The Conversation: Many antidepressants for pain are not effective

Millions take antidepressants for chronic pain, but there’s little evidence the most commonly prescribed drugs work, researchers have told The Conversation.

About one in five people globally live with chronic pain. They are often prescribed antidepressants, but new research has shown that only one drug has been shown to work.

The authors of the analysis 178 relevant studies with a total of 28,664 participants. It is the largest-ever review of antidepressants for chronic pain and the first to include all antidepressants for all types of chronic pain.

Forty-three of the studies (11,608 people) investigated duloxetine. We found that it moderately reduces pain and improves mobility. It is the only antidepressant that we are certain has an effect. We also found that a 60mg dose of duloxetine was equally effective in providing pain relief as a 120mg dose.

The evidence for amitriptyline, citalopram, fluoxetine, paroxetine and sertraline was very poor, and no conclusions could be drawn about their ability to relieve pain.

This is particularly important as prescribing data shows 15,784,225 prescriptions of amitriptyline in the last year.

"It is reasonable to assume that a large proportion of these may be for pain relief because amitriptyline is no longer recommended for treating depression," the researchers noted.

The findings have formed the basis of new treatment guidelines in the UK. Duloxetine is now recommended for the treatment of chronic primary pain (i.e., pain with no apparent cause) as well as pain associated with neurological disorders.

"It’s important to bear in mind, though, that pain is a very individual experience, and the evidence in our review is based on groups of people. We acknowledge that certain drugs may work for people even when the research evidence is inconclusive or unavailable," stressed these researchers.

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