Acetaminophen. Acupuncture. Massage. Muscle relaxants. Cannabinoids. Opioids. The list of available treatments for low back pain goes on and on. But there’s not good evidence that these treatments actually reduce the pain, according to a new study that summarized the results of hundreds of randomized trials.

Low back pain affects an estimated one in four American adults and is the leading contributor to disability globally. In most diagnosed cases, the pain is considered “nonspecific,” meaning it doesn’t have a clear cause. That’s also partly what makes it so hard to treat.

In the study, published on Tuesday in the journal BMJ Evidence-Based Medicine, researchers reviewed 301 randomized trials that compared 56 noninvasive treatments for low back pain, like medications and exercise, with placebos. They used a statistical method to combine the results of those studies and draw conclusions, a process known as a meta-analysis.

The researchers found that only one treatment — the use of nonsteroidal anti-inflammatory drugs, or NSAIDs, like ibuprofen and aspirin — was effective at reducing short-term, or acute, low back pain. Five other treatments had good enough evidence to be considered effective at reducing chronic low back pain. These were exercise; spinal manipulation, like you might receive from a chiropractor; taping the lower back; antidepressants; and the application of a cream that creates a warming sensation. Even so, the benefit was small.

“The big takeaways from this paper are that low back pain is exceptionally difficult to treat,” said Steve Davidson, the associate director of the N.Y.U. Pain Research Center, who was not involved in the study. “There are a few treatments that they found that were effective, but those that were effective are marginally clinically effective.”

There was good evidence, for example, that exercise can reduce chronic back pain. But it only reduced the intensity of pain by an average of 7.9 points on a 0-to-100 pain scale — less than what most doctors consider to be a clinically meaningful difference.