Transcutaneous Electrical Nerve Stimulation (TENS)


What is TENS?

  • TENS is the most common and accessible form of hyper stimulation analgesia.
  • It is a noninvasive, non-addictive technique useful in both acute and chronic pain and in both pathophysiological and neuropathic pain.
  • It can be used for peripheral nerve disorders, phantom limb pain, spinal cord and spinal root lesions, low back pain, period pain, and muscle and joint pain.
  • It does not cure the underlying cause of the pain.
  • It can be very effective in relieving pain and, unlike pain medication, it does not cause nausea, drowsiness, personality changes, dependence, or limit daily activities.
  • It can help to decrease the reliance on oral analgesics.


How Does TENS Work?

  • It stimulates nerve fibres, diminishing transmission of the fibres that produce pain. 
  • This means that the electrical current blocks the pain signal to the brain.
  • Another theory is that the electrical activity may cause the body to release its own pain analgesics; these are called beta endorphins, which is in line with the gate theory.
  • The machine runs on a 9 volt battery so there is no risk at any time of electrocution.


What Does a TENS Machine Look Like?

  • The machine itself is typically the size of a large pager.
  • There are two leads. Some machines will only have one, but most are equipped with two outlet ports.
  • Pads are connected to the leads, which in turn are connected to the TENS machine.
  • On the top of the machine are two on/off dials, one for each lead.
    • A light will become visible when these are turned on.
    • They have a range from 0 to 8.
  • Inside the cover you will see a selection of dials. Each are labeled.
  • There is a timer with a switch with 30/C/60 written underneath it.
    • The 30 and 60 refer to a timer, whereby it will switch off after either 30 or 60 minutes. This can be especially helpful when getting off to sleep.
    • The C refers to continuous, whereby there will be a continual current.
  • There is another switch which has the letters B/N/M written underneath it.
    • The N refers to Normal Mode whereby there is a steady stream of pulses.
    • The B refers to Burst Mode whereby each second there will be two bursts of pulses.
    • The M refers to Modulation Mode, which is a slower 4 second cycle.
  • The two dials refer to Pulse Width and Pulse Frequency.?
    • Pulse Width - This dial regulates the width or duration of each pulse, between 60 – 250 microseconds.
      • The wider the pulse, the slower it will be.
    • Pulse Frequency - This dial regulates the number of pulses per second, between 2 – 150 pulses per second.


Important Information Regarding Using a TENS Machine

  • It is important the TENS machine is not used for new pain. If you experience new pain it is imperative that you are assessed first, prior to using the TENS.
  • A nurse from Hunter Pain Clinic will provide a body diagram showing where the pads are to be placed to give optimal cover of your pain.
  • The TENS pads must NEVER be placed on your face, over your eyes, or over your carotid arteries (which are located on the front of your neck).
  • The settings can be changed to suit your personal requirements. It is important to experiment with the settings to find what best suits your needs. What suits one person may not suite you.
  • Do not use the TENS while you are driving, or operating machinery. If you find that this is a necessary part of your work, do not change the position of the controls while you are working. 


Using a TENS Machine

  • Ensure the TENS machine is turned off at the dials before applying or removing the electrodes.
  • Place the pads on, and connect them to the machine. If your pain is low back pain, you may require some assistance in getting the pads in the correct position.
  • Turn the on/off dial on slowly until you begin to feel a tingling sensation.
  • It is recommended that you start slowly, beginning at an hour per day, increasing use up to 6 hours per day as the need arises.
  • Once you feel a steady tingling sensation, experiment with the settings until you find what is comfortable for you.
  • You may find that one setting works best while you are active, and another setting is best for when you are going to sleep.


Using the Electrodes

  • The skin must be clean, dry and free from lotion or hair.
  • Always lift the electrodes from the edge, not the lead wire.
  • Always replace the electrodes to the “on” side of the storage liner.
  • Always store and seal the electrodes in the original package in a cool, dry place.
  • Never submerge electrodes or get them wet.
  • Rehydrate the gel with a drop of water.
  • Using heat or cold packs for long periods of time can cause adhesive separation.
  • Electrodes are for single patient use only. Do not share your electrodes.



  • Do not use a TENS machine if you:
    • Have a pacemaker.
    • Have a heart problem or a history of cardiac disease.
    • Are pregnant. There are no studies that either support or deny use of a TENS machine during pregnancy.


If you require further information, or are unsure at any time how to use your TENS machine, please contact the Nurses at the Hunter Pain Clinic on (02) 4985 1800.


* Image 1 by Yeza (Own work) [GFDL ( or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (], via Wikimedia Commons
* Image 2 by Thomas671973 (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons