To relieve perceived pain in patients undergoing colonoscopy, we developed an endoscopist-patient co-participative VR tool (EPC-VR) based on A Neurocognitive Model of Attention to Pain. It allows the patient to play a VR game actively and supports the endoscopist in triggering a distraction mechanism to divert the patient's attention away from the medical procedure. We performed a comparative clinical study with 40 patients. Patients' perception of pain and affective responses were evaluated, and the results support the effectiveness of EPC-VR: active VR playing with endoscopists' participation can help relieve the perceived pain and scare of patients undergoing colonoscopy. Finally, 87.5% of patients opt to use the VR application in the next colonoscopy.