Here, we show that benproperine phosphate (BPP), a cough suppressant, triggers AMPK/mTOR‐mediated autophagy initiation and disturbs Ras‐related protein Rab‐11A (RAB11A)‐mediated autophagosome–lysosome fusion, resulting in excessive accumulation of autophagosomes in pancreatic cancer (PC) cells. The gene discussed is RAB11A; the disease is pancreatic neoplasm.