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What is TENS, and How Does it Work?


Updated June 09, 2014

Chiropractor Performing a Median NCV (Nerve Conduction Velocity)
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What TENS Is:

TENS stands for transcutaneous electrical nerve stimulation, which sounds much scarier than it actually is. With TENS, sticky electrodes are placed on the skin around the painful area. When the TENS unit is turned on, it delivers a light current through the electrodes to the skin and tissues just beneath it. Using TENS feels a bit like tingling, or pins and needles, though the intensity can be set high enough to make a muscle twitch.

How TENS Works:

TENS is thought to disrupt the pain cycle by delivering a different, non-painful sensation to the skin aroudn the pain site. In essence, it modulates the way we process the pain sensations from that area. TENS closes the pain gate, so to speak.

Depending on the frequency the TENS unit delivers, the electrical stimulation can also trigger the body to release endorphins. Endorphins act as natural painkillers, and help promote a feeling of well-being.

TENS for Chronic Pain:

Does TENS relieve chronic pain? Sadly, the jury is still out on this one. A number of researchers have determined that TENS can help control chronic pain. However most studies show little difference between the TENS unit and the placebo. Like most chronic pain treatments, it does not work for everyone.

The good news is that TENS has few side effects, if any. It won't interact with your other medications, and it won't make you drowsy. Once your TENS unit is programmed, it is easy to apply, and can be worn during most activities.

The Downside of TENS:

TENS can lure you into a false sense of security, especially the first few times you use it. Many people feel pain relief and over-exert themselves, making their pain even worse. It has been my experience that people either love TENS, or they hate it. There is little gray area with these devices.

A few minor risks are associated with TENS. For instance, it should not be used if you have poor sensation, if you are pregnant, if you have cancer or if you have a pacemaker. It should never be used around the heart, on the head or over breast tissue. There is also a minor risk of skin irritation, but this is rare.

Trying TENS:

Though you can purchase a TENS unit online, you should first consult your doctor about using one. Your doctor can refer you to a physical therapist who can help you determine the most appropriate setting for your TENS unit. You may need to try a few settings before you find the one that works best for you.


Chesterton, Linda at al. Effects of TENS frequency, intensity and stimulation site parameter manipulation on pressure pain thresholds in healthy human subjects. Pain. Volume 106, Issues 1-2. November 2003, pp 73-80.

Oosterhof, Jan et al. Predicting outcome of TENS in chronic pain: A prospective, randomized, placebo controlled trial. Pain. Volume 136, Issues 1-2. May 2008, pp 11-20.

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