Adjuvant analgesics represent a diverse group of drugs that were originally developed for a primary indication other than pain. Many of these medications are currently used to enhance analgesia under specific circumstances. The proper use of adjuvant drugs is one of the keys to success in effective pain management. Since adjuvant analgesics are typically administered to patients who take multiple medications, decisions regarding administration and dosage must be made with a clear understanding of the stage of the disease and the goals of care. The article discusses major classes of adjuvant analgesics, with the focus on the mechanism of action, clinical application, and risks and benefits associated with each particular class of adjuvants.