Antidepressants are drugs usually used to treat patients with depression. However, some antidepressants have been shown to be effective pain relievers. Though the U.S. Food and Drug Administration (FDA) has not approved most antidepressants for this purpose, they are often prescribed to relieve chronic pain, even in patients who do not have depression.

Studies have shown that tricyclic antidepressants (TCAs) – which appear to increase the levels of certain neurotransmitters that block pain signals – can relieve pain associated with numerous conditions, including the burning or searing pain related to nerve damage (neuropathic pain). Such pain may affect patients with diabetes, shingles, stroke or other conditions. TCAs also appear to be first-line medications for the management of fibromyalgia.

A group of antidepressants called selective serotonin and norepinephrine reuptake inhibitors (SSNRIs) appear to exert their effect by mechanisms similar to TCAs. The FDA has approved an SSNRI for relief of diabetic nerve pain.  

Other conditions that are sometimes treated with antidepressants include chronic fatigue syndrome, migraines and other headaches, cranial neuralgias, arthritis, back pain and pelvic pain.

The FDA has found that antidepressants increased the risk of suicidal thoughts and behavior in individuals with major depressive disorders and other psychiatric conditions, and ordered that warnings to this effect appear on the labeling of these medications. Patients on antidepressants should be closely monitored for any worsening of their condition, suicidal thoughts or behaviors or otherwise unusual behaviors.