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TENS

Pooled trials found TENS eased period pain against sham or no treatment, though sham-controlled reviews disagree, and lowered pain across conditions against placebo TENS at moderate certainty. Labor pain findings were mixed. Minor skin irritation is the common harm, and case reports describe interference with pacemakers and defibrillators.

Add to Bio HackChecked 2026-11-13
Status
A practice, not a regulated product. FDA classifies transcutaneous electrical nerve stimulators for pain relief as class II medical devices [1].
Also called
TENS, TENS unit, transcutaneous electrical nerve stimulation, TENS machine, electrical nerve stimulation, e-stim for pain, period pain TENS device, labor TENS
Practiced for
period pain, menstrual cramps, endometriosis pain, labor pain, back pain, fibromyalgia, chronic pain, nerve pain, arthritis pain, cutting down on pain pills

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help4

Reported risks2

What people practice it for, and what was found

Shown to help4

ModerateStudied in women

Period pain, compared with sham or no treatment pooled together

Shown to ease period pain in women by 1.39 points with high-frequency and 2.04 with low-frequency TENS, against sham or no treatment pooled together, at low certainty.

Compared with placebo TENS or no treatment, pooled together [5]

The numbers and sources
Effect
High-frequency TENS lowered pain against placebo or no treatment (MD -1.39, 95% CI -2.51 to -0.28, 10 trials, 345 women, I² 88%), as did low-frequency TENS (MD -2.04, 95% CI -2.95 to -1.14, 3 trials, I² 0%). High- and low-frequency TENS did not clearly differ (MD 0.89, 95% CI -0.19 to 1.96) [5].
Population
585 women aged 12 to 49 with primary dysmenorrhea in 20 trials [5].
Sources
[5]
Caveats
The Cochrane review pools placebo and no-treatment arms, so blinded and unblinded comparisons are mixed. Certainty was downgraded for risk of bias [5].
Moderate

Pain in many conditions, compared with placebo TENS

Shown to lower pain during or right after use against placebo TENS in adults with many kinds of pain, across 91 trials, at moderate certainty.

Compared with placebo TENS [8]; sham TENS [9]

The numbers and sources
Effect
Pain was lower during or immediately after TENS than with placebo (SMD -0.96, 95% CI -1.14 to -0.78, 91 trials, 4,841 people), and acute or chronic pain, diagnosis and risk of bias did not change the effect [8]. An overview of Cochrane reviews of chronic pain found one review with lower pain against sham (MD -1.58, 95% CI -2.08 to -1.09 on a 0 to 10 scale, 5 trials, 207 people), and rated all its evidence very low in quality [9].
Population
24,532 adults with pain in 381 trials [8]. 2,895 people in 51 trials across 8 Cochrane reviews [9].
Sources
[8], [9]
Caveats
Most trials were small, and effects were measured during or right after a session. The overview found too little usable data to report on lasting relief or daily function [9].
Moderate

Pain in many conditions, compared with usual treatments

Shown to lower pain during or right after use more than medicines or other usual treatments, across 61 trials in adults, at low certainty.

Compared with drug and non-drug treatments used as standard care [8]

The numbers and sources
Effect
Pain was lower during or immediately after TENS than with standard-care treatments (SMD -0.72, 95% CI -0.95 to -0.50, 61 trials, 3,155 people) [8].
Population
Adults with pain in 61 trials [8].
Sources
[8]
Caveats
Low certainty because of small trials [8].
ModerateVery common

Fibromyalgia pain with movement

Shown to lower pain with movement in women with fibromyalgia, by 1.0 point against placebo TENS and 1.8 points against no TENS, out of 10.

Compared with placebo TENS [12]; no TENS [12]; physical therapy alone [13]

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
After 4 weeks of home use during activity, pain with movement fell more with TENS than with placebo TENS (MD -1.0, 95% CI -1.8 to -0.2) or no TENS (MD -1.8, 95% CI -2.6 to -1.0), and fatigue with movement fell too. Global improvement was reported by 70% on TENS, 31% on placebo TENS and 9% with no TENS [12]. In a trial across 28 physical therapy clinics, adding TENS lowered pain with movement at day 60 (MD -1.2, 95% CI -1.6 to -0.7), and 41% against 13% had a reduction of 30% or more. At 180 days, 81% found TENS helpful [13].
Population
301 women with fibromyalgia on stable medicines [12]. 384 adults with fibromyalgia, 91% female [13].
Sources
[12], [13]
Caveats
The larger trial randomized clinics, not people, and had no placebo device [13].

Mixed results4

ModerateStudied in women

Period pain, compared with sham TENS

Mixed results: one review of sham-controlled trials found TENS eased period pain in women, while another found pain scores did not differ but fewer women needed pain pills.

