When should you not use a TENS machine?


A popular alternative to the use of painkillers during treatment is through a transcutaneous electrical nerve stimulator (TENS). The TENS is a small, portable, and battery-operated device that is worn on the body. The TENS machine is attached to a patch and when using this machine, the user attaches the patch to the skin.

Through this adhesive, small electrical impulses are transmitted to the body, like electric shocks with low voltage. These electrical impulses will affect the spinal cord and brain, stimulating the production of endorphins, the body’s natural painkillers. This substance helps relieve pain and promote feelings of happiness. However, there are a few caveats in using a TENS machine.

In this article, we will tell you when you should not use the TENS machine.

Mechanism of operation of the TENS machine

The TENS machine produces small electrical impulses transmitted through electrodes placed on the skin. These electrical impulses produce stimuli, which are then sent to the brain, dispersing pain signals transmitted from the nerves and spinal cord to the brain.

Therefore, when pain signals are blocked by small electrical impulses from the TENS machine, the brain will receive fewer pain signals and the user will feel less pain.

The TENS machine can generate electrical pulses of different frequencies. Specifically,

  • As normal usage, the TENS machine produces electrical impulses at high pulse rates of 90-130 Hz, which help block pain signals being sent to the brain. According to pain control theory, the nerves of the brain and spinal cord (central nervous system) receive pain signals and then we feel pain.
  • However, when this central nervous system closes and does not receive the signals that are transmitted, we will not feel pain. When using the TENS machine, electrical impulses will stimulate some painless nerves and close the gate. According to some studies, the brain receives signals from the TENS machine faster than pain signals, so the brain will be busy processing signals from the TENS machine instead of the pain signals.
  • When the TENS device is set to low (2-5 Hz), the body is stimulated to produce pain relievers called endorphins. Similar to morphine, it blocks pain signals.

Use a TENS machine to relieve pain in cases

When you experience the following problems, the TENS machine can help relieve pain and muscle spasms including:

  • arthritis
  • period pain
  • pelvic pain due to endometriosis
  • Knee hurts
  • neck pain
  • backache
  • sports injuries
  • In particular, when pregnant women have pain during labor, the TENS machine can also be used to relieve pain but requires medical supervision.

Cautions when using the TENS machine

Using a TENS device for home treatment is a safe method, but as with most treatments, some treatments should not be used and should be carefully read the instructions for use. The electrodes for a TENS unit should not be placed:

  • Do not place the electrode patch on burned or irritated skin.
  • Do not place the electrode patch on the neck, eye area, mouth or near the heart.
  • Do not apply the electrode to flow sensing areas.
  • Avoid using the TENS machine in areas with water, such as in a bathtub or shower.
  • Do not use the TENS machine when driving or operating machinery.
  • Should not place on parts of the body that are numb, unless advised by your doctor.

Those who should not use the TENS machine

The TENS machine is mainly used for pain relief caused by muscle, joint, and nerve problems. If you experience abdominal pain, chest pain, or headaches, the TENS machine is not an effective pain relief tool. Unlike oral medications, the advantage of TENS is that there are no side effects. However, in the following cases we should not use the TENS machine for pain relief:

  • Do not use the TENS machine yourself to relieve pain if the cause of the pain is unknown or has not been diagnosed by a doctor.
  • Pregnant women should not use the TENS machine unless specifically medically advised – or during labor.
  • Do not use in combination with a pacemaker.
  • People with a history of epilepsy or heart disease.


In summary, here are the basics you need to know before using the TENS machine. Make sure you read and understand them so that you can use TENS safely, protect yourself from injury, and achieve the highest efficiency. You must remember to not use the TENS machine when operating machinery or taking a shower. In short, you should invest in a TENS machine to help ease the pain.