RhoGam is a vaccine like globulin shot that was developed in the late 1960s to keep a Rh negative woman from becoming sensitized to the Rh positive blood of her fetus in the unlikely event blood mixing occurs. Rhogam works very much like an immunization.
However, some new research has shown that TENS may be effective for reducing pain in people who have fibromyalgia, especially in combination with other treatments, such as exercise. Fibromyalgia is often treated with various medications to relieve pain and improve sleep.
That is what TENS units are designed to do, relieve pain. But not every person is the same, so adjustments can be made to obtain optimal relief over time. There is no limit to how long or how often a TENS unit can be worn, it is at the discretion of the prescribing practitioner.