Compared with sham TENS [2]; placebo TENS [3]; sham or placebo TENS in most trials, a placebo pill in one and usual NSAID use in one [4]

The numbers and sources
Effect
In 4 trials that all used sham TENS, pain was lower with TENS (SMD 1.384, 95% CI 0.505 to 2.262) [2]. In 9 trials against placebo, fewer women needed pain medicine (RR 0.43, 95% CI 0.30 to 0.63, moderate quality) and relief lasted longer, while pooled pain intensity did not differ (SMD -4.50, 95% CI -9.90 to 0.91) [3]. Across 13 trials, mostly against sham, pain scores were lower with TENS (MD -1.97, 95% CI -3.13 to -0.81, 8 trials, 398 women, I² 90%), fewer ibuprofen tablets were taken (MD -1.29, 95% CI -2.54 to -0.05), and scores for pain's effect on daily life did not differ (MD 0.01, 95% CI -0.37 to 0.40) [4].
Population
260 women with primary dysmenorrhea in 4 trials [2]. 530 women in 9 trials [3]. 779 women and girls aged 15 to 29 in 13 trials [4].
Sources
[2], [3], [4]
Caveats
Trials were small, heterogeneity was very high, and the reviews included different trials [3][4]. TENS produces a tingling that a sham device does not fully copy, so blinding may be imperfect.
ModerateStudied in pregnancy

Labor pain

Mixed results: a Cochrane review found little difference in labor pain ratings with TENS, while a later review of 26 trials found a small reduction in pain intensity.

Compared with routine care, other pain relief methods or placebo devices [6]; control groups the abstract does not describe [7]

The numbers and sources
Effect
Across 19 trials, pain ratings differed little between TENS and control groups. Women given TENS on acupuncture points were less likely to report severe pain (RR 0.41, 95% CI 0.32 to 0.55). Added to an epidural, TENS did not reduce pain, and it had no consistent effect on interventions or outcomes in labor. Most women who used TENS said they would use it again [6]. A later review found a small pooled reduction in pain intensity (RR 1.52, 95% CI 1.35 to 1.70) [7].
Population
1,671 women in labor in 19 trials, 15 with electrodes on the back [6]. 3,348 women in labor in 26 trials [7].
Sources
[6], [7]
Caveats
Most trials in the later review had a high risk of bias [7]. Use at home in early labor has not been studied [6].
Moderate

Chronic low back pain

Mixed results: placebo-controlled trials conflicted for chronic low back pain. A 2026 review found an effect only when stimulation was strong enough to feel clearly.

Compared with placebo TENS [10]; control or placebo groups [11]

The numbers and sources
Effect
Four high-quality trials gave conflicting results on pain against placebo, and two (410 patients) found no improvement in back function [10]. Across 29 studies, TENS had no overall effect on pain (d 0.16, 64 comparisons). Against control or placebo, trials using a clearly felt, adjusted intensity showed a larger effect (d 0.97, 95% CI 0.65 to 1.30) than trials using too little (d 0.30, 95% CI -0.11 to 0.72) [11].
Population
585 patients in 4 trials [10]. 29 studies [11].
Sources
[10], [11]
Caveats
The later review rated certainty low because of high risk of bias and heterogeneity [11].
LimitedStudied in women

Endometriosis pain

Limited evidence: one trial of 101 women found pelvic pain eased only when TENS was added to hormonal treatment. A before-and-after study found no significant pain change.

Compared with hormonal treatment alone [14]; the same women before using TENS [15]

The numbers and sources
Effect
Pelvic pain fell from 7.11 to 4.55 with TENS added to hormonal treatment (p < 0.001), with relief seen only in that group. Pain during sex improved in both groups [14]. In a study with 3 months without and 3 months with TENS, pain fell 2.29 points (p = 0.44), quality of life improved 16.57 points (p < 0.001) and daily ibuprofen fell 93 mg (p = 0.02) [15].
Population
101 women with deep endometriosis on hormonal treatment, for 8 weeks [14]. Women aged 18 to 45 with surgically confirmed endometriosis [15].
Sources
[14], [15]
Caveats
The trial abstract reports changes within each group, not a difference between them, and there was no sham [14]. The second study had no control group [15].

Not shown to help1

LimitedStudied in women

Period pain, compared with pain medicines and other treatments

Limited evidence: in single small trials, period pain did not differ between TENS and acetaminophen in women. Too few trials compared TENS with NSAIDs for pain.

