TENS Unit: How It Works, Uses & Safety

Jillian Kinton-Vieira
Created by: Jillian Kinton-Vieira Registered Nurse
Key points
  • A TENS unit delivers mild electrical impulses through the skin to help manage certain types of acute or chronic pain.
  • Portable TENS units may be used at home, but electrode placement, intensity, and session length should follow professional guidance.
  • TENS should not be used over broken or numb skin or without medical approval during pregnancy or with certain implanted electronic devices.

A TENS unit, or transcutaneous electrical nerve stimulation unit, is a medical device that delivers mild electrical impulses through electrodes placed on the skin. It may help manage lower back pain, sciatica, tendinitis pain, and other types of acute or chronic pain.

Transcutaneous electrical nerve stimulation works by stimulating sensory nerves and altering how pain signals are transmitted or perceived. It may also activate the body’s natural pain-control mechanisms, including the release of endorphins and enkephalins, which have pain-relieving effects.

TENS therapy may be administered by a physical therapist using electrical pulse settings selected for the condition being treated. Portable TENS units may also be used at home, preferably with initial guidance from a healthcare professional.

practitioner placing TENS device on patient's back

How a TENS unit works

Transcutaneous electrical nerve stimulation (TENS), is used to help relieve pain by stimulating sensory nerves.

This stimulation may produce a pain-relieving effect by activating the body’s natural pain-control mechanisms, including nerve fibers involved in regulating pain and the release of endorphins.

Some electrical stimulation settings may also stimulate muscles and increase local blood flow. However, TENS is mainly used for temporary or symptomatic pain relief and has not been proven to directly heal soft-tissue injuries.

What TENS is used for

TENS may be recommended for:

TENS may also be considered for certain types of chronic pain or pain following surgery or injury. According to the US Food and Drug Administration, the intended uses of a TENS unit depend on the specific device, and FDA-cleared models may be indicated for temporary relief of sore or aching muscles or for the symptomatic management of certain types of chronic pain.

Can TENS relieve labor pain?

TENS may be used as a nonmedication option to help manage labor pain, particularly lower back pain. However, its effectiveness may vary, and it should not replace other pain-relief options when they are needed.

During labor, TENS should only be used with the approval and supervision of the obstetric care team. The electrodes are generally placed on the back and should not be placed over the abdomen or pelvis.

What to expect

TENS may be administered by a physical therapist in a clinic or used at home, depending on the device and treatment plan. The length of each session varies based on the condition being treated, the device settings, the manufacturer’s instructions, and the individual response.

TENS is generally used as follows:

  • Place the electrodes on clean, dry, intact skin near the area being treated

  • Connect the lead wires to the device and electrodes, if required

  • Turn on the TENS unit

  • Slowly increase the intensity until a strong but comfortable tingling sensation is felt

  • Continue the stimulation for the recommended amount of time

  • Turn off the TENS unit when the session is complete

  • Disconnect the lead wires, if applicable

  • Remove the electrodes from the skin

TENS is a noninvasive treatment and is not associated with physical dependence. It is generally well tolerated, although skin irritation, redness, discomfort, or unpleasant stimulation may occur.

The device should be turned off and medical advice sought if the stimulation becomes painful or causes a burn or persistent skin reaction.

Portable TENS unit

A portable TENS unit is a small, battery-powered device that delivers electrical impulses through electrodes placed on the skin. Depending on the model, the electrodes may be connected by lead wires or incorporated into a wireless device.

Portable TENS units may have different stimulation modes and intensity settings. Some models are intended for home use.

Before using a TENS unit, it is important to follow the manufacturer’s instructions for electrode placement, session length, and intensity. The stimulation should feel strong but comfortable and should not be painful.

Main types

The main types of TENS include:

1. Conventional TENS

Conventional TENS uses low-intensity electrical pulses with a short pulse duration and a relatively high frequency, such as 50 to 100 Hz.

This type of TENS stimulates sensory nerves and may reduce the transmission or perception of pain signals. It may be used as part of the management of acute or chronic pain.

2. Burst TENS

Burst TENS delivers groups of high-frequency electrical pulses at a lower burst rate. The intensity may be high enough to produce mild muscle contractions.

This type of TENS may stimulate sensory and motor nerves and may provide pain relief that continues for a period after treatment. The appropriate duration and intensity should be determined by a healthcare professional.

3. Brief intense TENS

Brief intense TENS uses high-frequency, high-intensity electrical pulses for short periods. It may cause an intense or mildly uncomfortable sensation and is generally administered under professional supervision.

This type of TENS may be used immediately before or during short, painful procedures, such as wound care, dressing changes, or suture removal.

Contraindications for use

TENS should not be used, or should only be used with medical approval, in the following situations:

  • An implanted pacemaker, defibrillator, or other electronic medical device

  • Certain heart rhythm disorders

  • Known or suspected deep vein thrombosis (DVT) in the treatment area

  • Epilepsy, particularly when electrodes would be placed on the head or neck

  • Broken, infected, inflamed, or irritated skin

  • Areas with reduced or absent sensation

  • Areas affected by active bleeding or cancer, unless specifically approved by the treating medical team

  • Pregnancy, unless approved by the obstetric care team

Electrodes should not be placed over the eyes, mouth, front or sides of the neck, or head. They should also not be positioned on the chest in a way that allows electrical current to pass across the heart or placed directly over broken or numb skin.

During pregnancy, a TENS unit should only be used with the approval of the obstetric care team. Electrodes should not be placed over the abdomen, pelvis, or lower back unless specifically recommended and supervised by a healthcare professional.

Update History
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References
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