How Does A TENS Unit Work And Could It Help Me?

how does a tens unit work

If you or someone you love suffers from chronic pain, it’s crucial to know everything you can about your treatment options. A TENS, or transcutaneous electrical nerve stimulation, unit is a non-invasive treatment option that may offer relief. If you have ever asked yourself, “How does a TENS unit work?” here’s what you need to know.

What is a TENS unit?

TENS units are a battery-powered pain relief treatment option that has few side effects or risks. Utilized on the outside of the body, TENS units are considered non-invasive and safe for use for many in pain.

The TENS unit itself is about the size of a small cell phone. One or two sets of leads go from the device and attach to self-sticking pads (electrodes) you place on your body. These electrodes are strategically placed to deliver mild electrical current. You control these currents directly with programmable buttons on the unit.

Each TENS unit has two channels with two electrodes each to deliver electrical stimulation. Whether you use two or four electrodes is something to discuss with your doctor and depends on your pain location, as we’ll discuss.

How does a TENS unit work?

So how does a TENS unit work?

Chronic pain is defined as persistent pain that lasts for longer than three months. Generally speaking, you sense this pain because of your neurons. If you hit your elbow, the nerves in your elbow send a signal to the brain that is then interpreted by the brain and translated. Pain signals are sent back along the path of the nerves, and pain is felt in your elbow. This process is nearly instantaneous.

While pain signals are a necessary and protective part of human biology, sometimes neurotransmitters incorrectly switch on, sending chronic, frequent (or sometimes constant) pain signals to the brain. This can result in debilitating chronic pain. Additionally, when chronic pain occurs, the brain produces more glutamate, a brain chemical that stimulates pain, and less natural opioids and serotonin that might help relieve pain.

This can create a cycle of increased and worsening pain. TENS units serve as a disrupter to pain signals and can bring balance back to your brain chemistry. Remember the bumped elbow? When we feel pain, our usual response is to put our hands where it hurts, rubbing or grasping the elbow. This can make it feel better. We have replaced a pain signal with the signal of rubbing or warming as we touch our elbow.

The TENS unit does something similar. Mild electrical currents move through the leads and electrodes on your body. Instead of a pain signal, neurons in the brain receive a mild buzzing or tingling sensation in the spot. This electrical signal intercepts or blocks the pain signal transmission.

tens unit pd

Why does a TENS unit work? 

Right now, it’s not 100% clear on exactly how a TENS unit relieves pain. One leading theory is that the electrical stimulation keeps nerves so busy that they are not able to process pain signals. These same high-frequency electrical pulses may encourage the brain to switch the balance of chemical production to more natural pain relievers (e.g., serotonin).

Regardless, many people find non-invasive pain relief from this type of device.

Which conditions can I use a TENS unit for?

TENS machines may provide pain relief for a variety of previously intractable pain conditions, including:

  • Sciatica
  • Neck pain
  • Diabetic peripheral neuropathy
  • Lower back pain
  • Osteoarthritis
  • Tendinitis
  • Bursitis
  • Shoulder pain
  • Migraines
  • Headaches
  • Fibromyalgia

Let’s look at each of these in more detail.

Sciatic pain

Sciatic pain (also referred to as sciatica) is not in and of itself a pain condition but rather a particular type of pain that is produced from different conditions (e.g. herniated or bulging discs). Nevertheless, it is very common and effectively treated with a TENS unit.

The sciatic nerve is the longest, widest nerve in your body. It attaches at the lumbar spine (lower back) and runs across the buttocks and down the hip on the outside of the leg all the way to the feet. Any compression or pressure on this nerve can cause excruciating pain that radiates from the lower back to any point along the nerve’s pathway.

Other symptoms of sciatic pain can include numbness in the legs and feet and a burning sensation. Symptoms are most often felt on one side of the body and will continue to worsen without treatment.

Once the cause of the sciatica is determined, a TENS unit can provide relief from pain that is non-invasive and safe while you and your healthcare team address the root cause of your pain. The mild tingling sensation provided by the TENS unit replaces the pain, allowing you to participate in physical therapy and other active treatments to relieve your pain. .

Neck pain

Neck pain is becoming more common as we spend more of our days hunched over screens and steering wheels. When pain becomes a pattern, chronic pain may persist.

TENS unit therapy is one part of a comprehensive neck pain management plan that can also include ergonomic changes in our daily lives and physical therapy or exercise.

Diabetic peripheral neuropathy

Diabetic peripheral neuropathy is a type of nerve pain that originates from the spine as a result of nerve damage. This damage most occurs due to wildly fluctuating blood sugar levels found in diabetic patients. This pain can be incredibly difficult to treat and debilitating as it progresses.

Peripheral neuropathy is not only caused by diabetes. It can also occur due to the following:

  • Vitamin deficiencies
  • Alcoholism
  • Autoimmune diseases
  • Certain medications

Regardless of the causes, TENS units are one way to approach management of this complex condition.

Lower back pain

Lower back pain from any cause is a candidate for TENS unit therapy.

Because there are few side effects, TENS machines may even be a good first-line treatment for acute pain that is long-lasting but not yet severe and chronic.


