The findings can't prove that the painkillers, called non-steroidal anti-inflammatory drugs, or NSAIDs, stop antidepressants from working, the authors said. But the possible link is something for patients with depression - and the doctors treating them - to think about when treating pain and inflammation, researchers report in Proceedings of the National Academy of Sciences, or PNAS.
"This is certainly something that clinicians and individuals should be keeping in mind," Jennifer Warner-Schmidt, the study's lead author from The Rockefeller University in New York City, told Reuters Health.
"If you're taking an SSRI antidepressant and it's not working so well for you, one possibility could be that the anti-inflammatory drugs are having an effect there," she said.
By analyzing the brains and behavior of mice treated with Celexa, a drug from the class of antidepressants called selective serotonin reuptake inhibitors, or SSRIs, Warner-Schmidt and her colleagues found that mice treated with Celexa and an NSAID had lower levels of the antidepressant in their blood than those that were only given Celexa.
Mice that were given a painkiller and antidepressant also did worse on tests measuring their stress and depression than those who just took the antidepressant.