<prompt> A gastric ulcer is said to be refractory when it fails to heal after therapy for:6 weeks8 weeks12 weeks14 weeks  <response>: A gastric ulcer that fails to heal after 12 weeks and a duodenal ulcer does not heal at 8 weeks of therapy should be considered refractory. Cause of refractory ulcers: Malignancy Zollinger Ellison syndrome Cigarette smoking Ischemia Crohns disease Lymphoma Eosinophilic gastroenteritis Infections TB,CMV Ref: Harrisons principles of internal medicine, 18th edition, Page: 2452 