TENS Unit: How Transcutaneous Electrical Nerve Stimulation Relieves Pain
Updated: 6 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026 · How we review
Quick Answer: What is TENS?
Transcutaneous electrical nerve stimulation (TENS) is a noninvasive pain relief therapy that sends a low-voltage electrical current through pads on the skin to block pain signals or boost the body's natural painkillers. It is used for back pain, osteoarthritis, fibromyalgia and nerve pain, and it is not safe for people with pacemakers, epilepsy or pregnancy. [1] [2]
What the research says
TENS lowers pain more than a placebo device. A review of 381 randomized trials (24,532 people) found pain was clearly lower during or right after TENS than with placebo (91 trials, 4,841 people; moderate-certainty evidence), and side effects were mild and no more common than with comparison treatments. (Johnson et al., BMJ Open, 2022) [2]
In knee osteoarthritis, TENS eased pain and improved walking. A meta-analysis of randomized trials found active TENS reduced pain more than sham TENS and improved function and walking ability, but it did not help joint stiffness. (Wu et al., Clinical Rehabilitation, 2022) [3]
For chronic low back pain, the benefit was small. A review of 17 trials (1,027 adults) found only a brief, marginal pain drop versus sham at 2 weeks (−0.90 points), judged too small to matter clinically, with very low-certainty evidence. (Verville et al., Journal of Occupational Rehabilitation, 2023) [4]
Key takeaways
TENS uses a mild electrical current to block pain or change how you feel it. [1]
It treats both short-term and long-term pain, from tendinitis to diabetes-related nerve pain. [1]
Most people feel relief right away, and it usually fades within an hour of stopping. [1]
It is generally safe, but some people must avoid it completely. [1]
Talk to your healthcare provider before buying or using a TENS unit. [1]
What is a TENS unit and what does it do?
A TENS unit is a small, battery-powered device that sends electrical impulses through your skin using sticky electrode pads. [1] It is about the size of a small cell phone. [1]
The pads go at or near trigger points (muscle knots) or the nerves that carry pain from the affected area. [1]
You can get TENS in three ways: [1]
Where you get TENS | What it means |
In a clinic or hospital | A healthcare provider applies TENS during your visit |
By prescription | Your provider prescribes a unit for home use |
Over the counter | You buy a unit at a pharmacy without a prescription |
Many TENS units have FDA approval, but the right device depends on your needs. [1] Your provider can also show you how and where to place the pads. [1]
How does TENS work to relieve pain?
TENS relieves pain in one of two ways, according to the two leading theories. [1]
TENS works well for many people, and better for some than for others. [1] Researchers still do not know exactly why, but most experts believe the current helps release the body's own pain-reducing chemicals. [1]
What conditions does TENS treat?
TENS treats a wide range of acute (short-term) and chronic (long-term) pain conditions. [1]
Condition | Type of pain | Learn more |
Back pain | Muscle and spine pain | |
Osteoarthritis | Joint pain | |
Fibromyalgia | Widespread body pain | — |
Tendinitis | Tendon pain | |
Bursitis | Joint cushion (bursa) pain | — |
Chronic pelvic pain | Long-term pelvic pain | |
Diabetes-related neuropathy | Nerve pain | |
Peripheral artery disease (PAD) | Leg pain from poor blood flow |
For nerve pain in general, see our peripheral neuropathy guide.
How do you use a TENS unit?
You use a TENS unit by sticking its pads on your skin over the painful area and adjusting the pulses until they feel strong but comfortable. [1]
Each kit comes with several sets of electrodes, wires and pads. [1] Here is how a session works: [1]
Connect the wires. Each electrode connects to the unit at one end and to a 2-inch by 2-inch pad at the other.
Place the pads. The adhesive backing sticks to your skin. You or your provider position the pads along nerve pathways in the affected area.
Turn it on. The unit delivers pulses of electrical energy.
Adjust the settings. Change the intensity, frequency and duration until the impulses feel strong but comfortable.
Setting | What it controls |
Intensity | How strong each pulse feels |
Frequency | How often the pulses come |
Duration | How long each pulse lasts |
How often and how long can you use a TENS unit?
You can generally use a TENS unit as often as you want. [1] Some people use it several times a day, for up to 60 minutes each time. [1] Check with your healthcare provider before you start. [1]
How long does TENS pain relief last?
TENS pain relief usually starts right after the session begins and stops within one hour of finishing it. [1]
How long relief lasts varies from person to person. [1] Some people say they feel better for up to 24 hours after a session, while others notice their pain returns as soon as they switch the unit off. [1]
Who should not use a TENS unit?
You should not use a TENS unit if you are pregnant or have certain health conditions. [1]
Avoid TENS if you: [1]
Are pregnant
Have a pacemaker or other implanted device
Have cancer
Have epilepsy
Have a bleeding disorder
Have heart disease
Always check with your healthcare provider before using TENS, especially if you have an existing health condition. [1]
Where should you never place TENS pads?
TENS pads should never go on or near sensitive, damaged or numb areas of the body. Never place pads across your chest, because the current can affect your heart rhythm, and do not use TENS while driving, bathing or sleeping. [1] Avoid placing them on or near: [1]
Eyes, mouth or head
Front or side of the neck
Genitals
Infected tissue or damaged skin
Varicose veins
Areas of numbness
Areas that recently received radiation therapy
What are the benefits and side effects of TENS?
The main benefits of TENS are that it is noninvasive, portable and relieves pain for many people. [1]
Benefits | Possible side effects |
Noninvasive | Allergic reaction to the pad adhesive |
Works alone or alongside pain relievers | Uncomfortable prickling or tingling feeling |
May lower medication doses in some people | Burns from the electrodes (rare) |
Small and portable | — |
Effectively relieves pain for many people | — |
Never change your medication dose on your own. [1] Talk to your healthcare provider first.
