How do they work?
How antidepressants relieve pain is not completely understood. It is known that antidepressants alter neurotransmitter activity; it is thought that that this is the mechanism through which pain is modified. Different classes of antidepressants affect different neurotransmitters, including acetylcholine, norepinephrine, serotonin or combinations.
Pain relief, however, isn’t necessarily immediate and may take weeks to begin. One-third of patients diagnosed with neuropathic pain report moderate (or better) relief of pain with the use of antidepressants. In many cases, the dose used for pain relief may be lower than the dose typically used for treating depression. As a common side effect of antidepressants, somnolence (or drowsiness) may improve the ability to sleep in patients. Similarly, they may be a good choice if you are suffering from both depression and chronic neuropathic pain.
Lunn MPT, Hughes RAC, Wiffen, PJ. Duloxetine for treating painful neuropathy, chronic pain or fibromyalgia
. The Cochrane Collaboration. 2014 Jan 3. doi: 10.1002/14651858.CD007115.pub3
Saarto T, Wiffen PJ. Antidepressants for neuropathic pain.
The Cochrane Collaboration. 2012 Aug 15. doi:10.1002/14651858.CD005454.pub2#sthash.zFMuncTW.dpuf