A new study says opioids offer little chronic pain benefit and wane over time.

 The results come from a review of nearly 100 randomized trials published in the Journal of the American Medical Association.

The analysis found for adults with chronic pain, opioids offer narrow improvements over a placebo for pain and physical functioning, on average.

Those benefits also tend to decrease over time and come with the risk of side effects such as vomiting and constipation.

The analysis comes as federal agencies and other officials in recent years have been cracking down on opioids prescription