Ischaemic colitis (IC) is the most frequent form of ischaemia of the digestive tract. Due to the worldwide increasing use of medications, there is a growing interest in drug-induced IC. This study reports a rare case of IC directly due to amoxicillin-clavulanate intake. The objective of the study was to describe the evolution of this novel manifestation. An 18-year-old man, non-smoker, with an insignificant medical history, presented with diarrhoea and cramping abdominal pain that started the day following the end of a 10-day amoxicillin-clavulanate course for recent upper respiratory tract infection. Stool cultures including Clostridium difficile toxin testing were negative. Colonoscopy documented an erosive-ulcerative colitis of the sigmoid and the descending colon. Histological examination of the colon biopsies revealed an IC with focal pseudomembranous areas in the descending-sigmoid colon. Thrombophilia screening tests were negative. The patient was discharged from the hospital without symptoms, and another colonoscopy was performed 3 weeks after the previous one, which documented normal endoscopic and histological findings. Amoxicillin-clavulanate IC is a very rare condition and should be suspected once infectious diseases, vascular/haemodynamic causes and a prothrombotic/hypercoagulable state have been excluded. Immediate discontinuation of the antibiotic leads to rapid disease remission.