If you’re considering using a TENS unit to address your chronic pain, you are probably curious about the most important question regarding any therapy: does it work?
While TENS units may not be the right tool for every single pain-related condition, the short answer is that yes, TENS units work to reduce some kinds of pain. The long answer is that there is a lot of debate in the scientific community regarding where TENS is the most helpful.
All of the research regarding TENS agrees on the basics: TENS can, in theory, reduce pain. The practical details are subject to much debate, but the consensus is that there are at least a handful of applications in which TENS can reduce pain in practice, too.
A meta-analysis of scientific literature published in 2008 in the Journal of Current Rheumatology Reports states that there is a continuing flow of new scientific evidence which supports the use of TENS technology for analgesia in several conditions.
The fact that the paper was a meta-analysis means that it examined many other scientific reports on the efficacy of TENS to make a big-picture summary. So, if the meta-analysis claims that there is evidence in favor of TENS, it’s a lot like saying a bunch of different scientific papers support TENS for analgesic use.
There is a subtlety in the paper’s findings, however. The paper states that the intensity of the current is the single biggest factor in patients experiencing pain reduction. So if you are having trouble getting your TENS unit to reduce your pain, you may need to play with the intensity by either increasing it or decreasing it.
A second meta-analysis found similar results as the first. Notably, this second meta-analysis claimed that many instances of studies which found negative results in TENS use for analgesia — which is to say, studies that found TENS was ineffective — were plagued by methodological problems and small sample sizes.
In other words, many of the negative scientific findings may have been incorrect. Importantly, both of the meta-analyses only examined the efficacy of TENS on musculoskeletal pain.
Neurological pain or organ pain were not assessed in any capacity, and it appears as though no subsequent researchers have shed much light on the issue. This means that you may want to avoid using your TENS unit on your organ pain or nerve pain.
A 2010 study from the journal Neurology found evidence for mixed efficacy of TENS units. Specifically, the study found that TENS units were ineffective for treating chronic back pain.
Interestingly, the study also said that TENS units were effective for diabetic neuropathy, which contradicts prior research indicating that TENS is not helpful for nerve pain.
This means that the study essentially said the opposite as other studies about what they thought TENS was beneficial for and what they thought TENS was not helpful for.
In the study, the researchers claimed that evidence in favor of using TENS for chronic back pain was typically not methodologically sound and that the studies were often conducted with only a small number of participants. Given that several other studies contradict this claim, it may be safe to discard their view.
What do other researchers say that is critical about TENS? Another meta-analysis is ambiguous regarding the efficacy of TENS in allaying lower back pain. In this meta-analysis, researchers found a mixture of conflicting reports.
Some of the reports claimed that patients were helped by TENS. Other reports claimed they were not. After poring through all of their data, the authors of the meta-analysis had only a few tentative conclusions.
The first conclusion was that TENS probably does not restore functionality or the range of motion in people who have chronic back pain.
This is understandable, as TENS makes no physical alterations to the muscle tissue or bone structure which might restore functionality. It is probable that this conclusion is sound and there are few researchers who dispute it, even if they are huge proponents of TENS.
Their second conclusion is that TENS may not lead to a higher quality of life for all patients with chronic back pain. To arrive at this conclusion, the authors examined two other studies, both of which had many participants and a good methodological basis.
One study claimed that TENS did not improve the quality of life of patients with chronic back pain. The study claimed this with “moderate” certainty, which, in the scientific parlance, is difficult to parse. It is unlikely that the results are spurious, but the door is still open for the results to be clarified and refuted by a later study.
The other study claimed that TENS significantly improved patients’ quality of life in a broad swath of criteria.
Given the level of scientific disagreement regarding TENS’ efficacy, it might seem as though TENS is ineffective. This isn’t the case, however. Scientific disagreements are never as simple as one side believing X and the other side believing Y.
Most of the disagreement over TENS’ efficacy is over the situations in which it is the most helpful to patients. All of the researchers in the TENS studies which we have discussed in this article reported that the evidence they examined found TENS to be effective in at least a few different contexts.
So, what is the most charitable verdict for TENS? TENS is broadly effective, but its efficacy varies widely across patients and protocols. The idea that TENS is a sham treatment or that it is actively harmful are not supported by any scientific evidence whatsoever.
This means that patients should be ready to spend a lot of time honing in their TENS protocol if they want to get the most pain relief.
Likewise, patients may want to check out the scientific literature to look at the methods sections of studies that examined using TENS units on pain that they experience.
If you look at the methods section of articles which found the TENS protocol to be helpful for the patients, you have a good chance of finding something which will work for you.