irritable bowel syndrome, inflammatory bowel disease, colorectal cancer, ovarian pathology in women, and urinary tract infections. The CT scan is instrumental in making this differential diagnosis accurately.
Treatment of Uncomplicated Diverticulitis
Uncomplicated diverticulitis — meaning inflammation without abscess, perforation, fistula, or obstruction — is increasingly managed on an outpatient basis. Recent evidence has shifted treatment paradigms significantly. A landmark study published in the British Journal of Surgery and subsequent trials found that many patients with uncomplicated diverticulitis recover without antibiotics, challenging the long-held assumption that antibiotics were always necessary.
Current guidelines from the American Gastroenterological Association suggest that antibiotics should be used selectively rather than routinely for uncomplicated diverticulitis. Patients who are immunocompromised, have significant comorbidities, show signs of systemic illness, or have more severe imaging findings should still receive antibiotics. When prescribed, a typical regimen includes a combination of metronidazole and a fluoroquinolone (or amoxicillin-clavulanate) for 7 to 10 days.
Supportive care includes a clear liquid diet during the acute phase, gradually advancing to a low-residue diet and then a normal diet as symptoms improve. Over-the-counter pain relievers such as acetaminophen are preferred; NSAIDs should be avoided as they may worsen inflammation. Most patients with uncomplicated diverticulitis improve within 2 to 3 days and recover fully within 1 to 2 weeks.
Managing Complicated Diverticulitis
Complicated diverticulitis requires more aggressive intervention. Diverticular abscesses — pockets of infected fluid near the inflamed colon — are classified using the Hinchey system. Small abscesses (under 3 to 4 centimeters) may resolve with intravenous antibiotics alone. Larger abscesses typically require CT-guided percutaneous drainage, where a radiologist inserts a needle through the skin to drain the infected fluid, combined with antibiotic therapy.
Free perforation — a hole in the colon wall allowing intestinal contents to spill into the abdominal cavity — is a surgical emergency. According to the American College of Surgeons, this typically requires urgent surgery to remove the affected segment of colon. The traditional approach is a Hartmann procedure, where the diseased segment is resected, the rectal stump is closed, and a temporary colostomy is created. In some cases, a primary anastomosis (reconnecting the bowel ends) with or without a diverting ileostomy may be feasible.
Fistulas — abnormal connections between the colon and adjacent organs such as the bladder (colovesical fistula) or vagina (colovaginal fistula) — almost always require surgical repair. Colovesical fistulas present with recurrent urinary tract infections, air in the urine (pneumaturia), or passage of fecal matter in the urine. Bowel obstruction from diverticular strictures may require endoscopic dilation or surgical resection depending on severity and acuity.
When Surgery Is Recommended
Elective surgery for diverticulitis — specifically, sigmoid colectomy (removal of the sigmoid colon) — was previously recommended after two episodes of uncomplicated diverticulitis. This “number-of-episodes” rule has been largely abandoned. Current practice individualizes the surgical decision based on the severity and impact of episodes, the patient’s age, overall health, immune status, and quality of life.
The American Society of Colon and Rectal Surgeons recommends elective surgery for patients with complicated diverticulitis (abscess, fistula, or stricture), immunosuppressed patients who are at higher risk for perforation, and patients whose recurrent episodes significantly impair quality of life. Surgery is not recommended solely based on a count of uncomplicated episodes.
Laparoscopic sigmoid colectomy is the preferred technique, offering less pain, shorter hospital stays (typically 3 to 5 days), and faster recovery compared to open surgery. The diseased sigmoid colon is removed and the remaining colon is reconnected to the upper rectum. A colostomy is rarely needed in the elective setting. Long-term outcomes after elective surgery are excellent, with recurrence rates of less than 5 percent.
Diet and Prevention Strategies
Once you’ve recovered from a diverticulitis episode, dietary and lifestyle modifications can help reduce the risk of recurrence. High-fiber intake is the most consistently supported preventive strategy. The NIDDK recommends aiming for 25 to 35 grams of fiber daily through fruits, vegetables, whole grains, and legumes. Fiber increases stool bulk, reduces colonic transit time, and decreases intraluminal pressure.
