Whether or not gallbladder polyps 0.4 cm are dangerous should be determined according to the nature of the polyp, benign polyps are not dangerous, malignant polyps are more dangerous. Benign gallbladder polyps 0.4 cm usually do not cause obvious clinical manifestations, a few patients may experience epigastric pain, nausea and vomiting, etc. A part of benign gallbladder polyps may become cancerous, but the chance of this is relatively low. For patients with 0.4 cm gallbladder polyps that are symptomatic or suspected to be precancerous, laparoscopic cholecystectomy should be performed; for 0.4 cm malignant gallbladder polyps, i.e., gallbladder cancer, prompt treatment is needed after the diagnosis is clear, and the long term survival rate of gallbladder cancer after the treatment is also relatively low. Therefore, this type of polyp is more dangerous. Gallbladder polyps 0.4 cm should go to the hospital in time, improve the examination, clear the nature of the polyp under the guidance of the doctor to choose the appropriate treatment.