Table 9.
Immunological effects of opioids
| Opioids | Immunological effects | 
| Morphine | Decreased NK cell cytotoxicity[131]; Impaired intestinal barrier function[140] | 
| Fentanyl and sufentanil | Decreased NK cell cytotoxicity[141]; Inhibition of cellular and humoral immunity[141] | 
| Tramadol | Reverse the immunosuppression after surgery[142] | 
NK: Natural killer.