Abstract
BACKGROUND: Colitis is one of the immune-related side effects of immunotherapy. Usually, such type of side effect was reported to develop within a few weeks of treatment initiation, our case started within a few days. CASE SUMMARY: We present a case of a 37-year-old gentleman with bright red loose stools, abdominal pain, and tenesmus. A diagnosis of colitis was made based on endoscopic and histologic findings. Treatment was thereafter continued with oral steroids and discontinuation of the immunotherapy medications. Symptoms resolved after starting the treatment and the patient continued to be symptom-free on subsequent follow-up. The unique about this case report is that the patient developed bloody diarrhea within five days of the 1(st) immunotherapy cycle, and the patient was on combined ipilimumab and nivolumab. CONCLUSION: Immunotherapy related complications might occur within days from being on immunotherapy; we need more research to open the way for future pathological and clinical research to further understand the pathophysiology behind it.