TENS stands for transcutaneous electrical nerve stimulation. It's a safe, non-invasive method that may help relieve pain in some people.

A TENS unit is a portable, battery operated programmable device consisting of an electrical signal generator attached to a set of electrodes. It delivers a small electric charge to the skin near the painful site. The electrodes may be placed:

• On the skin directly over the painful area
• In other areas, such as where nerves reach the skin
• Over trigger points (areas that can lead to pain)
• Over acupuncture sites (areas that are stimulated during acupuncture treatment)

Never place TENS electrodes over the large vessels in the neck or near the throat. Also do not use it near the eyes, heart or brain.

TENS therapy has been used to try to relieve acute and chronic pain due to surgery, injury, wounds, migraines, tension headaches, cancer, back pain, arthritis, bursitis and tendonitis. Evidence shows that TENS is sometimes effective for relieving acute pain (pain that lasts less than 3 months). But, more research is needed. Although it is sometimes used for chronic pain, studies do not yet show conclusively that TENS is effective for chronic pain relief. More research is needed to see how well TENS therapy works for different types of pain.

How does TENS work?
Research is ongoing as to exactly how TENS works to stop pain. The main theory is that electrical impulses from TENS compete with the painful stimuli entering the spinal cord. Unpleasant pain signals may be effectively shut out while using TENS. It is also thought that TENS may help to increase production of endorphins, the pain-killing chemicals in the body.

What is involved with TENS treatment?
TENS is usually given as part of physical therapy for a period of weeks. You will work with your physical therapist to decide on the frequency of treatment that's best for your condition. You may have TENS along with medication and active forms of physical therapy (exercises).

What does TENS feel like?
TENS creates a pleasant, comfortable sensation. Some people feel slight pins and needles. You should never feel pain or turn the unit up too high.

Can I use TENS on my own?
Your doctor or physical therapist may prescribe TENS for home use. He or she will need to show you exactly how to use the TENS before you start. Ask about the different setting (frequencies and strengths) and which one is best for you. The best settings for you may be different than it is for someone else. It may take some time before you find what works best for your own pain control.

When do I use TENS and for how long?
TENS is often used during activities that cause pain or when pain is the worst. Ask your doctor how often and when you should use your TENS unit.

Who shouldn't use TENS?
TENS unit should not be used:

• If you wear a pace maker or have another type of implanted heart device
• If you are pregnant
• If you have a spinal cord stimulator (another device for pain treatment)
• If you have a pump that is used for medication or feeding
• While showering or taking a bath

The TENS should not be placed over large blood vessels of the neck. This could lead to a dangerous drop in blood pressure. Nor should the electrodes be placed near the throat. The electrical signals can make the throat spasm and close up, making it hard to breath. The device should not be placed over areas of the skin where there is nerve damage. Using TENS incorrectly can burn or irritate the skin.