Disseminated herpes zoster can present with a wide range of clinical manifestations, including visceral involvement. This case report describes an 89-year-old male who presented with severe abdominal pain, initially without any cutaneous lesions, leading to diagnostic challenges. The patient had acute-onset right lower abdominal pain that was persistent and worsened with movement. Initial diagnostic imaging revealed mild peritoneal edema over the ascending colon without evidence of bowel obstruction, vascular abnormalities, or free air. Due to the severity of the pain, symptomatic treatment was administered. Subsequently, a vesicular rash appeared on the right flank, corresponding to the pain site. This led to the diagnosis of disseminated herpes zoster with peritonitis. Antiviral therapy with intravenous acyclovir was initiated promptly, resulting in clinical improvement. However, postherpetic neuralgia (PHN) developed and required ongoing pain management. This case underscores the importance of including disseminated herpes zoster in the differential diagnosis of acute abdominal pain, particularly in elderly and immunocompromised patients. The absence of an initial rash can delay diagnosis, increasing the risk of complications. Early recognition and antiviral therapy prevent disease progression and improve patient outcomes. Moreover, PHN remains a significant concern, emphasizing the need for effective pain management and preventive strategies, including vaccination. Raising awareness among healthcare providers about atypical presentations of herpes zoster can facilitate early diagnosis and timely intervention, ultimately enhancing patient care.