Drug-specific differences in the ability of opioids to manage burn pain.

•Burn injury profoundly alters the functional state of the immune system.•Burns alter the expression levels of receptor, effector, and signaling molecules.•These alterations may account for reduced potencies and effectiveness of opioids.•Opioids act to relieve pain via differential signaling molecules and pathways.•Different opioids differ in their ability to suppress the development of burn pain.