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How To Use A Tens Unit

What is it?

Transcutaneous (trans-q-tain-e-us) electrical nerve stimulation (stih-mew-la-shun) is a pain control treatment. It is often called TENS for short. A TENS unit is a portable, pocket-sized, battery-powered device. The TENS unit uses mild, safe electrical signals to help control pain.

When is TENS used to control pain?

A TENS unit treats many kinds of pain. It can help lessen acute (short-term) pain, like after surgery or an accident. Chronic (long-term) pain, like arthritis, back or muscle pain, or cancer pain may also be lessened with TENS. Some people have trouble taking pain medicine. TENS is a safe, drug-free way to help control pain for these people as well.

How does TENS work?

  • TENS lessens pain by sending painless electrical impulses through electrodes (sticky patches) placed on the skin. The electrical signals travel from the TENS unit through wires to the electrodes.

    • The signal then passes to the nerves under the skin. These nerves take messages to the brain about what they feel, such as touch, warmth, pressure, and pain. TENS signals can replace the message of pain on these nerves with a tingling sensation. This changes your impression of the pain.

    • The TENS signals may also increase the amount of endorphins (end-or-fins) in your body. Endorphins are a pain-relieving chemical made naturally by your body.

  • The electrodes are put in different places on your skin.

    • Where the electrodes are placed depends on the type and location of your pain. The electrodes may be placed to "cover" or "surround" the painful area. This works very well with muscle pain, spasms, or painful joints as in arthritis. Or, the electrodes may be placed to "capture" the pain as with the pain of a surgery incision (cut). The electrodes may be put between an injured nerve and the brain when a nerve has been hurt.

    • Putting the electrodes in the correct place is very important. If the electrodes are put in the wrong place your pain may not be lessened. The pain could even get worse if the electrodes are placed incorrectly. The electrodes should never be put near the eyes. The electrodes should also not be put over the nerves from the neck to the throat or brain.


Usually TENS treatment lasts 3 to 5 days. It may be used around the clock for some pain, like "phantom limb" pain. This is pain you feel in your foot or hand after that limb was amputated (cut off). Or, the TENS treatment may be used for 3 to 4 hours a day for pain like arthritis. You may be able to give yourself TENS treatments at home. If this is so, caregivers will teach you how to put on the electrodes and control the TENS unit.

  • Before the TENS treatment:

    • Test the battery pack of the TENS unit before starting to make sure it is fully charged. The TENS unit has 2 control knobs. One control knob makes the electrical signals strong or weak. The other control knob makes the electrical signal fast or slow. Turn the control knobs to " OFF " before starting.

    • Clean the skin where the electrodes will be placed with rubbing alcohol. Then dry the skin.

    • Put a thin coat of gel on the bottom of each electrode. This gel helps the electrical signal get to the nerves under the skin.

    • Put the electrodes on your skin and use tape or a sticky patch to cover the electrode. This keeps the electrode firmly stuck to the skin. Have a family member help if you cannot reach the area where the electrodes are to be placed.

    • Hook the pin connectors on the end of the electrode wires unto the electrodes. The electrode wires are then plugged into the TENS unit.

    • The control knobs are slowly turned to the correct setting. You should feel a tingling feeling. Talk to your caregiver about what settings may be best for you.

    • The TENS unit is then hooked to your belt or placed in a pocket.

  • During the TENS treatment:

    • Tell caregivers if your muscles start to twitch. This may mean that the TENS signals are too strong or too fast. Also tell caregivers if you cannot feel any tingling at all. This may mean that the signal is too weak or too slow.

    • The electrodes should be removed at least once a day if the TENS treatment is used around the clock. The skin under the electrodes is checked to see if it is red or tender. The skin should also be cleaned and dried while the electrodes are off. Put lotion on your skin where the electrodes were placed. The electrodes should be put in a new place for each new treatment. This will help prevent the skin from becoming red or sore. New gel is put on the bottom of the electrode before putting it back on the skin.

    • Do not get into water or sleep with the electrodes on your skin and the TENS unit turned on.

  • After the TENS treatment:

    • Turn the control knobs to "OFF". Unplug the electrode wires from the TENS unit.

    • The electrodes may be left on your skin if you will have another TENS treatment soon. If not, remove the electrodes. Wash the skin where the electrodes were placed. Clean the electrodes with soap and water to remove the gel. Do not use alcohol because this can damage the rubber on the electrode. Get new electrodes if the electrodes become damaged or will not stay stuck to the skin.

    • Remove the battery from the TENS and replace it with a charged battery. The used battery is recharged so that it will be ready for another treatment.


TENS should not be used for people who have a heart pacemaker. The signals from the TENS unit could interfere with how the pacemaker works. Care should be taken when using TENS if you have any heart problems. Pregnant women should not use TENS. It is not yet known how TENS may effect an unborn baby. Do not put the TENS electrodes on your head or neck if you have problems with your blood or blood vessels. Also, do not put the electrodes on your head or neck if you have seizures (convulsions).

Care Agreement

You have the right to help plan your care. To help with this plan, you must learn about pain and how it can be treated. You can then discuss treatment options with your caregivers. Work with them to decide what care will be used to treat you. You always have the right to refuse treatment.The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

© 2014 Truven Health Analytics Inc. Information is for End User's use only and may not be sold, redistributed or otherwise used for commercial purposes. All illustrations and images included in CareNotes® are the copyrighted property of A.D.A.M., Inc. or Truven Health Analytics.