A transcutaneous electrical nerve stimulation (TENS) unit is a battery-operated device that some people use to treat pain.

TENS units work by delivering small electrical impulses through electrodes that have adhesive pads to attach them to a person’s skin.


The same electrical impulses also stimulate the body to produce natural pain relievers called endorphins.

In this article, learn more about the uses of a TENS machine and the research on its effectiveness.


TENs unit
TENS units can help treat and manage pain.

TENS units may help treat the following symptoms:

They may also alleviate pain that results from the following conditions:

A TENS unit has controls that allow people to administer an appropriate level of pain relief. People can achieve this by altering the following aspects of the electrical current:

Intensity: A dial allows the user to adjust the intensity of the electrical stimulation.


Duration: The duration is the number of microseconds that the current enters the skin for during each pulse.




Possible side effects

Redness rash on skin
If the adhesive pads cause redness or irritation, hypoallergenic pads are available.





When to avoid TENS


This recommendation applies to the following people:

  • People with epilepsy: Applying electrodes to the head or neck of people with epilepsymay induce seizures.
  • People with heart problems.

Does it work?

Due to a lack of high-quality research and clinical trials, researchers have not yet determined whether TENS is a reliable treatment for pain relief.

One study found that TENS treatment provided temporary pain relief for people with fibromyalgia while the machine was in use.


Several factors may influence the effectiveness of TENS:


Research shows that people who use a TENS unit on a daily basis at the same frequency and intensity can develop a tolerance to the treatment.


To prevent this from occurring, people can alternate between LF and HF TENS within each treatment session.


Stimulation intensity


According to a 2014 review, HF TENS treats pain more effectively than LF TENS. In fact, many studies have found LF TENS to be ineffective.

Given that HF TENS is a more effective pain reliever, experts recommend that people apply the highest-intensity TENS that they can tolerate.

Electrode placement




How long does pain relief last?

TENS unit being used on persons back
A person who repeatedly uses a TENS unit may build up a tolerance.

The duration of pain relief after using a TENS unit can vary. Some people report that their pain returns as soon as they switch off the device. Others continue to experience an adequate level of pain relief for up to 24 hours.



The research on using a TENS unit for pain relief has so far yielded inconsistent results due to a lack of high-quality scientific studies and clinical trials.

Some research suggests that TENS treatment can relieve pain, but this may be dependent on certain factors, such as the affected area of the body and the treatment intensity. Knowing how these factors affect TENS can help people use it more effectively.

Most people can use a TENS unit safely, and few will experience side effects. However, it is best to speak to a doctor before trying TENS either as an alternative treatment or in combination with other methods of pain management.

TENS units are available to purchase at some pharmacies and online.