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TENS Machine: This is Everything You Need to Know

April 13, 2017 in TENS Therapy


What is a TENS Machine?

Transcutaneous electrical nerve stimulation (TENS) is a form of therapy that uses a low-voltage electrical current to relieve pain. TENS machines are safe and have been used by doctors and physical therapists for decades.

Modern TENS machines can be as small as a smartphone and powered by batteries. The device is connected to wires that conduct an electrical current through self-sticking massage pads. These pads are placed on an area of pain, and a circuit of electrical impulses travel along the nerve fibres. TENS machines have different intensities, which means you can adjust the flow of the electrical current. TENS is primarily used for pain relief. 1

Click here to learn how to use a TENS machine.

How Do TENS Machines Work?

TENS machines override pain receptors in the brain. A comparable way to look at this concept is by looking at phone signals. When a cell phone dials a number, it sends an air-wave path to the number dialled. The reception is either strong, weak, or not working at all. We know that with no signal, our call doesn’t go through. The same goes for pain signals.

When pain strikes, a signal travels into the spinal cord. From here the signal travels through the brain stem (medulla), and into the brain’s relay centre (thalamus), where the correct motor reaction is determined. These reactions could be getting away from that painful sensation or a natural automatic nervous system response, like rapid breathing and sweaty palms. What if we made sure that the signal never got through? Electrical stimulation can block the signal so your painful call is never received. 2

A man trying to get phone service in a forest.

What Conditions are TENS Machines Used For?

Health professionals and pain sufferers use TENS machines to treat a number of illnesses, acute pain, and chronic pain conditions. Electrical stimulation can help treat pain related to the muscles, joints, bones, and other painful areas due to its ability to block pain signals. TENS therapy can effectively be used for the following:

Joint Pain and Arthritis

Inflammation and swelling of a joint can cause pain, limited motion, and the possible wearing of the cartilage joint surface. Joint-related pain can affect any age group but is most often seen among seniors. Combining clinical treatment, medication and TENS therapy can help relieve joint-related pain. A TENS unit can provide instant relief for inflamed joints with its convenient ability to be placed directly on an affected area. The small pads can be placed on areas prone to arthritis and joint inflammation such as the knees or hands.

TENS therapy


Pain, fatigue, tenderness, and cognitive difficulties can all be symptoms of fibromyalgia. Placing the electrodes of a TENS unit on tender areas of the body can help block the pain signals produced by fibromyalgia. The TENS unit can also produce endorphins to mute pain signals and ease painful fibromyalgia symptoms during and after use.

what are the first signs of fibromyalgia


Relaxing tight muscles can help stimulate the blood and nerve circulation to the head, and help reduce the pain associated with headaches. For best results, headache sufferers should place the electrodes on the back sides of the neck while lying down.

A woman holding her temples in pain.

Back Pain

By relieving the pain and muscle tension, back pain sufferers often note an increase in their lower back flexibility, range of motion and strength. If you suffer from chronic back pain, we recommend massaging the painful area(s) with large electrodes, 3 to 5 times per day for at least 20 minutes each time.

TENS machines

You can also use TENS for these conditions and painful symptoms:

  • Menstrual cramps
  • Knee pain
  • Neck pain
  • Foot and ankle pain
  • Nerve-related pain
  • Sports injuries
  • Repetitive strain injuries

What does TENS Therapy Feel Like?

How does it feel to place electrodes on your skin and send a steady electrical current along your nerves? It actually feels great! After turning on the TENS machine you will feel a tingling sensation pass through your skin.

The current produces a massaging sensation that reduces the feeling of pain. As you turn up the intensity of the device you will feel the strength of the current travelling along your nerves. Some people feel the effects of pain relief in as little as 20 minutes. Watch the video below that captured first time TENS users reacting to the stimulation in slow-motion.

Do TENS Machines Really Work?

