If you suffer from physical and emotional pain and take medication for both, common pain pills could make antidepressants less effective, according to a study published in the Proceedings of the National Academy of Sciences.

The drugs included in the study were non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen and naproxen, and selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant including Lexapro, Paxil, Prozac and Zoloft.

For the study, scientists looked at data from 1,546 participants in a 12-week Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study performed by the National Institute of Mental Health. The STAR*D study asked participants to report on their NSAIDs use. (Patients weren’t asked to specify how often they used the painkillers or for how long.)

Researchers found that antidepressants were effective for 55 percent of participants who didn’t use NSAIDs. For those who took NSAIDs, antidepressants were only 40 percent effective.

What the data suggested is that anti-inflammatory drugs may be one possibly preventable reason for antidepressant treatment resistance, said Jennifer Warner-Schmidt, PhD, of The Rockefeller University in New York City and lead study author.

But this didn’t mean that popping a single aspirin tablet would ruin your antidepressant regimen, Warner-Schmidt explained. The problem might result more from people’s continuous use of NSAIDs for chronic pain or arthritis.

A previous mice study to test the link between NSAID use and antidepressant effectiveness seemed to support the STAR*D findings. But more research is needed to confirm the quantity of NSAIDs people would have to take to render antidepressants ineffective, researchers said.

What might this mean for people currently on depression drug therapy? Well, if your antidepressants don’t seem to be working, check with your doc to see if your use of NSAIDs might be to blame.

Click here for another possible connection between painkillers and mental health.