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Use of TENS for pain relief


What is a TENS unit?

TENS stands for transcutaneous electrical nerve stimulation. Do not let the name scare you. An electronic TENS unit is simple to use and has worked well to control certain kinds of pain. Although it is not a cure, it is a routine part of pain management.

How does it work?

A TENS unit is a small, battery-operated device about the size of a beeper. It sends a small electric signal through self-stick pads that are placed in the painful area. The signal passes through the skin to the nerve fibers and stops pain signals before they reach the brain. If these signals do not reach the brain, then no pain is felt.

There are several theories about how a TENS unit works. The “gate control” theory suggests that TENS signals reach the pain centers in the brain before pain signals do. Like a busy signal on a telephone, the TENS closes the “gate” so that pain signals cannot get through. A second theory suggests that the short, mild electrical signals from the TENS unit cause the body to release its own pain relievers, called endorphins.

How do I use it?

A TENS unit is easy to use. Place the self-stick pads on either side of the painful area, turn the unit on, and turn the dial until you feel a tingling sensation. Then let the unit work for about 20 minutes.

What kind of pain can I treat with TENS?

TENS seems to work best for treating nerve pain. It also helps to ease pain after an operation. It tends to work better for pain that is located in a particular spot rather than in a wide area.

What does it feel like?

The feeling caused by TENS varies, but it is never uncomfortable. It usually feels like a light tingle or a gentle massage.

Is it safe?

TENS is safe and does not require a needle stick or any other treatment. It does not interfere with any medicine being taken. It can be used on any part of the body except over the heart, or in the front of the neck, or over the eyes. You should only use it as the doctor or therapist suggests.


Carbon-silicone with skin mounts

The electrodes most often used are made of a carbon-silicone material that comes in various shapes and sizes. These electrodes are used with “skin mounts” that hold the electrodes in place and help conduct the current.

  1. Clean and dry the black electrode.
  2. Peel the liner from one of the adhesive mounts.
  3. Carefully align the black electrode over the adhesive and press into place. There should be no large air bubbles trapped between the electrode and the adhesive.
  4. Insert the lead wire into the electrode and remove the clear liner from the adhesive. Keep the liner for storing the electrode when you aren't using it.
  5. Replace the adhesive mounting patches every 3 to 5 days. Pull off used adhesive before putting on new adhesive.

Reusable self-adhering

  1. Remove electrodes from foil pouch and reseal pouch to protect remaining electrodes. Keep the pouch for storing the electrodes.
  2. Attach lead wires to the electrodes before you remove the electrodes from the liner.
  3. Peel the liner from the electrode. Keep the liner for storage.
  4. You can remove and reattach this electrode for 7 to 10 days.
  5. Do not wear electrodes while showering, bathing, or swimming.
  6. Gently peel the electrodes from the skin at least once a day for cleaning.
  7. Add a few drops of water to the gel before you apply the electrode if the electrode gel seems to be dry.
  8. Replace the electrodes when you feel a change in stimulation or if the gel is crusted or separated.

Multi-day self-adhering

  1. Attach lead wires to the electrodes before you remove the electrodes from the paper liner.
  2. Peel the liner from the electrode.
  3. This electrode may stay in place for 2 to 5 days and can be worn while you are bathing or swimming.

Operating instructions

  1. Make sure the amplitude controls (2 knobs on top of the unit) are turned on all the way to the left to the “O” (off) position.
  2. Put a 9-volt battery into the battery compartment.
  3. Attach the electrodes to the lead wires.
  4. Prepare the electrodes for use according to the type of electrode you have been given and the instructions above.
  5. Use soap and water to clean the part of the body on which you will place the electrodes. Be sure to dry off completely. The unit will work best if the electrodes are placed on clean skin. Oils, creams, lotions, and soap residue can keep the unit from working well.
  6. Put the electrodes on your skin in the places that your therapist has shown you. Do not use the electrodes if your skin is broken or cut. Do not shave the area where the electrodes will be placed.
  7. Insert the plug ends of the lead wires into the output jacks of the TENS unit. You may put the lead wires into either jack.
  8. Turn the unit on by turning the amplitude control to the right until it clicks. Be sure you are turning the control nearest to the jack you have used. If you have used both jacks (4 electrodes) you will need to adjust both amplitude control knobs. The light (yellow or red) on the top of your unit will come on when the unit is on.
  9. Turn the amplitude control knob to the right until you feel a comfortable tingle. A sharp tingle that causes a feeling of pain will not be any more helpful, so do not turn the knob so far that the feeling is uncomfortable.
  10. Your therapist will have already set the mode, rate (hertz), and other knobs to the correct setting. Do not change these settings.
  11. After each use, turn the unit off by turning the amplitude control all the way to the left to the “O” (off) position.
  12. If the light does not come on when you turn your unit on, the battery needs to be changed. Always turn the unit off before you change batteries.
  13. A slide-on panel on the front covers the unit controls. Do not touch these controls. Do not remove the cover when you change the battery. Just press it slightly and slide it to the right.
  14. You can clip your TENS unit to your clothes.
  15. If your skin becomes red or sore, stop using the TENS unit, and call your doctor or therapist.

After treatment is completed

  1. Turn both amplitude control knobs to the “O” (off) position. Grasp the plugs, not the wires, and unplug the lead wires of the electrodes. You can leave the electrodes on your skin.
  2. After you remove the electrodes, clean your skin thoroughly with soap and water.


“On” indicator light is on, but unit does not work properly.

  • Check control settings. Have they been changed?
  • Are the electrodes in the proper place?
  • If reusable electrodes are used, try cleaning the electrode and replacing the gel. Too much or too little gel can cause problems.
  • Check the lead wires. Make sure all connectors are firmly seated.
  • Check for broken wire.

“On” and battery lights are dim.

  • Replace battery with a new one.

Indicator light is not on.

  • Replace battery with a new one.


If you have questions about using TENS for pain relief, call Rehabilitation Services at 595-3621. If you are inside the hospital, dial 3621. If you are outside the Memphis area, call toll-free 1-866-2ST-JUDE (1-866-278-5833), extension 3621.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).