context: You may have considered many kinds of treatments for your chronic pain, including medication, physical therapy, and perhaps surgery. One other option that has gained popularity is transcutaneous electrical nerve stimulation, or TENS. A TENS machine is small -- about the size of an i Pad mini. It's connected to a series of electrodes, which are put on your skin to deliver a low-voltage electrical charge. The electrical pulses stimulate nerve fibers in the area where you have pain and reduce the pain signals to your brain. The electrical charge may also cause your body to release natural hormones that decrease your pain levels. You can get TENS treatments from a machine you use at home or from a device at your doctor's or physical therapist's office. There's not a lot of good research on TENS, and some of the results are conflicting. But there is evidence that it may work for some people. The amount of pain relief it provides, and for how long, varies from person to person. Generally, TENS may provide pain relief at first for many people who try it. But after using it for a few months, it appears to become less effective. It's best to think of TENS as something to try in addition to other methods of managing pain. It's not for all types of pain. But it might help with: Pain after surgery. It's most effective in treating mild to moderate pain after several types of operations, including heart surgery, chest surgery, hysterectomy and other gynecological surgeries, orthopedic surgery, and abdominal surgery. Arthritis pain. TENS may ease arthritis pain. The results are mixed on how effective it is for rheumatoid arthritis. Diabetes nerve damage (diabetic neuropathy). Studies show that TENS can help relieve pain from diabetic nerve damage, most commonly in the hands and feet. Spinal cord injury pain. At least three studies on TENS and spinal cord injury pain have shown improvements in this kind of pain, which is hard to treat. Facial pain. TENS appears to be effective against a kind of facial nerve pain. It may also make activities like chewing, talking, and sleeping more comfortable for people with this condition. Menstrual pain and labor pain. Small studies suggest that TENS provides relief from painful menstrual cramps and back pain related to the menstrual cycle. Research has also found TENS to be at least as effective as other nondrug pain relief options during labor. Fibromyalgia. It can be effective as a short-term treatment for fibromyalgia pain. It shouldn't. There are several different ways of delivering the TENS electrical current. Lower-intensity TENS may be less effective at relieving pain than higher-intensity TENS. Some experts recommend that TENS should be given at a strong, but still comfortable, intensity -- the highest intensity that does not cause pain. It's generally considered safe, with fewer side effects than some other types of pain relief. There have been some reports of people getting mild electrical burns when they use their TENS unit improperly. So you should learn how to use a TENS unit with supervision from an experienced doctor or physical therapist. There are some people who shouldn't use TENS. They include pregnant women (because it may induce premature labor) and anyone who has a pacemaker or other implanted heart rhythm device. Don't use TENS in an area where you have numbness or less feeling, because you could burn yourself.