Abstract: Adjuvant analgesics refer to a group of drugs that are used not only to treat certain diseases but also to induce analge-sia. Such drugs demonstrate different mechanisms based on the complexity of cancer pain. Thus, opioids, nonsteroidal drugs, and adju -vant analgesics are often combined to control cancer pain. According to the WHO three-step analgesic ladder, adjuvant analgesics can be used at any cancer stage, and the usage of these drugs combined with opioids can reduce the required dosages of these pain relievers, thereby alleviating the adverse reactions associated with opioid use. Moreover, these drugs are particularly suitable for neuropathic pain patients who are not fully sensitive to opioids. The commonly used adjuvant analgesics include antidepressants, anticonvulsants, local administration drugs, corticosteroids, and N-methyl-D-aspartate (NMDA) receptor antagonists. Various adjuvant analgesics also differ in usage and dosage based on primary disease treatment. Therefore, clinical doctors should determine the adverse reactions, proper dos -age, and subsequent amount of dosage to be added in a few days or weeks to achieve balance between the desired effect and adverse re -actions.