Compared with acetaminophen [5]; acupressure [5]; interferential current therapy [5]

The numbers and sources
Effect
Pain did not differ between high-frequency TENS and acetaminophen (MD -0.98, 95% CI -3.30 to 1.34, 1 trial, 20 women) or low-frequency TENS and acetaminophen (MD -1.48, 95% CI -3.61 to 0.65). Nor did it differ against acupressure (MD -0.66, 18 women) or interferential current (MD -0.03, 95% CI -1.04 to 0.98, 2 trials, 62 women) [5].
Population
18 to 62 women per comparison [5].
Sources
[5]
Caveats
Very low certainty, from one or two trials per comparison [5].

Protocols studied

Period pain trials used 30-minute sessions at 2 to 120 Hz with electrodes on the lower abdomen or back, on painful days [4], and compared high-frequency with low-frequency TENS [5]. Labor trials mostly placed electrodes on the back, with some on acupuncture points or the head [6]. The pooled pain trials used strong but non-painful TENS at or near the site of pain [8]. The fibromyalgia trials used TENS for 2 hours a day during activity, at 2 to 125 Hz, at the strongest comfortable intensity, for 4 weeks [12] or 60 days and beyond [13]. The endometriosis trial added self-applied TENS to hormonal treatment for 8 weeks [14].

Risks

Reported risks2

LimitedVery common

Skin irritation and other minor side effects

Small trials found minor side effects such as skin irritation, in under 5% over 4 weeks in one fibromyalgia trial and 30% over 6 months in another.

The numbers and sources
How common
Very common: more than 1 in 10 people.
Effect
Over 6 months, 109 of 358 participants (30%) had minor adverse events [13]. Fewer than 5% had minor adverse events from TENS over 4 weeks [12]. Period pain trials reported itching at the electrodes, dizziness on first use, brief discomfort during stimulation in 10 of 12 women in one trial, and more pain in one [4]. Back pain trials reported minor skin irritation under the electrodes [10]. A large review found adverse events poorly reported, generally mild and no different from comparators [8]. Against NSAIDs for period pain, adverse effects did not differ significantly (OR 12.06, 95% CI 0.26 to 570.62, 2 trials, 88 women) [5]. A case report describes a delayed allergic reaction to electrode pads [16].
Population
358 adults [13]. 301 women [12]. Women in period pain trials [4][5]. Back pain trials [10]. 381 trials [8]. 1 patient [16].
Sources
[13], [12], [4], [10], [8], [5], [16]
Caveats
Rates in placebo groups were not given in these abstracts.
LimitedHow often is not known

Interference with pacemakers and defibrillators

Case reports: TENS interfered with cardiac pacemakers in two patients and caused false defibrillator alarms or shocks in two others.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
In two patients with pacemakers, a short ECG during TENS looked normal, while longer Holter monitoring showed interference with pacemaker function, which stopped after the pacemakers were reprogrammed [18]. In two patients with implanted defibrillators using a TENS device for back pain, the device's signal was read as ventricular fibrillation, and one received inappropriate pacing and shocks [19].
Population
2 patients with pacemakers [18]. 2 patients with implantable cardioverter-defibrillators [19].
Sources
[18], [19]
Caveats
Case reports give no rate.

Checked, no increase found1

Moderate

Serious harm

Not shown to cause serious harm: no serious adverse events from TENS were reported in large pain trials or in 19 labor trials, though many trials reported harms incompletely.

The numbers and sources
How common
How often is not known: the sources give no rate.
Effect
The large pain review found no serious adverse events [8]. Two fibromyalgia trials reported no TENS-related serious adverse events [12][13]. The labor review reported no adverse events, with little information on outcomes for mothers and babies [6]. Across 74 TENS trials, compliance with harms-reporting standards averaged 64.2% [17].
Population
381 trials [8]. 685 people with fibromyalgia [12][13]. 1,671 women in labor [6]. 74 trials [17].
Sources
[8], [12], [13], [6], [17]
Caveats
Incomplete harms reporting means rare events could be missed [17].

Claims tested and not found

  1. That TENS adds pain relief to an epidural in labor. A Cochrane review found no evidence that it reduced pain when used with an epidural [6].
  2. That TENS changes how labor goes. The same review found no consistent effect on interventions or outcomes in labor [6].
  3. That TENS improves back function in chronic low back pain. Two placebo-controlled trials of 410 patients found no improvement in back-specific function [10].

