Limited evidence for benefit of amitriptyline for neuropathic pain and fibromyalgia in adults

Clinical question: 
How effective is amitriptyline for neuropathic pain and fibromyalgia in adults?
Bottom line: 
Amitriptyline probably does not work in neuropathic pain associated with HIV or treatments for cancer. Amitriptyline probably does work in other types of neuropathic pain (painful diabetic neuropathy, post-herpetic neuralgia, and post-stroke pain, and in fibromyalgia), though we cannot be certain of this. A best estimate is that amitriptyline provides pain relief in about 1 in 4 (25%) more people than does placebo (NNT* = 4.6 [95% confidence interval 3.6Ð6.6]), and about 1 in 4 (25%) more people than placebo report having at least 1 adverse event, probably not serious but disconcerting.*NNT = number needed to treat to benefit 1 individual.
There were no studies that could provide an answer that was trustworthy or reliable because most studies were relatively old, and used methods or reported results that we now recognise can make benefits seem better than they are.
Amitriptyline is a tricyclic antidepressant that is widely used to treat chronic neuropathic pain and fibromyalgia, and is recommended in many guidelines. These types of pain can be treated with antidepressant drugs in doses below those at which the drugs act as antidepressants.
Review CD#: 
February, 2013
Authored by: 
Brian R McAvoy