When your back and neck hurt, when you regularly have migraines and headaches, when you suffer from arthritis, sciatica, plantar fasciitis, have muscle spasms, when you experience pain while undergoing postoperative or injury rehabilitation, at some point it starts to drive you crazy. I guess you have heard about transcutaneous electrical nerve stimulation better known as TENS. Now, let’s see what health conditions can be treated with this kind of machine, how should you use it correctly, and where to place electrodes. We have also examined customer feedback to learn whether electrical stimulation is really able to reduce pain.

What is TENS?

This device is designed to relieve pain using a low-voltage electrical current. You can adjust settings to change the intensity of electrical stimulation depending on your needs. Namely, you can control the voltage as well as the duration and width of the pulse. The unit comes with electrodes that are intended to be placed on different parts of your body where the pain is experienced. Generated by the machine, the electric current passes through these electrodes, penetrating the skin. As a result, the therapy stimulates nerve pathways, mitigating the pain.

It might surprise you to learn that an electrical eel was a prototype for modern TENS machines. I am not kidding, ancient Egyptians used the shock delivered by that fish to relieve pain. A Roman physician Largus suggested standing on this fish as a way to get rid of headaches. Needless to say that electric eel shock could neither be adjusted nor controlled and, therefore, was dangerous. But the approach per se was revolutionary.

When electricity was invented, Benjamin Franklin carried out experiments to prove that electricity can be used to treat paralysis. The first electrical machines designed to relieve pain appeared two centuries ago. Though being a primitive version of today’s models, they worked well and grew in popularity very quickly. They could have been improved earlier, if it was not for the successful development of the pharmaceutical industry that came to the fore.

In the middle of the 20th century, many scientists came back to this technology and resumed research on the impact of electrical stimulation of pain sensations. This technology has been used in the former USSR for sports training, with the results showing up to 40% strength gains in trained individuals. In the 1970s, the first patent for a TENS machine was issued. As for EMS units, it was in the middle of the 1950s when Dr. Karl William Edmark, an American surgeon, developed a machine that used direct current to provide lower-energy shocks. And in the 1970s, the first guidelines for implementing these devices in the USA were developed.

How Does TENS Unit Work?

Wireless TENS + EMS Therapeutic Wearable System: photo

How does it reduce pain? The thing is that our spinal cord has a neural mechanism that either blocks or let the signals from the brain pass through. This “gate” can be closed, open or partially open depending on the signal received. When you use iReliev TENS machine, the pulsation it emits becomes the only stimulus that is perceived by your brain, while the pain is not felt anymore.

At the same time, this process helps to increase the number of endorphins, which are natural chemicals produced by the central nervous system and in their effect resembling morphine. Endorphins block the sensation of pain and make the person feel happy. Actually, they work the same way as drugs do, but have the advantage of being harmless naturally released chemicals that do not cause dependence.

Indications For Use Of TENS Machines

This matter has been scientifically studied and a number of trials have been conducted over the course of past decades. So there are enough facts to base on.

Upper and lower back pain. First of all, TENS units are intended to reduce pain in the upper and lower back. Researchers have confirmed that the therapy has a positive effect on the test users. Namely, as a result of the treatment, they visited their doctors less frequently and attended fewer physical therapy sessions in clinics. More importantly, less back surgery was reported. Apart from obvious health benefits and greater comfort, the treated patients were able to keep down their costs, even when the price of the machine was taken into consideration.

Sure, this treatment will not work for everyone and there are users suffering the back pain who reported little progress. And yet, more users are satisfied with the results and claim that the electrical stimulation helped to reduce the pain. In fact, much depends on how long the device was used and whether the electrodes were positioned correctly.

Pain in Joints. This is exactly what you need when you feel pain in your joints. Felicia C. Yu, MD from UCLA Center for East-West Medicine mentions joint pain from arthritis as one of the conditions for which TENS has been studied. Degeneration of joints is often caused by osteoarthritis and is accompanied with pain sensations. The TENS unit is able to reduce arthritis pain, especially if it is confined to one area of your body. Place the electrodes either above or below the sore joints, but not directly on it.