When should you call your doctor about TENS side effects?
You should call your healthcare provider if you develop any new symptoms while using TENS. [1] Watch for: [1]
Skin rash
Itchy skin (pruritus)
Dizziness
Headaches
Nausea
Does TENS really work for pain?
TENS relieves pain for many people, but how well it works depends on the person and how it is used. [1] Some studies show strong relief, while others suggest a placebo works just as well. [1]
Success likely depends on several factors: [1]
Whether you have an underlying condition
Where the electrodes are placed
Which TENS unit settings you use
The largest review to date found pain was lower with TENS than with placebo, without serious side effects. [2] Results differ by condition: benefits were clear in knee osteoarthritis [3] but small in chronic low back pain. [4] For more background, see this overview of TENS.
TENS at a glance
Question | Answer |
What it is | Noninvasive pain relief using a low-voltage electrical current |
Device size | About the size of a small cell phone |
Pad size | 2 inches by 2 inches |
Session length | Up to 60 minutes, several times a day |
When relief starts | Right after the session begins |
How long relief lasts | Usually stops within an hour; some report up to 24 hours |
Main side effects | Adhesive allergy, tingling discomfort, rare burns |
Who should avoid it | Pregnancy, pacemaker, cancer, epilepsy, DVT, bleeding disorders, heart disease |
Conclusion
TENS is a simple, noninvasive way to ease short-term and long-term pain, and it works well for many people. [1] Science is still learning exactly how it works, but if you live with ongoing pain, it is likely worth a try with your provider's guidance. [1] Place the pads correctly, keep the pulses strong but comfortable, and stop if you notice a rash, dizziness or other new symptoms.
Living with pain? Explore our back pain, knee pain and peripheral neuropathy guides to understand your options, and follow us on Instagram and YouTube for clear, research-backed health updates every week. Then bring your questions to your healthcare provider before your first TENS session.
FAQ
What is a TENS unit used for?
A TENS unit is used to relieve acute and chronic pain with a mild electrical current. Common uses include back pain, osteoarthritis, fibromyalgia, tendinitis, bursitis, chronic pelvic pain, diabetes-related neuropathy and peripheral artery disease. [1]
How does a TENS unit work?
A TENS unit works by sending electrical pulses through skin pads to nearby nerves. The current may block pain signals or raise endorphins, the body's natural painkillers. [1]
How often can you use a TENS unit?
You can generally use a TENS unit as often as you want. Some people use it several times a day for up to 60 minutes each time, but check with your healthcare provider first. [1]
How long does TENS pain relief last?
TENS pain relief usually starts right away and stops within one hour after the session ends. Some people report feeling better for up to 24 hours, while others feel pain return as soon as the unit is off. [1]
Who should not use a TENS unit?
People who are pregnant should not use a TENS unit. It should also be avoided by people with a pacemaker or other implanted device, cancer, epilepsy, deep vein thrombosis, bleeding disorders or heart disease. [1]
Where should you not put TENS pads?
TENS pads should not go on the eyes, mouth, head, front or side of the neck, or genitals. Also avoid infected or damaged skin, varicose veins, numb areas and areas recently treated with radiation. [1]
What are the side effects of a TENS unit?
The side effects of a TENS unit include allergic reactions to the pad adhesive and an uncomfortable prickling or tingling feeling. Burns from the electrodes can happen but are rare. [1]
Does TENS really work?
TENS relieves pain for many people, and a review of 381 trials found it lowered pain more than placebo. Results vary by condition, electrode placement and settings. [2]
Do you need a prescription for a TENS unit?
Many TENS units are sold over the counter, though some models need a prescription. A doctor or physical therapist can help you choose safe settings and pad placement for your condition.
Can you use a TENS unit while sleeping?
No. Do not use a TENS unit while sleeping, because you cannot notice skin irritation or discomfort. Turn the unit off and remove the pads before bed.
Related Reading
PEMF Therapy: What Pulsed Electromagnetic Field Therapy Does explains PEMF therapy and what research shows.
Pain Management: Types, Treatments and What to Expect explains the treatment options for acute and chronic pain.
References
Cleveland Clinic. Transcutaneous Electrical Nerve Stimulation (TENS). Cleveland Clinic. Last updated September 25, 2023. https://my.clevelandclinic.org/health/treatments/15840-transcutaneous-electrical-nerve-stimulation-tens
Johnson MI, Paley CA, Jones G, et al. 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;12(2):e051073. PMID 35144946. https://doi.org/10.1136/bmjopen-2021-051073
Wu Y, Zhu F, Chen W, et al. Effects of transcutaneous electrical nerve stimulation (TENS) in people with knee osteoarthritis: A systematic review and meta-analysis. Clin Rehabil. 2022;36(4):472-485. PMID 34971318. https://doi.org/10.1177/02692155211065636
Verville L, Hincapié CA, Southerst D, et al. Systematic Review to Inform a World Health Organization (WHO) Clinical Practice Guideline: Benefits and Harms of Transcutaneous Electrical Nerve Stimulation (TENS) for Chronic Primary Low Back Pain in Adults. J Occup Rehabil. 2023;33(4):651-660. PMID 37991646. https://doi.org/10.1007/s10926-023-10121-7
Medical disclaimer
This article is for general education only and does not replace professional medical advice, diagnosis or treatment. Always talk to a qualified healthcare provider before starting TENS or any new pain treatment, especially if you are pregnant or have a medical condition or implanted device.
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