Hundreds of thousands of Britons are taking antidepressants for chronic pain without enough evidence they work, according to a large study.
Researchers looked at drugs commonly prescribed by the NHS including amitriptyline, duloxetine, fluoxetine (Prozac), citalopram, paroxetine (Seroxat) and sertraline.
They concluded only duloxetine had robust evidence for pain relief.
The National Institute for Health and Care Excellence (Nice) recommends them as an option where the root cause is unknown, including for some cancer pain, and conditions that can cause neuropathic pain, such as stroke.
It said it had reviewed the study in detail but decided an update to guidelines was currently unnecessary.
The research looked at 176 trials and almost 30,000 patients, and included institutions such as University College London, and the universities of Bath, Bristol and Southampton.
It also raised concerns about a lack of long-term data on the drugs’ safety.
Lead author Professor Tamar Pincus said the findings raised a “global public health concern”, with people prescribed the drugs without “sufficient scientific proof they help, nor an understanding of the long-term impact on health”.
“Our review found no reliable evidence for the long-term efficacy of any antidepressant, and no reliable evidence for their safety for chronic pain at any point,” she said.
“Though we did find that duloxetine provided short-term pain relief for patients we studied, we remain concerned about its possible long-term harm due to the gaps in current evidence.”
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Professor Pincus said there were around 15 million low-dose amitriptyline prescriptions in England in 2020 to 2021 – and hundreds of thousands likely taking it for pain – but the drug is “probably not very healthy”.
“The fact that we don’t find evidence whether it works or not is not the same as finding evidence that it doesn’t work,” she added.
“We don’t know – the studies simply are not good enough and, similarly, we don’t know whether it harms or not.”
Patients ‘shouldn’t panic’
The authors are urging people to continue drugs they have been prescribed and to raise any concerns with their GP.
Dr Ryan Patel, from King’s College London, explained that antidepressants are prescribed for pain because “the systems that regulate mood and pain overlap considerably”.
He said the study showed “when clinical trials are designed poorly under the assumption that everyone’s experience of pain is uniform, most antidepressants appear to have limited use for treating chronic pain”.
The chair of the Royal College of GPs said doctors aim to treat chronic pain with a mix of psychological, pharmacological and physical treatments – and to prescribe “the lowest dose of medicines, for the shortest time”.
Professor Kamila Hawthorne said patients “shouldn’t panic” and reiterated they should continue with their medication until they’ve discussed things with their GP.
Nice said its recommendation for antidepressants as a treatment option came after a thorough look at the benefits and harms.
It said evidence showed they can help with “quality of life, pain, sleep and psychological distress, even in the absence of a diagnosis of depression”.