If you suffer from rheumatoid arthritis and the pain is perceived in several areas of the body, place the pads in the following order: first, treat the areas where the pain is the most severe and then, move on to the less painful ones. Users with chronic pain can use the machine as frequently as three times a day, unless otherwise recommended by their doctors. According to the trials, electrical nerve stimulation in combination with therapeutic exercises is very useful for treating knee osteoarthritis, with over 70% of the practitioners recommending TENS for this purpose.

Injury rehabilitation. Both modes can be useful in injury rehabilitation. The healing process is often accompanied by pain and sometimes taking additional medicine is not recommended for the patient. Besides, some drug combinations are counter-indicative and may have undesirable side effects. And this is where a TENS machine comes in handy. On the other hand, the EMS mode will help you stimulate your muscles to regain their strength. This kind of treatment will be particularly helpful for those who cannot train their muscles for some reasons or are limited in their movements.

Improvement of digestion. Indian scientists have conducted a study to determine whether electrical stimulation is helpful for the improvement of digestion. They placed electrode pads on the skin in the area of the parotid glands and compared the amount of salivation before and during the stimulation. The results show that in 45 out of 50 users of TENS machines salivation was increased, with the rate amounting to 0.5 ml per minute. The researchers have concluded that the results are statistically significant and the TENS machines should be considered effective in increasing the amount of saliva, which is the fluid that plays a crucial role in food digestion.

Spasms of muscles. Select the EMS mode to work the muscles by making them contract and relax. This kind of stimulation will help you to relieve muscle tightness immediately during the treatment. That said, the TENS mode can be beneficial as well. The thing is that pain increases the hardness of muscles and as the pain reduces, the hardness also decreases. These claims are supported by some governmental health institutions, such as the British National Health Service which indicates that TENS units can be used to reduce muscle spasms.

Headaches. TENS therapy is particularly helpful for people suffering headaches, with the efficacy being clinically proved. The study was conducted by Teheran scientists to find out whether this machine will help to reduce the duration, frequency, and severity of headaches. The patients were treated with 15 TENS sessions, with each lasting 20 minutes on a daily basis. The electrodes were placed on the skin of the forehead so that they could transmit stimulation to the trigeminal nerve. The researchers have found out that those using TENS machine experience headaches less frequently and they are milder.

TENS Unit Placement: How To Do This Treatment Correctly?

First, install 3 AA batteries. The batteries are not rechargeable and should be replaced when they run out of power. The unit comes with a useful feature, the battery status indicator, which will let you know when the battery is low. As a rule, the batteries are enough for 30-60 sessions depending on the intensity of use.

The next step is to insert a wired cable into the corresponding channel. For safety reasons, make sure that you insert it fully. After that, connect two small electrode pads or a large one to the wire. Keep in mind that the pads contain an adhesive layer that will dry in course of time and you will need to replace these parts with the new ones. Once all the parts are connected, place the pads on your skin, focusing on the sites where the pain is felt. The most common treatment sites include the abdomen, bottom, shoulders, the back, and front of thighs, the lower and upper back, and calf muscles.

Okay, now you can safely press the On button to activate the device. What is convenient about this unit is that it shuts off automatically when the time is over. There are 12 preset times, ranging from 5 to 60 minutes. So you will not need to count minutes and will be able to fully concentrate on the procedure. By the way, it is not recommended to remove the pads while the device is turned on as you may experience some painful sensations.

Since the unit offers two modes — TENS and EMS — you will need to choose the one you are going to use. This is an easy operation, all you will need to do is to press the Mode button and choose the therapy you are going to apply. We recommend you to start with the lowest intensity level, increasing it as you get accustomed to the treatment. You can choose the preferred intensity level by pressing CH1 or CH2 buttons. You should better do it with the pads on your skin so that you could select the most comfortable setting for you.

How to Use TENS to Treat Neck Pain?

If you sleep in the wrong position or have poor posture while sitting at your PC, you are likely to have neck pain which is also known as cervical pain. Is TENS treatment able to alleviate this kind of pain? Jordanian scientists have conducted a study that proves the efficacy of TENS as a treatment for neck pain. A group of patients suffering from musculoskeletal disorders was treated with TENS for an hour. The results showed that over 70% of the treated patients had gained significant improvement. However, the therapy proved to be most effective for patients with mild neck pain.

