The French study adds to a growing body of evidence questioning the effectiveness and safety of steroid injections into the spinal area.

A 2015 report by the Agency for Healthcare Research and Quality (AHRQ) found little evidence that epidural steroid injections were effective in treating low back pain. Researchers said the injections often provide immediate improvements in pain and function, “but benefits were small and not sustained, and there was no effect on long-term risk of surgery.”

A 2014 study by the AHRQ also found that epidural injections did little to relieve pain in patients with spinal stenosis.

Epidural injections, which have long been used to relieve pain during childbirth, are increasingly being used as an alternative to opioids in treating back pain. The shots have become a common and sometimes lucrative procedure at many pain management clinics, where costs vary from as little as $445 to $2,000 per injection.

The Food and Drug Administration has never approved the use of steroids to treat back pain, but several million epidural steroid injections are still performed “off label” in the U.S. annually.

The American College of Physicians (ACP) recently released new guidelines saying there was little evidence that steroid injections are effective as a treatment for low back pain.

“Moderate-quality evidence showed no differences in pain between systemic corticosteroids and placebo and no to small effect on function in patients with radicular low back pain,” the ACP said.

Lower back pain is the world's leading cause of disability. Over 80 percent of adults have low back pain at some point in their lives.