When other, more widely used painkillers are ineffective in treating chronic pain, doctors will occasionally prescribe antidepressants. But according to recent study, not all antidepressants work to reduce pain as intended.

For the study, published February 1 in the BMJ, researchers collected information from 156 clinical trials involving more than 25,000 people who received either an antidepressant or a placebo to treat chronic pain. Twenty-six systematic reviews were analyzed for the study. Eight different antidepressants were evaluated for potential efficacy in treating a wide range of chronic conditions, including back pain, migraine, rheumatoid arthritis and fibromyalgia, using a pain scale of 0 to 100.

There was not a single occasion when researchers could state with “high confidence” that a certain type of antidepressant had assisted in treating a specific condition’s chronic pain. According to Giovanni Ferreira, PhD, the study’s lead author and a researcher at the University of Sydney in Australia’s Institute for Musculoskeletal Health, there were only four instances where researchers could say with “moderate certainty” that a specific kind of antidepressant might treat a specific kind of chronic pain.

Dr. Ferreira notes that the majority of research that have looked into how well antidepressants work for chronic pain are tiny and of extremely poor quality. “This field needs better science,”

The Best Research on SNRI Antidepressants for Treating Chronic Pain

In the recent study, all four situations in which researchers came to the conclusion that antidepressants were effective for treating chronic pain used medications from the class of pharmaceuticals known as serotonin and norepinephrine reuptake inhibitors (SNRIs). By raising serotonin and norepinephrine levels in the brain, these medications reduce depressive symptoms. Norepinephrine helps increase focus and energy, and serotonin helps regulate mood.

In the BMJ analysis, SNRIs were discovered to lessen postoperative pain, neuropathic pain, and chronic back pain symptoms.

Only “poor certainty” evidence was found to support the use of SNRIs for pain brought on by breast cancer therapy, persistent pain brought on by depression, and pain brought on by knee arthritis.

They also discovered “poor confidence” proof for two other antidepressant classes. Tricyclic antidepressants (TCAs) may provide pain relief for neuropathic pain, chronic tension headaches, and irritable bowel syndrome. SSRIs, or selective serotonin reuptake inhibitors, can lessen chronic pain brought on by depression.

According to Chad Brummett, MD, co-director of the Opioid Prescribing Engagement Network and professor of anesthesiology at the University of Michigan in Ann Arbor, who was not involved in the new study, “antidepressants that act on norepinephrine levels in the brain and spinal cord are generally more useful than conventional antidepressants that act only on serotonin.”

Therefore, the finding of superiority of serotonin and norepinephrine reuptake inhibitors (SNRIs) over selective serotonin reuptake inhibitors (SSRIs) is “logical and consistent with the approach of most pain physicians,” Brummett said.

Antidepressants are frequently recommended for chronic pain, and patients are more likely to take these medications for this reason than for their advantages to their mental health, according to prior study. According to one analysis of prescription data from the United States, the United Kingdom, and Taiwan, up to 68 percent of antidepressant prescriptions were made for the treatment of chronic pain. The study revealed that the most often prescribed antidepressants for chronic pain in the United States were SSRIs, which may not always be beneficial, according to a recent BMJ study.

This is taking place in part because other prescription painkillers are ineffective, have risky side effects, or have a high potential for addiction. Opioids can be useful but run the danger of becoming addictive. Nonsteroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen and naproxen, can occasionally reduce pain, but prolonged usage raises the risk of renal issues, heart attacks, and strokes. Acetaminophen, another popular over-the-counter pain reliever, can lessen some types of pain but comes with a risk of liver damage with prolonged usage.

According to Christopher Goodman, MD, a clinical assistant professor of medicine at the University of South Carolina, studies on the use of antidepressants in treating chronic pain generally reveals limited advantages, but that is also true of almost every drug for treating chronic pain.

According to Dr. Goodman, “antidepressants are generally safe—certainly safer than opioids and without the renal and cardiac hazards of NSAIDs.” They may be suitable for those with overlapping symptoms of depression and chronic pain.

One drawback of the study is that different techniques for measuring pain and different treatment choices for various types of chronic pain were employed in each of the smaller studies included in the analysis. This may have made it challenging to identify tiny but significant treatment advantages. Additionally, the investigation did not look at how frequently those using antidepressants for chronic pain also had a psychiatric disorder that may benefit from these medications.