A notable update to outdated advice: the longstanding recommendation to avoid nuts, seeds, popcorn, and corn has been disproven. A large prospective study published in the Journal of the American Medical Association found that men who consumed the most nuts and popcorn actually had a lower risk of diverticulitis. There is no evidence that these foods become trapped in diverticula or trigger inflammation.
Regular physical activity — at least 30 minutes of moderate exercise most days — reduces diverticulitis risk by approximately 25 percent based on observational data. Maintaining a healthy weight, not smoking, and limiting red meat consumption are additional evidence-based strategies. Some physicians recommend daily probiotics, though the evidence for this remains mixed. Managing healthcare costs proactively by investing in a fiber-rich diet and regular exercise may reduce the need for expensive emergency interventions down the line.
Frequently Asked Questions
Can diverticulitis go away on its own?
Mild uncomplicated diverticulitis can improve without antibiotics in many patients, with supportive measures like rest, a temporary liquid diet, and acetaminophen for pain. However, you should not attempt to self-diagnose or self-treat abdominal pain. A proper evaluation is needed to confirm the diagnosis and rule out complications that require specific treatment. Even if antibiotics aren’t prescribed, medical monitoring during a flare is important.
Is diverticulitis a lifelong condition?
Diverticulosis — the underlying presence of diverticula — is permanent, as the pouches do not resolve once formed. However, not everyone with diverticulosis will develop diverticulitis. Among those who have one episode of diverticulitis, approximately 20 to 35 percent will have a recurrence. With proper dietary management, lifestyle changes, and in some cases elective surgery, many people are able to prevent further flares and live without significant limitations.
What foods should I avoid with diverticulitis?
During an active flare, your doctor will likely recommend a clear liquid diet (broth, gelatin, water, clear juices) for a day or two, then a low-residue diet as you improve. Once recovered, the goal is the opposite — a high-fiber diet to prevent recurrence. There is no need to avoid nuts, seeds, popcorn, or corn, as the old restriction has been debunked by research. Limiting red meat and processed foods may be beneficial based on observational studies linking Western diets to higher diverticular disease risk.
How do I know if my diverticulitis is serious?
Warning signs of complicated diverticulitis include high fever (above 102 degrees Fahrenheit), severe or worsening abdominal pain despite treatment, inability to tolerate fluids, abdominal rigidity, rectal bleeding, or symptoms of a fistula (air or stool in the urine, vaginal discharge of gas or stool). If you’ve been diagnosed with uncomplicated diverticulitis and your symptoms are not improving within 2 to 3 days of treatment, contact your doctor for reassessment — imaging may need to be repeated.
Can young people get diverticulitis?
Yes. While diverticular disease is most common in people over 50, there has been a notable increase in diverticulitis among adults under 40 in recent decades. Research suggests this trend may be linked to rising obesity rates and dietary changes. Young patients with diverticulitis were once thought to have a more aggressive disease course, but more recent data challenges this assumption. Treatment decisions for younger patients should follow the same individualized approach as for older adults.
Living With Diverticular Disease: What to Do Next
If you’ve been diagnosed with diverticulosis on a routine colonoscopy, there’s no need for alarm — but there is an opportunity to take preventive action. Gradually increase your fiber intake (adding fiber too quickly can cause gas and bloating), stay physically active, maintain a healthy weight, and drink plenty of water to complement the higher fiber in your diet.
If you’ve experienced diverticulitis, work with your doctor to develop a plan for flare management and prevention. Know the warning signs that warrant a call to your physician versus a trip to the emergency room. Ask about scheduling a follow-up colonoscopy if one hasn’t been done recently. Discuss whether elective surgery makes sense in your particular situation, especially if you’ve had complicated disease or frequent recurrences that affect your daily life.
Keep in mind that diverticular disease is manageable for the vast majority of patients. Most people with diverticulosis never develop diverticulitis. Most people who have one episode recover fully with conservative treatment. And even those who require surgery generally achieve excellent long-term outcomes. The condition calls for awareness and proactive management — not fear.