All patients seen in the emergency department with clinical signs of acute diverticulitis (left iliac fossa abdominal pain, peritoneal irritation signs and/or leucocytosis) will undergo an abdominal computed tomography to confirm the diagnosis and grade the disease according to severity using the modified Neff (mNeff) classification. Those with mild acute diverticulitis (grade 0), following the inclusion criteria and giving informed consent, will be included in the study protocol and will be randomly assigned to one of the treatment arms: symptomatic treatment with NSAID plus antibiotic vs symptomatic treatment with NSAID only. They will be followed-up at 48 hours, 7 days, 30 days and 3 months from the onset of the episode.