There is no medical research showing that TENS, or transcutaneous electrical nerve stimulation, is effective in treating back pain, according to WebMD. However, TENS is generally safe for most patients.
Sciatica is a kind of back pain caused by problems with the sciatic nerve, which runs from the lower back into the leg, explains WebMD. The pain of sciatica begins in the lower back and spreads to the buttocks, hips and leg.
TENS treatment dates back to the 1960s, according to WebMD, based on the gate control theory of pain. The electrical stimulation of the nerves is believed to close a "gate" in the spinal cord, blocking the pain sensation. Another theory for how TENS could reduce pain is that the stimulation of the nerves causes the body to release endorphins, which are natural pain killers.
WebMD cautions patients not to use a TENS unit without first consulting a doctor. Patients should carefully follow the doctor's instructions on when and how to use TENS. Some patients, such as pregnant women or patients with pacemakers, might be told by their physicians not to use TENS treatments.
Patients should not leave electrodes in place for long periods of time without checking the skin underneath for irritation or burns, according to WebMD. They should not place TENS electrodes on broken or irritated skin, and must never use a TENS unit with a heating pad or an ice pack or while driving or sleeping.