TENS Machine For pain management


Nurse Director
Jun 8, 2007
The North
United Kingdom United Kingdom
TENS machines (Transcutaneous Electrical Nerve Stimulator)

How do TENS machines work?

Transcutaneous means 'through the skin'. TENS machines deliver small electrical pulses to the body via electrodes placed on the skin. TENS machines are thought to affect the way pain signals are sent to the brain. Pain signals reach the brain via nerves and the spinal cord. If pain signals can be blocked then the brain will receive fewer signals from the source of the pain. We may then feel less pain.

TENS machines are thought to work in two ways:

- When the machine is set on a high pulse rate (90-130 Hz) it is thought to trigger the 'pain gate' to close. The 'pain gate' is a theory that says that when certain non pain-carrying nerves are stimulated then these can can interfere with ('close') signals from nerves that transmit pain. The TENS machine is thought to stimulate certain non pain-carrying nerves. This may then interfere with or block pain messages sent to the brain. This is the normal method of use.
- When the machine is set on a low pulse rate (2-5 Hz) it stimulates the body to make its own pain easing chemicals called endorphins. These act a bit like morphine to block pain signals


Application of electrodes - best in 2 pairs placed diagonally to maximise the effect. Do not apply electrodes to:
  • Open wounds or rashes.
  • Swollen, red, infected, or inflamed skin.
  • Cancerous lesions, or close to them.
  • Skin that does not have normal sensation (feeling)
  • Any part of your head or face.
  • Any part of your throat.
  • Both sides of the chest or trunk at the same time.
  • Directly on your backbone
Most machines have a variety of modalities (effect) including tapping effect, buzzing, tingling and so on. First action is to find the effect that suits you. There may also be a setting where all or most of the effects are used in sequence. This works because when using one modality all the time, the nerves can become inured to it and lose effectiveness. Personally I prefer this 'all modes' setting. Make a note of the number and the strength that suits you.

Then you need to choose the strength setting. A middle setting is best to start with and increase or decrease to personal preference. It should be strong enough to feel but not so strong it's uncomfortable.

After a few minutes use, if you feel it reasonable, you could try turning up the volume a little but don't ever make it so strong it's uncomfortable or makes you jump!

After about 10-20 minutes, you might find the signal fades away and you may well be temped to turn it up a bit but DON'T do that. That's the point where the machine is working at peak effectiveness so leave it alone.

Usual recommended time for using a TENS is about 30 minutes but I have found I can use it a lot more than that. Provided the electrodes are securely in place, flat on your skin with no wrinkles or rucks and securely plugged into the leads, it should be perfectly safe to use it for longer periods. The machine shown has a 30 minute timer which means it switches off after that time. This is just a safety feature in case you fall asleep with it on - never a good idea!

In this 'diamond slot' formation,you get the signal crossing over that the centre point. It may not always be necessary and sometimes you might need to put one pair of electrodes on one spot and the other pair elsewhere. As you can see, this machine controls each pair (lead) separately which is good


January 22, 2017
Edited to include the following pluses and minuses

I am a big BIG fan of TENS machines. They give excellent pain management - when used correctly - and obviate the need to take medications. I see the +/- as:

1. TENS are safe and non-invasive and you're not taking any chemicals to achieve the end result
2. Time to effectiveness: TENS 0: Meds 15-20 minutes
3. Safe period of use: TENS limitless: usually every 4-6 hours
4. Side effects: TENS 0%: Med 90%!
5. Risk of dependence: TENS 0%: Meds significant

I've used TENS machines for years and am actually now on my fourth machine. I wore out or broke the others! They are relatively cheap and easy to get (in the UK, anyway, I usually get mine off Ebay - and the electrodes).
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