TENS therapy is a popular form of pain relief, but it's important to understand when it should and should not be used. Research has shown that TENS can be effective in treating certain types of pain, but there are some situations where it should be avoided. The effectiveness of TENS therapy is still being studied, and there is a lack of randomized trials comparing it to conventional treatments. TENS works by targeting small diameter, high-threshold afferent skin afferents (A-delta) to block the transmission of nociceptive information in nerves and stimulate other analgesic mechanisms.
While it can provide short-term relief, it does not cure pain and more research is needed to determine its place in pain treatment. TENS machines are generally similar in quality, so it doesn't matter too much if you buy a basic model. Acupuncture-like TENS (AL-TENS) is a hyperstimulation method that is sometimes used for people who don't respond to conventional TENS. However, the results are usually short-term and there is still disagreement about which conditions it is appropriate for.
You can use TENS all day long, but you should not use it while driving, operating machinery, or taking a bath or shower. Conventional TENS uses mid-range frequencies and durations and is the approach that was first used with people who were unfamiliar with the modality. It's best to get a proper evaluation before buying a TENS machine so you can find out if it's right for you and learn how to use it correctly. Using a TENS unit while driving or operating heavy machinery involves theoretical risks, so it's best to avoid using one during these activities.
However, some studies have suggested that this may be more of a medico-legal maneuver than an actual risk. Before using a TENS unit, people should undergo a formal pain evaluation by an experienced professional and receive clear instructions on how to use the device.