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Advice on using a transcutaneous electrical nerve stimulation (TENS) machine

Patient information A-Z

This leaflet has been written to help you understand the TENS machine. We want you to feel confident about using the machine and we hope this leaflet answers most of your questions.

What is a TENS machine?

It is a small portable battery operated machine consisting of three major parts.

  1. Control box with battery
  2. Lead wires
  3. Electrodes (electric pads)

How does it work?

The TENS machine is thought to work by blocking the painful messages on their way to the brain. This happens in the spinal cord. It has also been found to increase the production of the body’s own natural painkillers, which are called endorphins.

Where should I place the electrodes?

The physiotherapist will show you where the electrodes can be placed on or around the pain. If this does not relieve your pain, the physiotherapist can show you how to place the electrodes on the nerves supplying the painful area.

Is there anywhere I should not place the electrodes?

The electrodes should not be placed on:

  • The front of the neck.
  • Over the spinal cord.
  • Near the eyes.
  • In the mouth or throat.

What will I feel?

The stimulation is felt as tingling impulses, which will get faster or slower when the frequency button is altered and stronger when the intensity is turned up. The frequency button should be set to the most comfortable position/mode (or as specified by your physiotherapist). The intensity should be turned up so that the sensation is strong but not unpleasant. When you get accustomed to the sensation, the intensity may need to be increased.

How often should I wear it?

Use the TENS for as long as you need to. You may find you are wearing the TENS for much of the day. Begin with short periods of 30 to 60 minutes. Increase as needed.

Will I be able to move about?

Yes, the TENS can be clipped on to a waistband or put in a pocket and should not interfere with your movement.

Should I still keep taking my pain killing tablets?

Yes, but if, after a few days the pain has been helped by the TENS you may need your tablets less frequently. You should discuss this with your GP/ consultant/ pharmacist.

Are there any precautions I should take?

  • Check that the skin under the electrodes is not getting sore. If redness develops, try moving the electrodes slightly each time you use TENS. If soreness continues, contact the physiotherapist who gave you the machine.
  • If you use the TENS for long periods of time, check twice a day that the gel on the pads has not dried out.
  • If you have any more concerns or queries, please contact your physiotherapist.
  • Near or over the heart.
  • Over an open wound.
  • The electrodes should be placed at least 1’’ (or 2cm) apart.
  • Areas of reduced sensation.

When is a TENS machine not suitable for use?

  • If you have a pacemaker fitted (fixed rate).
  • If you are pregnant (excluding labour).
  • If the skin is broken or fragile over the area you wish to place the electrodes.
  • Whilst driving or operating machinery.
  • If you suffer from epilepsy.
  • In the bath or shower.

Pain relief

To help us optimise your treatment, it is important that you have adequate pain relief. If you are suffering high levels of pain please seek advice from your pharmacist or GP.


Please contact our reception on 01223 216633 to leave a message for your physiotherapist, or to enquire about appointments.

This information has been compiled by the physiotherapy team at Addenbrooke’s Hospital. You may receive this information during an appointment with a physiotherapist, from your GP or via our outpatient physiotherapy page.

We are smoke-free

Smoking is not allowed anywhere on the hospital campus. For advice and support in quitting, contact your GP or the free NHS stop smoking helpline on 0800 169 0 169.

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Contact us

Cambridge University Hospitals
NHS Foundation Trust
Hills Road, Cambridge

Telephone +44 (0)1223 245151