Doctors have been using electricity to help relieve pain since the mid-1960s. Transcutaneous electrical nerve stimulation (TENS) uses mild electric current to help give pain relief. Research says that TENS therapy may help some people get relief from acute, chronic, or stubborn pain.

The main use for TENS is to ease pain. TENS may help ease pain from conditions, including:

• Arthritis
• Tendonitis
• Bursitis
• Surgery
• Migraines or other headaches
• Wounds
• Injuries
• Nerve pain
• Fibromyalgia
• Back pain

Some experts believe TENS therapy has the most use for treating nerve pain.

A TENS system includes:

• A small device powered by a battery
• Two wires that branch off into more wires
• Electrode pads to be put on the skin near the site of pain

Some TENS units may be small enough to fit in your pocket. When you turn on the device, the mild electrical current travels to the electrode pads placed on the skin. You can adjust the frequency and strength of the current.

During treatment, you may have a mild tingling feeling or feel warmth. The tingling feeling may briefly stop you from being aware of the pain. TENS may help your body release natural pain-reducing chemicals. These are called endorphins. Some studies suggest that electric current stimulates nerve cells to block pain signals.

A TENS session often lasts 5 to 15 minutes. It can be done as often as needed. Sessions are most often done by a physical therapist or other doctor. TENS may also be prescribed for use at home.

Hundreds of studies have been done on TENS, but most have been small or not well designed. For this reason, some experts say TENS can only give short-term relief. Long-term relief hasn't been proven.

More research is needed to know if TENS can help many kinds of acute or chronic pain.

For cancer pain, more research is needed before TENS can be advised as a treatment. TENS may give short-term relief for some nerve-related cancer pain, according to the American Cancer Society.

TENS is generally seen as safe. But it has risks just like any treatment.

If the electrical current is too high or the electrodes are put on the wrong part of the body, this can burn or irritate the skin. Areas to avoid include the brain, heart, eyes, genitals, and throat.

Some people should not use TENS. This includes:

• People who are pregnant
• People with heart problems
• People with an implanted device, such as an infusion pump, pacemaker, or defibrillator