Treating Back Pain with Antidepressants
Doctors sometimes prescribe antidepressant medicine to treat chronic low back pain (LBP). No one is sure how it works. But certain types of antidepressants do seem to help relieve pain for some other conditions. And chronic LBP is so hard to treat, some patients will try anything that might help.

These authors looked at the research to judge whether antidepressants work on chronic LBP. Results were checked for two kinds of antidepressants. The authors narrowed the field to seven good studies. Tricyclic and tetracyclic antidepressants did give seem to give pain relief. It was unclear if they helped people move and do daily tasks better. Antidepressants known as SSRIs did not show any pain relief in these studies.

None of the studies shed any light on why antidepressants might relieve LBP. The authors note that the pain relief doesn't seem to be because the patients are necessarily any happier. The authors warn that even if they work, antidepressants won't be a good treatment for everyone with LBP. Antidepressants can have some serious side effects. Still, the authors feel there is enough evidence to do larger studies on the use of antidepressants for LBP.
References
Thomas O. Staiger, MD, et al. Systematic Review of Antidepressants in the Treatment of Chronic Low Back Pain. In Spine. November 15, 2003. Vol. 28. No. 22. Pp. 2540-2545.