There’s not a lot of good research on TENS, and some of the results are conflicting. But there is evidence that it may work for some people. The amount of pain relief it provides, and for how long, varies from person to person.
Generally, TENS may provide pain relief at first for many people who try it. But after using it for a few months, it appears to become less effective. It’s best to think of TENS as something to try in addition to other methods of managing pain.