Diverticulitis is one of the most common gastrointestinal conditions in Western countries, driving more than 2.7 million outpatient visits and 200,000 hospital admissions each year in the United States alone. Among people who develop the small pouches in their colon wall known as diverticulosis, roughly 4 to 15% will go on to experience diverticulitis, the painful inflammation or infection of those pouches.
Overall Prevalence by Region
The underlying condition, diverticulosis, affects 5 to 45% of people in Western countries, with the wide range depending on age and how the diagnosis is made. In East Asian countries, prevalence is lower, between 13 and 25%. Geography also shapes where the problem shows up in the colon. In Western populations, diverticulitis is overwhelmingly left-sided, with right-sided disease appearing in only about 1.5% of cases. In Asian populations, right-sided diverticulitis is far more common, a pattern likely tied to both genetics and dietary differences.
How Age Changes Your Risk
Age is the single strongest predictor. A long-running study in Olmsted County, Minnesota tracked diverticulitis incidence across age groups and found a dramatic curve. Among adults aged 18 to 29, only about 10 per 100,000 people developed diverticulitis in a given year. By ages 50 to 59, that number jumped to 214 per 100,000. It peaked at 535 per 100,000 among people in their 80s.
Put differently, the older you are, the more likely you are to both develop the pouches and to have one become inflamed. When complicated cases (those involving an abscess or perforation) were examined separately, 63% of patients were 60 or older, 31% were between 40 and 59, and just 7% were younger than 40.
A Sharp Rise in Younger Adults
Despite being historically rare in younger people, diverticulitis is becoming significantly more common in adults under 50. Between 1998 and 2005, hospital admissions for diverticulitis rose 26% overall, but for patients under 45 the increase was more than 70%. Previously, young adults accounted for just 2 to 7% of diverticulitis admissions. That figure has climbed to between 18 and 34% in more recent data, nearly a fivefold increase. The reasons aren’t fully understood, but rising obesity rates, more sedentary lifestyles, and dietary changes are the leading suspects.
Differences Between Men and Women
Men are more likely to develop diverticulosis than women at every age until about 80, when the gap disappears entirely. The difference is most pronounced in middle age. Women in their 40s have about 29% lower odds of diverticulosis compared to men the same age. That gap narrows gradually: women in their 50s have roughly 21% lower odds, women in their 60s about 19% lower, and women in their 70s about 9% lower. By age 80, there is no measurable difference between the sexes.
Weight and Lifestyle as Risk Factors
Carrying excess weight meaningfully increases the likelihood of diverticulitis. A large study of women found that those with a BMI of 35 or higher had a 42% greater risk of developing diverticulitis compared to women with a BMI under 22.5. Waist circumference and waist-to-hip ratio told a similar story, with women in the highest category facing about 35 to 40% higher risk. Weight gain over time mattered too: women who gained 20 kilograms (roughly 44 pounds) or more since age 18 had a 73% increased risk compared to women who maintained their weight.
These findings point to abdominal fat specifically as a driver, likely because it promotes chronic low-grade inflammation in the gut wall. Low fiber intake and physical inactivity have also been consistently linked to higher rates of diverticular disease, though the relationship with fiber is more nuanced than older guidelines suggested.
What Happens After a First Episode
One of the most practical questions people have is whether diverticulitis comes back. The answer, based on a decade of follow-up data, is that it does for a substantial number of people. Nearly half of patients (48.6%) experienced at least one recurrence within 10 years of their first uncomplicated episode. Among those who did have a recurrence, about 78% had one to three additional episodes, while roughly 22% had four or more flare-ups over the decade.
These numbers are higher than earlier estimates suggested, which typically placed recurrence rates at around 20 to 30%. The longer follow-up period likely captures episodes that shorter studies miss.
How Often It Turns Serious
Most diverticulitis episodes are uncomplicated, meaning the inflammation resolves with rest, dietary changes, or antibiotics without requiring a procedure. But a meaningful minority become complicated. About 15% of patients admitted with acute diverticulitis develop an abscess, the most common complication. Free perforation, where the colon wall tears open, is rarer but serious, occurring in about 1.5% of cases.
Overall, 15 to 20% of all patients admitted for acute diverticulitis (both complicated and uncomplicated) need surgery during that same hospital stay. For those specifically diagnosed with complicated diverticulitis, the surgery rate climbs to around 50%. These numbers reflect hospitalized patients, though. The majority of diverticulitis episodes are managed entirely in outpatient settings and never reach that level of severity.