Commonly used painkillers such as aspirin can adversely impact the effectiveness of antidepressants belonging to the SSRI class of drugs.

In this study mice were given SSRIs with and without NSAIDs. The researchers assessed the performance of the mice in tasks sensitive to antidepressants and found that mice that were given NSAIDs did not perform well in these tasks.
These results compare well with a human study in which researchers reported that painkillers blunted the effectiveness of SSRIs and did not relieve the symptoms of depression. "If people out there are having trouble with SSRI efficacy and they happen to be taking anti-inflammatory drugs, they may want to speak with their clinician to evaluate whether they need to continue on the anti-inflammatory drugs, and if so, they may consider changing their antidepressant to a different class of antidepressant," Warner-Schmidt said.
The details of the study are published in the online edition of the Proceedings of the National Academy of Sciences.
Source-Medindia