Patients prescribed fentanyl, morphine, or codeine in the 100 days before being hospitalized have an increased risk for pneumonia while in the hospital, according to research presented at the American Academy of Pain Medicine (AAPM) 2017 Annual Meeting.

The relationship is probably due of immune suppression and not respiratory depression, the researchers speculate.

“This is just a signal finding, but it makes me think that in vulnerable patients, such as those who are already immune suppressed, including HIV patients and those on biologics, we might want to weigh immunosuppressive effects of opioids when we make decisions about how we prescribe,” said lead researcher, Andrea Rubinstein, MD, Permanente Medical Group, Santa Rosa, California.