IntroductionIntestinal obstruction is a common complication in patients with advanced malignancies, often attributed to the disease itself or as a side effect of opioid analgesics used for pain management. However, the occurrence of intestinal obstruction following antituberculosis therapy is rare.Case presentationWe report a unique case of a 58-year-old Asian male diagnosed with stage IV pancreatic carcinoma and pulmonary tuberculosis. The patient was initiated on a regimen of ethambutol hydrochloride, pyrazinamide, rifampicin, and isoniazid tablets (II) for tuberculosis, alongside morphine for the management of severe cancer-related pain. Subsequently, he developed symptoms indicative of intestinal obstruction. Despite discontinuation of morphine, the patient’s symptoms persisted until he autonomously ceased all medications, leading to a rapid improvement in his condition. This unexpected resolution highlighted the antituberculosis drugs as the probable cause of his intestinal obstruction.ConclusionsThis case underscores the importance of considering antituberculosis drugs as a potential cause of intestinal obstruction, especially in patients who do not respond to conventional management strategies for drug-induced gastrointestinal side effects. It also emphasizes the need for heightened vigilance and monitoring when prescribing these medications to patients with advanced malignancies, to promptly identify and address rare but significant side effects.