Sedatives used during a colonoscopy are midazolam combined with propofol and fentanyl or pethidine, as of 2015, states the National Center for Biotechnology Information. Sedoanalgesia, the sedation type used most often, is performed by a gastroenterologist, an anesthesiologist or a trained nurse. Anesthesiologists administer general anesthesia if it is used.
Sedation and pain medication administered for a colonoscopy help the patient to relax and feel comfortable during the procedure, according to WebMD. During a colonoscopy, the physician inserts a long, lighted tube called a colonoscope into the patient's rectum and colon. The tube enables the physician to examine the interior of the large intestine from the rectum to the lower tip of the small intestine. The physician looks for early signs of cancer, bleeding, polyps or other abnormal conditions. The physician is able to correct some conditions and take tissue samples by inserting instruments through the tube.