”These antidepressants are often prescribed “off-label,” says David Diaz, an assistant professor of clinical psychiatry at Indiana University School of Medicine. Meaning they’re being used in a way not specified in the [U.S.] Food and Drug Administration-approved packaging label. But “just because the medication is off-label does not mean it's being used experimentally,” Diaz says. “In many cases, it's the community standard.”
With 118 million prescriptions of antidepressants written a year, it is the third most common drug class prescribed in this country. It is estimated that one in five prescriptions are written off-label. Diaz estimates that one-third or more of antidepressant prescriptions are for off-label uses.
Antidepressants and Chronic Pain
Tricyclic antidepressants (TCAs) are older antidepressants that have fallen into disfavor because of the high doses it requires for effective action against depression. Often these doses induced sleepiness and fatigue. But TCAs are being used for another purpose: to reduce chronic pain in sufferers.
The funny thing is that researchers don’t know exactly how these drugs work but there is a theory. The theory posits that TCAs don’t block the pain at the receptor level, but that it modulates the way your brain processes the pain signal.
So this class of drugs has been found to be effective in treating neuropathic pain, pain typically caused by nerve damage or other nerve problems. Neuropathic pain is often unresponsive to traditional painkillers.