Osteoarthritis is a form of arthritis that is a wear-and-tear condition. As we get older and use our bodies, the cartilage that protects joints begins to gradually deteriorate. Once this occurs, painful bone-on-bone rubbing happens, causing pain and inflammation. If left untreated, bone spurs can also occur, turning a mild pain experience into a severe one.

As the most mobile and hard-working part of the spine, the lower back is a prime target for osteoarthritis and the pain that comes with it. TENS unit therapy can be a solid treatment option to reduce pain.


Tendinitis can be notoriously difficult to treat. When tendons in the body become strained, stressed, or injured, pain can occur. In many cases, pain also leads to lowered activity levels, which in turn leads to longer healing times.

This vicious cycle can be broken by a TENS machine. Besides pain relief, a major TENS unit benefit is that it allows people in pain to be more active. After the acute phase of most injuries is over, physical activity is key in healing. This is true with tendinitis in most areas of the body.


Bursitis can occur in movable joints like the knees, but it also occurs in the lower back when the bursa that cushion your vertebrae and provide shock absorption begin to deteriorate or herniate.

Before surgery, a TENS unit and physical therapy may be a good choice.

Shoulder pain

The shoulder girdle is a complex piece of anatomy that has four joints that are highly mobile. These joints are surrounded by connective tissue and muscle, all of which are susceptible to injury from accidents or repetitive use.

Chronic shoulder pain can impact your daily life, making simple actions like lifting groceries or waving to friends across the room painful. The mild tingling of TENS can help you continue your active life with less pain.

tens unit

Migraines or headaches

Migraine headaches are not normal headaches that can be treated with medication or a little rest. These headaches can become chronic and intractable, responding only to prescription medications that often come with a host of side effects.

TENS therapy is a researched-backed option that is incredibly effective in the treatment of migraines.


Fibromyalgia is a connective tissue disorder that comes with other symptoms, like digestive issues, debilitating fatigue, and widespread pain. For many years, people with fibromyalgia (primarily women) were ignored in their suffering, with some doctors and researchers believing that the pain was in their head.

TENS machines can help reduce the pain and fatigue in many people who suffer from fibromyalgia, without the many side effects that come with prescription medications.

What are TENS unit benefits and research?

TENS unit benefits are easy to see.

  • TENS unit therapy is affordable: Insurance often covers the price of these units, but if not, a TENS machine can be as little as $100 (even over-the-counter)
  • Most people can use TENS: Pregnant women and people with pacemakers are not usually able to use TENS therapy, but it is generally safe for others
  • TENS therapy helps you stay active: Because the unit is most effective when you are active, TENS therapy encourages you to keep moving during treatment


Many TENS unit benefits are gaining support in the research.

In a randomized, controlled trial of 301 patients with fibromyalgia, 44% of those using TENS unit therapy experienced significant pain relief when compared to patients who were not using the therapy. An additional 29% of TENS users reported at least a 30% reduction in pain and a drop in levels of fatigue. And, 70% of the patients using the TENS machines reported feeling much better after four weeks of treatment.

For migraine pain, TENS unit therapy offered relief to an astonishing 81% of people who used it. The results, reported in The Journal of Headache and Pain, are great news for those who suffer from frequent migraines that impact their lives (and are not responsive to other treatments).

Other findings include:

Many of these studies point out that knowing how to use a TENS unit, including properly calibrating the level of electrical stimulation and accurately placing the electrodes, is key to a successful treatment.

How to use a TENS unit

The first thing to understand about how to use a TENS unit is that you will get the best results when you work with your doctor. Rather than just treating one symptom, your doctor will help create a comprehensive treatment plan for more effective pain management.

To start, placement of the TENS electrodes is crucial. Your doctor will help, but here are five general tips.

  1. Identify the exact location of the pain (as closely as possible) and focus on the most painful area
  2. Use either two channels or four channels for a proper circuit (never just one or three)
  3. Place electrodes at least an inch apart and make sure they are not touching
  4. Do not place electrodes directly on a joint that may loosen the pad with movement
  5. Electrodes can be directly across from each other, one above the other, or diagonal to each other

The distance between the electrodes changes the electrical signals. If you have pain over a wide area of your body, place the electrodes at either end of that pain. If the pain is in a small area, place the electrodes closer to each other at the exact location. Finally, if the pain is in a joint, placing electrodes on opposite sides of the joint can help.

It may take a few tries to get the exact placement of the electrodes down for optimal pain relief. Working with your doctor can help.

Side effects

The most common TENS machine side effect is skin irritation at the site of the electrodes, a condition that can be addressed by using hypoallergenic pads.

Some patients may also find the mild buzzing to be too much. Many get used to it over time or their doctor can recalibrate it for more comfort. Some patients can also develop a tolerance to TENS. Address this by taking a break from the treatment to allow your nerves to rest.

Could TENS unit therapy help me?

Chronic pain can be treated, but only you and your doctor can decide if a TENS unit is right for you.

Getting a proper diagnosis of the condition causing your pain is a crucial first step. Treating any underlying causes of pain may go a long way towards relief. A TENS unit could help you walk those final steps in getting your life back.

Arizona Pain can help you decide is a TENS unit is right for you. Get in touch today for a consultation.