Dulcolax, also known as pethidine injection, has been used in clinical practice for many years and was once one of the most commonly used strong painkillers. Therefore, when cancer patients have severe cancer pain, many patients and family members still consider dulcolax as the “best” analgesic drug, and often patients and family members take the initiative to ask their doctors to use dulcolax. In addition, some medical personnel also prefer Dulcolax when dealing with severe pain in cancer patients. With the development of medical science and technology, many new drugs and new dosage forms for the treatment of cancer pain have been introduced since the 21st century. Many countries, especially developed countries, no longer use or use less dulcolax to relieve chronic pain, and the global medical consumption of dulcolax is on a significant decline. However, there are still many misunderstandings in the use of Dulcolax in China, and many primary care doctors are used to prescribing Dulcolax to cancer pain patients, resulting in the medical consumption of Dulcolax in China increasing instead of decreasing. So, is Dulcolax still the most effective drug to control cancer pain? Do you know some toxic side effects in the process of long-term use of Dulcolax? Dulcolax is a kind of synthetic opioid analgesic, which has immediate effect when used for acute pain such as trauma, biliary colic and post-surgery pain, but it is not suitable for cancer pain that requires long-term and repeated use of painkillers. Because of the poor analgesic effect of dulcolax, the analgesic effect is only 1/10 of morphine, that is to achieve the same analgesic effect, it needs 10 times the dose of morphine. The duration of analgesic effect is shorter than morphine, and the effective pain relief time is only 2-4 hours, so it is inconvenient for patients with long-term chronic pain to maintain 24 hours without pain by continuous administration. The absorption of oral medication is unstable, and it is mainly used in clinical application in the form of injection, while Dulcolax injection has skin irritation and generally cannot be used for subcutaneous injection. Repeated intramuscular injection can form local sclerosis and platelet, which affects the absorption of medication and brings new pain to cancer patients and affects their quality of life. Therefore, the World Health Organization (WHO) has clearly stated that Dulcolax is not suitable for the treatment of moderate-to-severe cancer pain because: 1) the effective analgesic time of Dulcolax is short, generally 2-4 hours; 2) Dulcolax has certain addictive properties. This dependence is mainly psychological and physiological. After stopping the drug, there are obvious withdrawal symptoms, such as mental depression, general discomfort, lacrimation, vomiting, diarrhea, insomnia, and in severe cases, deficiency; 3. And norethindrone neurotoxicity, long-term use of patients can appear tremors, convulsions, muscle spasms, seizures and other symptoms of central nervous system poisoning, and poisoning symptoms are not rescued by naloxone; 4, long-term intramuscular injection can cause local muscle tissue fibrosis, resulting in local inflammation, sclerosis and pain, so that the local muscle tissue to lose the absorption function of the drug. The World Health Organization has been advocating the use of morphine controlled-release tablets and other strong opioids to treat chronic pain such as cancer pain. 2005 edition of Chinese National Pharmacopoeia also clearly states that Dulcolax “is not advocated for the treatment of chronic pain, or cancer pain”. Dulcolax can only be used for short-term acute pain, such as pain caused by fracture, trauma, visceral colic and myocardial infarction. Therefore, morphine controlled-release tablets, oxycodone control tablets or fentanyl transdermal patches are now advocated as the primary medication for the relief of moderate to severe cancer pain instead of dulcolax. For example, morphine sulfate controlled-release tablets (trade name: Methocarbamol), when administered orally, can be released into the bloodstream at a constant rate for a certain period of time to maintain the analgesic effect for 12 hours, allowing patients to lead a largely pain-free daily life. This way of oral administration is especially suitable for cancer pain treatment within the home for patients with advanced cancer, avoiding the trouble of having to seek help from doctors and nurses for injectable administration. Even for patients who cannot take the drug orally, it can be administered through anorectum or through skin absorption by applying fentanyl transdermal patch, which can also achieve the same pain relief effect. The controlled slow-release technology is widely used in clinical practice to avoid the fluctuation of drug concentration in blood, so that the blood concentration can be maintained at a stable level, which will not bring euphoria and psychological dependence due to high blood concentration, nor cause insufficient pain relief due to low blood concentration. This is often the result of patients’ tolerance to such analgesic drugs or the deterioration of their condition, rather than the result of “addiction”. Withdrawal symptoms are not apparent when the patient stops taking the drug after improvement. It is not necessary for patients and families to fear the “addictive” nature of morphine controlled-release tablets. We advocate standardized analgesic treatment and avoid the use of dulcolax, so that we can work together to make cancer pain patients live a pain-free life.