Related

Heat therapyNSAIDsAcetaminophenAcupuncturePhysical therapy and exercise therapy

Sources

  1. US Food and Drug Administration. 21 CFR 882.5890, Transcutaneous electrical nerve stimulator for pain relief. Electronic Code of Federal Regulations. https://www.ecfr.gov/current/title-21/section-882.5890
  2. Arik MI, Kiloatar H, Aslan B, Icelli M. The effect of TENS for pain relief in women with primary dysmenorrhea: A systematic review and meta-analysis. Explore. 2022. https://doi.org/10.1016/j.explore.2020.08.005
  3. Benduch M, Stania M. Is TENS an effective physical monotherapy for primary dysmenorrhea? A systematic review and meta-analysis. Pain Management. 2026. https://doi.org/10.1080/17581869.2025.2599728
  4. Ahmed MJ, Aldawsari WA, Aleid AM, et al. Transcutaneous electrical nerve stimulation for treatment of primary dysmenorrhea: A systematic review and meta-analysis of randomized controlled trials. Medicine. 2026. https://doi.org/10.1097/md.0000000000048007
  5. Han S, Park KS, Lee H, et al. Transcutaneous electrical nerve stimulation (TENS) for pain control in women with primary dysmenorrhoea. Cochrane Database of Systematic Reviews. 2024. https://doi.org/10.1002/14651858.cd013331.pub2
  6. Dowswell T, Bedwell C, Lavender T, Neilson JP. Transcutaneous electrical nerve stimulation (TENS) for pain relief in labour. Cochrane Database of Systematic Reviews. 2009. https://doi.org/10.1002/14651858.cd007214.pub2
  7. Thuvarakan K, Zimmermann H, Mikkelsen MK, Gazerani P. Transcutaneous Electrical Nerve Stimulation As A Pain-Relieving Approach in Labor Pain: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Neuromodulation. 2020. https://doi.org/10.1111/ner.13221
  8. Johnson MI, Paley CA, Jones G, Mulvey MR, Wittkopf PG. 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 (the meta-TENS study). BMJ Open. 2022. https://doi.org/10.1136/bmjopen-2021-051073
  9. Gibson W, Wand BM, Meads C, Catley MJ, O'Connell NE. Transcutaneous electrical nerve stimulation (TENS) for chronic pain: an overview of Cochrane Reviews. Cochrane Database of Systematic Reviews. 2019. https://doi.org/10.1002/14651858.cd011890.pub3
  10. Khadilkar A, Odebiyi DO, Brosseau L, Wells GA. Transcutaneous electrical nerve stimulation (TENS) versus placebo for chronic low-back pain. Cochrane Database of Systematic Reviews. 2008. https://doi.org/10.1002/14651858.cd003008.pub3
  11. Amer-Cuenca JJ, Lisón JF, Ferrer-Sargues FJ, et al. Dose-Response Effects of Transcutaneous Electrical Nerve Stimulation for Chronic Low Back Pain: A Systematic Review and Meta-Analysis. European Journal of Pain. 2026. https://doi.org/10.1002/ejp.70222
  12. Dailey DL, Vance CGT, Rakel BA, et al. Transcutaneous Electrical Nerve Stimulation Reduces Movement-Evoked Pain and Fatigue: A Randomized, Controlled Trial. Arthritis & Rheumatology. 2020. https://doi.org/10.1002/art.41170
  13. Dailey DL, Vance CGT, Van Gorp BJ, et al. Transcutaneous Electrical Nerve Stimulation and Pain With Movement in People With Fibromyalgia: A Cluster Randomized Clinical Trial. JAMA Network Open. 2026. https://doi.org/10.1001/jamanetworkopen.2026.2450
  14. Mira TAA, Yela DA, Podgaec S, Baracat EC, Benetti-Pinto CL. Hormonal treatment isolated versus hormonal treatment associated with electrotherapy for pelvic pain control in deep endometriosis: Randomized clinical trial. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2020. https://doi.org/10.1016/j.ejogrb.2020.10.018
  15. Li L, Moyer R, Stetter C, Riley K. A pre-post prospective study on the use of Transcutaneous Electrical Nerve Stimulation (TENS) unit in the management of endometriosis pain. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2026. https://doi.org/10.1016/j.ejogrb.2026.115042
  16. Johnson MI. Delayed adverse skin reaction to transcutaneous electrical nerve stimulation (TENS) electrodes. Pain Management. 2025. https://doi.org/10.1080/17581869.2025.2549238
  17. Li Y, Li C, Yang H, Zhang L, Xiong X. Assessing transcutaneous electrical nerve stimulation safety and adverse event reporting quality: A meta-epidemiologic study. Journal of Back and Musculoskeletal Rehabilitation. 2026. https://doi.org/10.1177/10538127261440640
  18. Chen D, Philip M, Philip PA, Monga TN. Cardiac pacemaker inhibition by transcutaneous electrical nerve stimulation. Archives of Physical Medicine and Rehabilitation. 1990. https://pubmed.ncbi.nlm.nih.gov/2136990/
  19. Mohammad S, Mayer C, Foisy M, et al. Inappropriate Implantable Cardioverter-Defibrillation Detection of Ventricular Fibrillation Induced by Transcutaneous Electrical Nerve Stimulation. Journal of Innovations in Cardiac Rhythm Management. 2022. https://doi.org/10.19102/icrm.2022.130506

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