At the same time, it is very important that you place the pads correctly. You should not stick them directly on the neck. Instead, locate them in the upper part of the back or on the shoulders in the area close to the neck. Position one electrode on each side of the area. Adjust the unit to find the most appropriate level of stimulation intensity.

TENS Unit Placement For Sciatica

Electrical stimulation is effective in treating sciatica, however, much depends on whether the user places the pads on the right spots. How do you know where to place them? First of all, these are the areas where the pain is felt. Press gently on the spot to find out where exactly you should stick the electrodes. The right place is where the pain is most acute. If you are still unsure, focus on the area along the sciatic nerve. You can attach up to four pads, with two of them being placed at the top of the spot and the other two located beneath it.

TENS Unit Placement For Headaches/Migraines

This device can be used to treat headaches, migraines, as well as facial pains and neuralgia. There are several placement options. The first spot is the forehead for the trigeminal nerve stimulation. Secondly, the pads can be attached to the back of the neck. And thirdly, you can stick one electrode on the left temple and the other one on your right hand near the thumb finger.

TENS Unit Placement For Muscle Strains In The Back

For better results, we recommend that you ask someone else to glue the pads to your lower back. Of course, you can do it yourself, but in this case, there will be no guarantee that you will do it accurately enough. So the pads should be located on either side of the area where you feel the pain. Keep in mind that the electrodes should be at least 2 inches apart, while the angle does not matter.  

TENS Unit Placement For Ankle Osteoarthritis

Osteoarthritis is one of the common causes of ankle pain, but you can relieve it with the help of a TENS unit. Attach two pads to each ankle in the area where it hurts most. The most recommended spots include the calf muscle and around the ankle. The pads located on the right and left legs must be connected to different channels. You can change their intensity throughout the treatment, but you should better start with the lowest setting.  

TENS Unit Placement For Arm And Shoulder Trauma

Well, this can happen to everybody, even the healthiest person is not immune from getting his or her arm or shoulder injured. But should this happen to you, there is no need to tolerate the pain. In case of an arm trauma, one electrode should be attached on the inside part of the wrist, while the other one should be located on the inner bicep. Use the second channel for the other two electrodes which should be placed on the inner elbow. If you experience pain in the shoulder, apply the pads around the area where it hurts, at a distance of 2 inches from each other.

TENS Unit Placement For Hip Arthritis

With age, the hip joint can become damaged. That said, arthritis is one of the most common causes of pain in the pain, particularly in elderly people. In this case, stick two pads on the area where the pain is the most severe while the other two should be located around this spot. The first pair can be used at a lower setting than the second one.  

TENS Unit Placement For Knee Pain

You should not place the pads directly on your knee joint. The best spot for treating this kind of pain is around the knee — stick one electrode above it and the other one beneath it. If the pain is intense, use 4 pads, attaching them in the area surrounding the knee-cap.

how we tested "iReliev": photo

Vivid Impressions About TENS. How GADGETS’ Editorial Team Tested iReliev

I am a relatively healthy girl :) Perhaps, it is only the upper back and neck that hurt after long sitting at the computer and driving the car. Indeed, osteochondrosis is a disease of the 21st century, which we are persistently maintaining in ourselves by not doing sports and spending all day at the laptop in an anatomically unhealthy posture.
That is why I attend a physical therapist twice a year. But in between, iReliev is most suited to ease muscle tension. I have been using a handheld percussion massager for several years, but it is heavy and is not convenient enough to move it across the back as the hand gets tired. While a wireless unit is exactly what is needed — you can sit comfortably and keep working. It just feels like a very pleasant tingling.
I have tested all its programs, attaching the pads to my shoulders in order to relieve the neck pain. The most powerful one in the TENS mode is P8, in which the muscles contract involuntarily. It feels quite weird to have your shoulders bouncing on their own while you are sitting still. This is like a scientific experiment with a frog’s leg — in case you have seen this video — with the leg twitching when the discharge occurs.
We have also tested iReliev on our grandma, she has got sore joints in her legs, a dislocated shoulder and pains in other parts of her body. Previously, doctors frequently prescribed physical therapy to her, which helped her, so she liked the idea of having a similar device at home.

