Non-antibiotic Management in Acute Uncomplicated Diverticulitis

Diverticulitis is a common condition that causes swelling and pain in part of the colon (the large intestine). Doctors classify it as "mild" when there are no serious complications. For many years, doctors in the United States have treated mild diverticulitis with antibiotics. New studies from Europe suggest that many people with mild diverticulitis may not need antibiotics and can get better with just pain medicines. But this approach has not been tested in the United States, where antibiotics are still the standard treatment. The goal of this clinical trial is to find out if people with mild diverticulitis can be safely treated at home without antibiotics. The main questions it aims to answer are: * Are people treated without antibiotics admitted to the hospital more often than people treated with antibiotics? * Do people treated without antibiotics have more emergency room visits, worsening of their disease, or need for surgery? Researchers will compare two groups of people who come to the emergency department with mild diverticulitis to see if treatment without antibiotics is as safe as treatment with antibiotics. Participants will: * Be sent home with pain medicines (ibuprofen and acetaminophen) only, or with pain medicines plus an antibiotic taken by mouth for 7 days * Follow a liquid diet and slowly return to normal food as they feel better * Come back to clinic for a check-up at 1 to 2 weeks * Answer phone calls about their health at 4 weeks, 3 months, and 6 months

Inclusion Criteria: * Left-sided diverticulitis, primary or recurrent * Signs of diverticulitis on CT-confirmed Hinchey (0 or 1a based on CT final report) * White Blood Cell (WBC) count \