An important question to ask before buying your first TENS machine is: do TENS units really work for pain relief? Studies say yes. Researchers have found that TENS machines are capable of relieving pain, reducing muscle spasms, increasing tissue oxygenation, and increasing circulation.

Dr. Michael Ho commissioned two studies to investigate the effectiveness of TENS machines. The first study measured a single TENS device’s effectiveness and the second study reviewed the effectiveness of three devices against one another. See a summarized version of both studies below.

A doctor studying brain scans.

Clinical Trials & Studies

Dr. Stuart M. McGill's Study
Dr. Stuart M. McGill conducted a study to find out the effectiveness of DR-HO’S TENS device, the Pain Therapy System. The study looked at 41 men and women from a pain clinic. Scientific studies conducted by Dr. Stuart M. McGill, Ph.D. and commissioned by Dr. Michael Ho tested:

  • The effects of DR-HO'S muscle stimulation device on pain and muscle spasm
  • Changes in tissue oxygenation, as measured by Near Infrared Spectroscopy (NIRS), while treated with DR-HO'S muscle stimulation device
  • Description and comparison of traditional TENS to DR-HO'S TENS device (high intensity, modulated TENS)

Conclusive Findings

The above studies found that DR-HO'S TENS device can:

  • Significantly relieve pain
  • Significantly reduce muscle tension and spasms
  • Increase tissue oxygenation
  • Increase circulation

TENS Machine Side Effects

Are there TENS machine side effects? TENS machines should not create unpleasant side effects. If you experience side effects after using a TENS machine, contact your doctor to discuss the effects. There has been some evidence that suggests overusing a TENS machine can result in side effects. If you use a TENS machine for many hours at a time you could experience:

  • Muscle twitching
  • Muscle soreness
  • Tingling sensation
  • Skin irritation underpads 3

What Do I Look For in a TENS Device?

If you're wondering how to find the best TENS machine, consider the following variables:

Choose the Right TENS Machine for You

The TENS machine for you is the one that best suits your needs. Do your research and find out how to choose a TENS machine and most importantly, how to choose the TENS device that can best relieve your specific kind of pain.

TENS machines

Learn More About TENS Therapy

  1. DR-HO'S TENS Buyer's Guide: An Introduction to TENS Therapy
  2. How to Choose a TENS Machine.
  3. What is a TENS Machine?
  4. How Do TENS Machines Work?
  5. TENS Machine Side Effects: Is TENS Therapy Safe?
  6. What Is the Difference between EMS and TENS Therapy?
  7. Do TENS Units Really Work?
  8. What Conditions are TENS Machines Used For?
  9. Best TENS Machine: How to Find the Best Price, Quality, & Machine
  10. TENS Machine Reviews: Customer Reviews on DR-HO'S TENS Machines
  11. How to Use a TENS Machine - And How to Know You’re Using It Properly
  12. TENS Machine Prices: Compare Devices & Find The Best Deal
  13. TENS Vs EMS for Muscle Recovery
  14. What Does a TENS Unit do For Muscles?
  15. How to Use TENS for Muscle Recovery
  16. Can TENS Machines Help with Muscle Recovery Post Workout?
  17. Video: The Top 7 Questions People Ask About TENS
  18. How Does a TENS Unit Decrease Pain?
  19. Can You Use a TENS Unit While Sleeping?
  20. How Long is it Safe to Use TENS For?


  1. Transcutaneous Electrical Nerve Stimulation (TENS) - Topic Overview.” (2016). WebMD, http://www.webmd.com/pain-management/tc/transcutaneous-electrical-nerve-stimulation-tens-topic-overview.  
  2. Dr Tim Kenny, “TENS Machines.”(2015). Patient. http://patient.info/health/tens-machines-leaflet
  3. Schuster, Suann (2015). Side Effects of Overusing a TENS Machine. Live Strong. Retrieved from http://www.livestrong.com/article/270115-side-effects-of-overusing-a-tens-machine/
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