Testing TENS + EMS Therapeutic Wearable System: photo

What Do Consumers Say about iReliev? Reviews of TENS machines

In a review by Fairly Odd Rabbits, you can see how this device works. The blogger show unboxing of iReliev unit with 2 extra-large pads and 4 little square ones. All of them come sealed so that nobody could touch them or whatever. The package also contains brand-new batteries, connection cords and the unit itself. “What I like about this little unit is the size of a credit card,” she said, showing the machine. The blogger also draws attention to a loop that allows to hook up the TENS unit to your waist, for example. This makes the unit particularly comfortable for those who have chores at home but want to do the treatment regularly. Then, she stuck the pads where it was hurting. Make sure that your skin is clean and there is no lotion on it. “This is my new favorite thing,” she concluded.

Michael Doran, who is another happy iReliev customer. A father of seven, he has been struggling with arthritis in his back knees and hips for a long time. So he purchased iReliev TENS unit and decided to share his experience with this product. First of all, Michael notes the ease of use of this device. You can use it at home sitting in the chair or when you are out working. He says that iReliev unit really helps to reduce pain, something that makes it easier for him to move and function throughout the day. “I do not know what I would do without it,” Michael concluded, thanking the company for the products it offers.

Best TENS Unit | Consumer Reports

Let’s see what Consumer Reports says about TENS units. As a reference, Consumer Reports is a reputable monthly magazine with a research center based in New York.

When reviewing remedies for back pain, they have tested TENS units along with topical creams, massagers, heating pads, medicine, and other tools. The results have shown that the electrical nerve stimulator is the most effective in pain management, with almost one-third of back pain sufferers saying that it helped them a lot. Fifty percent of the interviewed consumers said that their TENS machines were of little help and the rest 20% did not try the device.

However, expert opinion varies significantly. For example, the Journal of Pain Management tested TENS machines and concluded that they were not very helpful. The Consumer Report magazine also refers to the Cleveland back-pain specialist, Kush Goyal, who suggests that the users should not expect too much as these machines do not provide enough electrical stimulation.

What Does An Electric Stimulator Do For Muscles?

While it is clinically proven that muscles can benefit from electrical stimulation, you should know what exactly to expect from this technology. Some advertisements tend to exaggerate the potency of this technology, which is why you should not be misled by unsubstantiated claims. Now, let’s have a look at what an EMS machine can really do for your muscles.


Treating muscle atrophy. German researchers have revealed that it can improve functional performances more effectively than voluntary training and counteracts “fast type muscle fibre atrophy, typically associated with sarcopenia”. They have conducted studies and discovered that this kind of stimulation can be effective in treating various diseases associated with muscle atrophy.

Rehabilitation. This therapy plays an important role in the rehabilitation of all sorts of injuries and is used by physical therapists to help their patients recover from surgery. Trials show that recovery in test groups is higher. In particular, patients recovering from a total knee arthroplasty and subjected to electrical stimulation demonstrated the improved walking speed in comparison with the patients who did not undergo this kind of treatment. Electrical stimulation will also help to limit muscles strength loss.


Building up physique. This kind of treatment cannot help build up muscles without physical exercises. Therefore, it cannot be considered as a replacement for physical exertion but is rather a supplementary measure that will help strengthen results. Electrical stimulation is intended for large muscle groups only, not the small ones like the calves, biceps, and triceps. The study carried out by the University of Wisconsin-La Crosse shows that after 8 weeks of treatment, patients did not experience firmness of their muscles.

Weight loss. Although this technology has been advertised by some manufacturers as a method of losing weight, the study found that there were no significant changes neither in weight loss nor in the percentage of body fat.


Can you use a TENS unit for plantar fasciitis?
Well, this therapy will not heal this disease but it is likely to provide pain relief. You should attach the electrodes to the calf and bottom of the foot. One session should last about half an hour, while the length of treatment depends on the severity of pain.

Is it safe to use a TENS unit for migraines?
Yes, of course. TENS is approved by the FDA for migraine relief. Keep in mind that the FDA conducts multiple tests before announcing that one or another device is safe for public use. Migraines are really disturbing as they cause intense pain on one side of the head, with the headaches lasting up to 3 days. You can safely place the electrodes over the head, without worrying about side effects.

