Transcutaneous electrical nerve stimulation (TENS) is a method of pain relief that can help some people with long-term painful conditions.
A small, battery-operated machine is used to deliver electrical impulses into the body, which should feel like a pleasant tingling sensation. Leads are attached to the skin with reusable sticky plasters.
These impulses help block or reduce pain signals going to the spinal cord and brain, potentially reducing or relieving the pain or muscle spasms associated with a wide range of painful conditions. Low frequencies of electric current are also used to stimulate the body to release pain-relieving hormones called endorphins.
Does TENS work?
There is currently not enough scientific evidence to say for sure whether TENS is a reliable method of pain relief.
You can browse a list of [clinical trials currently investigating TENS].
Clinical experience has shown that it is effective for some patients, but this will depend on the condition and the patient. It is often used for patients who are unable to take pain medication because of unwanted side effects.
The amount of pain it can ease and the length of time it can last for also seem to vary from person to person. Generally, when the machine is on, it helps to relieve pain after about 40 minutes. Some people can get long-lasting pain relief once the machine is turned off, but this is not common.
Sometimes, TENS acts as a pleasant distraction from your pain.
If you're thinking about trying TENS, it should be tried alongside other treatments and lifestyle changes, such as pain mediction, exercise, relaxation and pacing your activities. Used alone, it is less likely to be effective.
TENS may be able to reduce pain and muscle spasms caused by a wide range of conditions, including:
Trying it out
If possible, it's a good idea to try TENS to see if it works for you before you go ahead and buy a machine.
First, check with your doctor that TENS is safe for you to use and see if they can refer you to a physiotherapist so you can try a TENS machine (however, this referral may not always be possible). Some online companies also offer a one-month trial, which can be useful.
If you find TENS effective, you can consider buying a TENS machine from a pharmacy. TENS machines range in price and vary in quality, so you may need to research the different brands. The more expensive machines are not necessarily any better than the lower-priced versions.
How to use TENS
The information below is a rough guide on how to use a TENS machine, but you should always follow the manufacturer's instructions.
A TENS machine can be used while you're working or on the move, as it is small and lightweight. You can put it in your pocket, clip it to your belt or hold it in the palm of your hand.
Leads from the machine (electrodes) are attached to your skin using self-adhesive pads. Position them either side of the area of most pain, no closer than an inch apart. Make sure the machine is switched off while you stick the electrodes to your skin.
Never place the electrodes over:
- the front or side of your neck (where there is a major artery)
- your temples
- your mouth or eyes
- your heart
- irritated or broken skin
- varicose veins
- numb areas
When you turn the machine on (do this slowly), a sensation will pass through to your skin, which you can control the strength of. Start off on a low setting and increase this gradually until you feel a tingling or buzzing sensation. If this sensation starts to become slightly uncomfortable or painful, reduce it slightly so it's at a level that feels effective but comfortable.
You may find that the sensation starts to reduce naturally after the initial tingling – this is your body becoming used to the effect. You can turn the current up slightly until the buzzing or tingling is there again. The sensation must always be strong but comfortable.
After you've finished using the TENS machine, switch it off. You can leave the electrodes on your skin until your next session, if this is more convenient.
You can use TENS throughout the day for at least three to four hours at a time (it takes about 45-60 minutes for TENS to produce pain relief). As long as you rotate the TENS plasters, you can have it on for more than 12 hours a day.
Risks and side effects
Providing your doctor or physiotherapist has confirmed that TENS is OK for you to use, it is a safe treatment with virtually no side effects. However, certain people cannot use TENS at all – see the box on this page.