When it comes to surgery, one of the biggest concerns is the pain caused by the surgical trauma to the patient. Some patients may be discouraged from facing minor and medium-sized surgical procedures because of this. In fact, with the development of medicine and pharmacology, pain is no longer a problem, and anesthesiologists can use a variety of analgesic drugs to suppress pain during and after surgery, allowing patients to pass the perioperative period safely and comfortably. Today, we will introduce you to several commonly used narcotic analgesics. Dulcolax: This drug has a long history, and its scientific name is pethidine, which has been used for anesthesia and postoperative analgesia. The dose for adults is usually 50 to 100 mg/dose (i.e., half to 1 dose/dose). Dulcolax has obvious side effects, mainly nausea and vomiting and respiratory depression, which may cause death if complications such as apnea are not detected and treated in time. This drug has been largely withdrawn from clinical practice because of the availability of new drugs. Morphine: This drug is also a familiar analgesic to the general public and has been used in clinical practice for many years, but in recent years it has been withdrawn gradually with the use of new drugs. The analgesic strength of morphine is 10 times that of dulcolax. Morphine produces analgesia by binding to a variety of opioid receptors distributed in the brain and spinal cord, and it is currently used mainly for postoperative analgesic treatment. The main side effects of morphine are nausea and vomiting, respiratory depression, itching of the skin, urinary retention and constipation. Since morphine causes an increase in intracranial pressure, it is not suitable for use in patients with traumatic brain injury. Fentanyl: This is actually a family of synthetic narcotic analgesics, of which fentanyl is the patriarch. The analgesic strength of fentanyl is 100 times greater than that of morphine. It is currently one of the most commonly used narcotic analgesics in the perioperative period, and its side effects include nausea and vomiting, stiffness of the chest wall muscles after administration, and respiratory depression. Because of the drug’s mild effect on blood pressure, heart rate and other circulatory indicators, cardiovascular surgery anesthesia is mainly based on high-dose fentanyl anesthesia. Sufentanil: This drug is also a member of the fentanyl family, and its analgesic intensity is 10 times that of fentanyl. The controllability of sufentanil is better than that of fentanyl, therefore, sufentanil continuous infusion has replaced fentanyl split dosing gradually promoted in cardiovascular surgery anesthesia. Rifentanil: Rifentanil is the strongest analgesic drug in the fentanyl family, and its analgesic strength is 30 times that of fentanyl. The most important feature of remifentanil is that it has a short half-life and is metabolized by specific esterases in the body, and it expires in just a few minutes after stopping the drug. Because of this, postoperative analgesia must be used when using remifentanil anesthesia, otherwise the patient will feel unbearable pain soon after waking up from anesthesia. The strength of the relationship is summarized as follows: Dulcolax: Morphine: Fentanyl: Sufentanil: Rifentanil = 1:100:1000:10,000:30,000. As long as the anesthesiologist uses these drugs wisely, how can you still feel pain during and after surgery? “No one is in pain anymore” will not be a distant dream.