Anticonvulsant medicines such as gabapentin are ineffective in chronic low back pain and sciatica and come with a high risk of adverse effects, a new Australian review shows.

While anticonvulsants may have a role in neuropathic pain, there is high quality evidence that they are no better than placebo for the treatment of low back pain or lumbar radicular pain, according to researchers at the University of Sydney.

Their review found nine randomised controlled trials comparing gabapentin, pregabalin or topiramate to placebo. For chronic low back pain there was high quality evidence showing that gapapentinoids did not reduce pain or disability in the short term (less than two weeks). Likewise, there was low quality evidence intermediate term (up to three months).

Topiramate had some evidence of efficacy on pain over the short term but no effect on disability.

For lumbar radicular pain, there was generally moderate-to high-quality evidence showing that anticonvulsants had no effect on pain or disability at all time points.

The review also found high level evidence supporting the risk of harms with anticonvulsant drugs. The most common adverse events reported in participants taking a gabapentinoid were drowsiness or /somnolence, dizziness and nausea.

The review authors said their findings supported guideline recommendations against the use of anticonvulsants in low back pain. But despite this, over 1.3 million prescriptions were written for the anticonvulsant medication pregabalin in Australia between 2013 and 2014, they noted.

“Clinically, GP prescription of medicines used to treat nerve pain, such as anticonvulsants, has increased by an astounding 535 per cent in the last ten years,” said study author, Associate Professor Christine Lin, Principal Research Fellow at Musculoskeletal Health at the University of Sydney.

“We have shown, with mostly high-and moderate-quality evidence, that common anticonvulsants are ineffective for chronic low back pain and lumbar radicular pain and are accompanied by increased risk of adverse events such as drowsiness or dizziness.

“There are also reports of suicidal ideation and misuse of these drugs.”

The research is reported in the Canadian Medical Association Journal.