Not all patients with acute, uncomplicated diverticulitis need antibiotics. This practice is not cutting-edge—it is ready for retirement. Although antibiotics have been considered the cornerstone of the treatment of acute, uncomplicated diverticulitis, this practice was based on anecdotes and plausibility rather than empirical data that antibiotics were necessary. Now that we have quality data, however, it is clear that this practice pattern did not necessarily generate improved patient outcomes.

The idea of withholding antibiotics for uncomplicated diverticulitis in all but a select group of patients has been brewing for years. In fact, this was covered in an ACEP Now article over half a decade ago, shortly after the American Gastroenterological Association published a recommendation that antibiotics not be given routinely in acute, uncomplicated diverticulitis.^1,2 At that time, two randomized trials demonstrated the safety of observation in select patients.^3,4 Now, in 2023, all major professional-society guidelines recommend only selective use of antibiotics in patients with acute uncomplicated diverticulitis rather than all comers.^2,5,6

What is the Evidence for Symptomatic Treatment Without Antibiotics in Select Patients?

There are several randomized and observational studies supporting treatment without antibiotics in select emergency department (ED) patients.^3,7–10 The two largest trials of ED patients are the DIABOLO and DINAMO studies. The DIABOLO open-label randomized trial analyzed 528 ED patients with acute, uncomplicated first-time diverticulitis to either observational treatment or antibiotics (48 hours of intravenous amoxicillin-clavulanic acid followed by 8 days of oral antibiotics). Interestingly, 8 percent of patients in this study had diverticulitis with a pericolonic abscess of less than five cm. The median time to recovery was 14 days without antibiotics and 12 days with antibiotics and met the criteria for non-inferiority. On long-term follow-up (two years), outcomes remained similar between groups. Recurrent diverticulitis occurred in a nearly identical number of patients (no antibiotics, 15.4 percent versus antibiotics 14.9 percent,) and fewer than 5 percent in each arm had complicated diverticulitis.⁹

Most recently, the DINAMO study randomized 488 ED patients, aged 18–80 years, with acute uncomplicated diverticulitis without significant comorbidities to no antibiotics and symptomatic treatment or amoxicillin-clavulanic acid and symptomatic treatment. The primary outcome, hospitalization, met non-inferiority criteria, as 3.3 percent in the no-antibiotic arm were hospitalized compared with 5.8 percent in the antibiotic arm (difference 2.58 percent [95 percent CI, 6.32 to -1.17 percent]). There were no significant differences between groups in ED revisits (no antibiotics 6.7 percent versus antibiotics 7 percent) or pain at follow-up on days 2, 7, 30, and 90. Interestingly, fewer than half of the patients in the no antibiotic group who returned to the ED were subsequently prescribed antibiotics.⁸