Understanding TENS Helps Clinicians to More Effectively Support Patient Decision Making

Non-pharmacological strategies are taking on a growing place in pain management. In this context, transcutaneous electrical nerve stimulation, commonly known as TENS, is drawing renewed attention. Despite more than fifty years of research, its clinical effectiveness continues to provoke debate. Yet recent evidence shows that when this modality is properly understood and correctly applied, it can genuinely contribute to pain relief and to improved functional participation. For clinicians, understanding the mechanisms underlying TENS and the factors that shape its effectiveness allows for more accurate support of patient decision making and helps promote treatment adherence.

1- Back to basics, the gate control theory

TENS is based on a concept introduced in the 1960s: the gate control theory proposed by Melzack and Wall. This model transformed the understanding of pain by demonstrating that nociceptive signals do not travel directly from the periphery to the brain. Rather, they pass through a modulatory center within the spinal cord, where they can be either amplified or attenuated.

When a mild electrical current is applied to the skin, TENS activates nerve fibres associated with tactile and pressure sensations. These fibres conduct information more rapidly than nociceptive fibers, and their activation contributes to the “closing of the gate” to incoming pain signals, thereby reducing the amount of nociceptive input that reaches the brain.

Most individuals perceive a comfortable tingling or vibrating sensation beneath the electrodes. This sensation reflects the activity of fibers that temporarily inhibit the transmission of pain impulses. In essence, TENS diminishes nociceptive signaling before the brain can interpret it.

2- Endorphin release

The effects of TENS extend beyond the spinal gate. Electrical stimulation also elicits a chemical response, prompting the brain and spinal cord to release endogenous analgesic substances such as endorphins.

These molecules act on the same receptors targeted by certain opioid medications, yet without producing their adverse effects. Research by Vance and colleagues indicates that the mechanisms engaged by TENS vary according to stimulation frequency. Low-frequency TENS promotes the release of endorphins, producing a more generalized and longer-lasting analgesic effect. High-frequency TENS, in contrast, acts on distinct neural circuits that inhibit pain more rapidly.

Together, these mechanisms support the nervous system in regaining partial control over pain, which helps explain why some individuals experience relief that persists after the stimulation session.

3- Why stydy results vary

Studies and systematic reviews on TENS frequently report heterogeneous findings. This variability largely reflects differences in how the modality is applied. Parameters such as intensity, frequency, duration, electrode placement and individual patient characteristics all influence treatment outcomes. These sources of variation help explain why some trials demonstrate marked benefits while others remain inconclusive.

Intensity consistently emerges as the most critical parameter. For TENS to be effective, the stimulation must be sufficiently strong to generate a distinct yet comfortable sensation. If the intensity is too low, it will not activate the spinal gating mechanism nor promote the release of endogenous endorphins. Clinicians typically advise patients to increase the current until a stable, non-painful tingling is perceived, and to readjust it whenever the sensation diminishes.

With repeated use, the nervous system may gradually adapt to stimulation, which can reduce its analgesic effect. Modifying the frequency, duration, or electrode placement often helps re-establish an adequate therapeutic response.

Patient adherence is equally crucial. TENS is not a modality that can be prescribed and then left unattended. Individuals who understand when and how to use their device generally adjust the stimulation more effectively and obtain more meaningful outcomes. Conversely, insufficient instruction or follow-up often results in early discontinuation, which can be mistakenly interpreted as a lack of therapeutic efficacy.

4- What recent research shows

Recent studies offer more compelling evidence of TENS effectiveness when the modality is applied appropriately. A 2022 meta-analysis conducted by Johnson and colleagues reported significant pain reduction across several conditions, including postoperative pain, knee osteoarthritis, chronic low back pain, diabetic neuropathy and fibromyalgia.

In a separate study involving women with fibromyalgia, Vance and his team observed that participants who experienced improvement during the initial session were also those who showed the greatest benefit after several weeks of treatment. This finding suggests that early response may serve as a predictor of longer-term outcomes and underscores the importance of early follow-up and professional support.

Together, these results indicate that TENS can be effective when intensity, frequency and clinical guidance are optimally aligned.

5- The clinician's role

Although TENS can be used autonomously, its effectiveness relies heavily on the education and support provided by health professionals. The clinician must first assess whether TENS is suitable for the patient’s clinical presentation.

Clinicians also play a central role in shared decision making. They outline the expected benefits, the limitations and the possibility that relief may be partial or temporary, thereby helping patients develop realistic expectations and reinforcing therapeutic trust.

In addition, clinicians guide patients in electrode placement, in adjusting intensity and frequency and in identifying the most appropriate moments to use the device.

Ultimately, TENS achieves its full therapeutic value when integrated into an active and collaborative clinician–patient relationship.

6- A tool for autonomy and participation

When integrated into a multimodal treatment plan, TENS offers patients a concrete means of influencing their pain. This sense of control contributes meaningfully to adaptation and overall well-being. Although TENS does not replace core interventions such as exercise, rehabilitation or psychological approaches, it serves as a complementary modality that helps patients remain active.

By supporting patients in understanding how TENS functions and how to adjust its parameters, clinicians foster autonomy and strengthen shared decision making.

Ultimately, understanding TENS involves guiding patients toward informed choices that enhance their autonomy and their capacity to live well despite pain.

References 

Travers, M. J., O’Connell, N. E., Tugwell, P., Eccleston, C., & Gibson, W. (2020). Transcutaneous electrical nerve stimulation (TENS) for chronic pain: The opportunity to begin again. The Cochrane Database of Systematic Reviews, 2020(4), ED000139. https://doi.org/10.1002/14651858.ED000139

Johnson, M. I. (2021). Resolving long-standing uncertainty about the clinical efficacy of transcutaneous electrical nerve stimulation (TENS) to relieve pain: A comprehensive review of factors influencing outcome. Medicina, 57(4), 378. https://doi.org/10.3390/medicina57040378

Johnson, M. I., Paley, C. A., Jones, G., Mulvey, M. R., Wittkopf, P. G., & Eardley, W. J. (2022). Efficacy and safety of transcutaneous electrical nerve stimulation (TENS) for acute and chronic pain in adults: A systematic review and meta-analysis of 381 studies (BMJ Open 2022;12:e051073). BMJ Open, 12(12), e051073. https://doi.org/10.1136/bmjopen-2021-051073

Vance, C. G. T., Dailey, D. L., Chimenti, R. L., Van Gorp, B. J., Crofford, L. J., & Sluka, K. A. (2022). Using TENS for pain control: Update on the state of the evidence. Medicina, 58(10), 1332. https://doi.org/10.3390/medicina58101332

Vance, C. G. T., Zimmerman, M. B., Dailey, D. L., Rakel, B. A., Geasland, K. M., Chimenti, R. L., Williams, J. M., Golchha, M., Crofford, L. J., & Sluka, K. A. (2021). Reduction in movement-evoked pain and fatigue during initial 30-minute transcutaneous electrical nerve stimulation treatment predicts TENS responders in women with fibromyalgia. Pain, 162(5), 1545–1555. https://doi.org/10.1097/j.pain.0000000000002144

Vance, C. G. T., Dailey, D. L., Rakel, B. A., & Sluka, K. A. (2014). Using TENS for pain control: The state of the evidence. Pain Management, 4(3), 197–209. https://doi.org/10.2217/pmt.14.13