What is the best TENS unit placement for foot neuropathy?
This therapy can be effectively used in moderate to severe foot neuropathy. Where to position the electrodes? Take the small pads and place them on your heels. Make sure that you have clean the heels thoroughly before the session.

Can you use TENS unit for sex to intensify orgasm?
Sure. Not only does electrical current brings pain relief, but it also causes sexual stimulation. Women can place electrodes on their vulvas, bottoms while men can position them on their penis and the surrounding area.

How to use a TENS unit on the penis?
A TENS unit will deliver gentle impulses of electricity to your penis. You should place one electrode on the top side of your penis and the other one in the area beneath the balls and above the anus.

Can TENS Machine Be Used For Cancer Pain?

In fact, we should divide the question into two parts — whether this therapy is effective against cancer-related pains and whether it is safe to apply in the tumor area. As for the first question, a number of studies reveal that TENS machines can be a beneficial complementary tool to relieve pain in cancer patients. This is particularly important because medication, though being effective, is fraught with side effects.

So as to back up this affirmation with supporting evidence, we will cite below the findings made by experts from the University of California. They have conducted a study that involved treating patients with cancer pain with TENS units. Those patients who reported pain relief were provided with these machines for use at home. The results show the improvement in almost 70% of patients who have been treated using these devices for two months.

TENS and cancer contraindications

Still, Lora Packel from Hospital of the University of Pennsylvania, warns that although TENS is a low-risk therapy, some practitioners say that it should not be applied directly over a tumor.

Jeffrey Loh, MD, notes that the effect of this kind of therapy is controversial. On the one hand, increased blood flow can stimulate the growth of the tumor as it influences the supply of oxygen to tumors. On the other hand, studies show that neither high-frequency nor low-frequency TENS machines can significantly affect blood circulation. That said, high-frequency units (above 80 Hz) are believed to should have a lesser effect on the circulation of blood and are, therefore, safer.

As for iReliev units, the operating manual says that cancer patients must not use them because “the effect of electronic stimulation on cancerous tissue is unknown”. Well, this is a responsible approach and we strongly recommend cancer patients not to apply a treatment that was not recommended or approved by your doctor.

TENS Unit Safety And Precautions

As a rule, users of TENS units do not experience side effects, but there are exceptions. Namely, their electrode pads may cause allergy in some people but it is a matter of a couple of percents. But basically, side effects occur in the case of using the unit at high settings or for unduly long periods. In this case, you may have an unpleasant feeling in the treated area, experience skin irritation or have your muscles twitching. 

These devices are not recommended for people with heart disease and must not be used over metal implants. Also, there is a perception among doctors that this type of treatment is contraindicated during pregnancy, so it is better to consult a doctor first.

Below, you will find some rules for safe use of TENS units:

  • Don’t apply the treatment for more than 30 minutes at a time. 
  • Keep the unit out of the reach of children.
  • Don’t remove electrodes from your body with the unit turned on.
  • Don’t place electrodes where you have skin disorders.
  • Don’t attach them to the eyes, nor should you put them in the mouth.
  • Don’t use a TENS unit when taking a shower.
  • Don’t go to sleep with the device turned on.

Are TENS Machines Good for Pain?

Yes, they can be beneficial. More importantly, these devices have been tested clinically, with the results proving that TENS treatment can alleviate pain in some cases. So researchers from the University of California conducted a study in a cancer center to find out whether this method would help to relieve severe cancer-related pain.

The tests have shown that this method was beneficial in almost 70% of patients over the course of two months. It is important to stress that not all patient turned out to be responsive to the treatment. But those who showed an improvement in pain symptoms were advised to use that kind of device at home.

Another study demonstrated that the device was able to improve cancer bone pain on movement. However, sometimes it goes the other way. There are tests showing no significant relief of cancer pain after TENS treatment, which means that this method is not for everyone.

Using TENS machines as an alternative to medications will help to avoid side effects associated with the latter. In addition, these devices can be a good supplement to medications in case the pain is severe. At any rate, first consult your doctor before treating cancer-related pain with a TENS machine. Since the drug-free approach has become increasingly in demand, more studies are obviously needed to determine the effectiveness of this particular method.