Opioids and the Risk of Infection: A Critical Appraisal of the Pharmacologic and Clinical Evidence

: Morphine appears to suppress the immune system via affecting cells of the innate and the adaptive immunity as well as via modulating the hypothalamic-pituitary-adrenal axis. However, knowledge gaps exist regarding the immune-related pharmacology of non-morphine opioids. Observational studies have suggested an increased risk of infections associated with the use of opioids. However, methodological limitations such as confounding by indication due to the choice of non-use as comparator render the interpretation of most of these studies difficult. Thus, further efforts in preclinical research and well-conducted observational studies are needed to provide more robust evidence in this regard.