New 2026 research on TENS for endometriosis: what the study shows — and doesn't

If you live with endometriosis or regular period cramps, you've probably already worked out that the painkillers prescribed to you don't always do the job. Transcutaneous Electrical Nerve Stimulation (TENS) — the mechanism behind consumer period-pain devices like Livia, Ovira, and Myoovi — has become a popular drug-free alternative.

TENS has reasonable evidence for straightforward period cramps. New 2026 research just tested it directly for endometriosis pain, and the answer is more complicated.

What the new study did

Researchers at Penn State recruited women with surgically confirmed endometriosis, 27 of whom completed the full protocol (79.4% completion from the 34 who received the intervention). Each participant completed a 3-month baseline period, then a 3-month phase in which they used a small TENS unit during pain flares — as often and for as long as they wanted. The team measured pain (Visual Analogue Score, VAS), quality of life (Endometriosis Health Profile, EHP-30), sexual function (Female Sexual Function Index, FSFI), and over-the-counter painkiller use across both phases.

There was no control group, no sham device, and no blinding. This is a pre-post study, not a randomized trial. One participant withdrew because of skin irritation from the TENS adhesive pads.

What they found

The study's primary outcome was pain on the VAS — and it was the outcome that didn't move:

• Pain (VAS) dropped by 2.29 points — not statistically significant (p = 0.44).

Two secondary outcomes did move:

• Quality of life improved by 16.57 points on the EHP-30 (p < 0.001).
• Ibuprofen use dropped by 93 mg per day (p = 0.02).

Other secondary outcomes — FSFI and acetaminophen use — trended in the expected direction but didn't reach significance.

Read carefully: the outcome the study was set up to measure didn't reliably change. The pattern of everything else did.

Why does TENS help period cramps but not endometriosis pain?

This isn't a confusing result — it's consistent with what we know about both TENS and endometriosis pain.

TENS works via the peripheral pain gate: fast sensory fibers crowd out the pain-carrying ones at the level of the spinal cord. For acute, localized pain, that can help — which is why consumer TENS devices have real randomized-trial evidence for primary dysmenorrhea, i.e. period cramps without an underlying condition. For that type of pain, the mechanism matches the problem.

Endometriosis pain is different. It's still partly peripheral and inflammatory, but it also involves the central nervous system itself. Long-standing pelvic pain drives central sensitization: the brain and spinal cord rewire how they process pain signals, which is part of why so many people with endometriosis continue to experience pain even after lesion removal or hormonal treatment.

TENS doesn't reach that central piece. So finding that TENS didn't meaningfully reduce pain scores in the endometriosis study isn't a failure of the device — it's what you'd expect, given the mechanism.

The quality-of-life and medication-use changes are a separate question. Without a sham or control arm, the study can't cleanly separate real benefit from placebo, regression to the mean, or the simple fact that having something you can do during a flare is better than having nothing.

What this actually tells us

Read honestly, this paper is less about TENS and more about behavior: women with endometriosis want tools they can use themselves, at home, during flares — and using one meaningfully changes how they feel about living with the condition, even when the pain score doesn't move.

That's a real signal about what people want. It isn't a strong efficacy result for endometriosis-related pain.

Where the stronger evidence for at-home endometriosis pain relief sits

For endometriosis-related pain specifically, the stronger evidence sits with neuromodulation that targets central processing rather than peripheral signaling.

Mechsner et al. (2023), published in Pain Medicine, ran a placebo-controlled randomized controlled trial (RCT) in 36 people with chronic pelvic pain associated with endometriosis. Non-invasive brain stimulation significantly reduced pain scores and pressure pain thresholds, and the effect persisted one week after stimulation ended — not something you'd expect from a peripheral-only device.

Samphire's own Nettle™ trial reported a 53% reduction in pain across a single menstrual cycle.

Building on those foundations, Samphire is currently collaborating with NHS trusts to run the first clinical trials of accessible, at-home neurotechnology — specifically the brain-based devices Nettle™ and Lutea™ — for endometriosis pain. The aim is to build the kind of randomized, controlled evidence base the category has been missing, and to establish what brain-targeted stimulation can deliver for a condition the peripheral mechanism doesn't reach.

Neither existing research replaces surgical or medical management of endometriosis. But if you're looking for an at-home, non-pharmacological option with real evidence behind it, the research points more clearly toward brain-based neuromodulation than toward TENS for endometriosis specifically.

Bottom line

The new 2026 TENS paper is a useful data point about what women with endometriosis are looking for. It isn't a strong argument that TENS itself addresses endometriosis pain — even though TENS has real evidence for ordinary period cramps. For endometriosis pain, the more persuasive research to date is about the central nervous system, not the peripheral one — and that's the ground Samphire's own NHS trial work is built on.

Frequently asked questions

Does TENS work for period pain?

There is reasonable randomized-trial evidence that TENS can reduce pain from primary dysmenorrhea — period cramps without an underlying condition. That's partly why consumer period-pain devices like Livia, Ovira, and Myoovi have a loyal following.

Does TENS work for endometriosis pain?

In the new 2026 Penn State study, TENS did not significantly reduce pain scores on the VAS — the trial's primary pain outcome was null (−2.29 points, p = 0.44). Quality of life and ibuprofen use did improve, but without a control arm those changes can't be cleanly attributed to the device.

Is endometriosis pain the same as regular period pain?

No. Period cramps without an underlying condition (primary dysmenorrhea) are mostly peripheral and inflammatory. Endometriosis pain involves the same pathways plus neuropathic and centrally sensitized components — which is part of why treatments that help period cramps don't always help endometriosis.

What do these results mean for Livia, Ovira, or Myoovi?

Livia, Ovira, Myoovi, and similar consumer devices all rely on the same underlying TENS mechanism — peripheral nerve stimulation via the pain gate. They have a reasonable evidence base for period cramps. The 2026 study used a generic TENS unit, but its findings are about what TENS as a mechanism can and can't do for endometriosis pain. The evidence gap it surfaces applies to the category, not to any one brand.

What research is Samphire doing on endometriosis pain?

Samphire is collaborating with NHS trusts to run the first clinical trials of accessible at-home neurotechnology — specifically the brain-based devices Nettle™ and Lutea™ — for endometriosis pain. The goal is to build a rigorous, randomized evidence base for at-home, non-pharmacological options that target the central nervous system rather than only the periphery.

Is TENS a proven treatment for endometriosis?

No. Current evidence for TENS in endometriosis is pre-post and uncontrolled, not randomized. TENS targets peripheral pain signaling, which likely doesn't reach the central and neuropathic components that drive much of endometriosis pain.

What are better-evidenced at-home options for endometriosis and chronic pelvic pain?

Non-invasive brain stimulation has stronger evidence. Mechsner et al. (2023) in Pain Medicine reported a placebo-controlled RCT in 36 people with chronic pelvic pain linked to endometriosis, with significant pain reduction and effects lasting up to one week after stimulation ended.

How was the 2026 TENS study designed?

A pre-post prospective study at Penn State. 27 women with surgically confirmed endometriosis completed a 3-month baseline followed by a 3-month self-directed TENS phase. The team measured pain (VAS), quality of life (EHP-30), sexual function (FSFI), and over-the-counter painkiller use.

Is there a risk to using TENS units?

TENS is generally low-risk for short-term use. In this study, one participant withdrew due to skin irritation from the adhesive pads.