Animal studies have shown that some opioid medications have immunosuppressive effects. The drugs interfere with the production of bacteria-killing immune cells, reduce the innate immune response, and inhibit the production of antibodies and cytokines. Previous human studies have shown that opioid medications increase the risk for infection in hospitalized patients after surgery or during treatment for burns or cancer. Other studies suggest an increased risk for serious infections in certain high-risk outpatients.
Now, the new study strengthens the evidence that the immune-suppressing effects of opioids extend to humans.
"[W]e found that current opioid use was strongly and consistently associated with the risk for [invasive pneumococcal disease (IPD),] and that the association was strongest for long-acting and high-potency formulations, opioids previously described as immunosuppressive, and high-dose opioids," write Andrew Wiese, PhD, from the Department of Health Policy at Vanderbilt University Medical Center, Nashville, Tennessee, and colleagues.