A. That depends on what they are trying to accomplish by doing so. I would recommend an evaluation before you start anything to make sure that your spine could handle that type of therapy. To stretch out the lower back, there are more effective ways, but an inversion table particularly can affect the disc because of the decompression that can be created, it may relieve disc symptoms, but may not increase disc height. After I evaluate a patient to make sure that a patient won't hurt herself/himself, I do recommend them after a patient's condition has stabilized, but not during an acute flare-up. They are most effective if you start with a gradually increasing angle beginning at about 15-20 degrees for a few minutes a day (5-10) and then seeing the response. If you don't have any adverse reactions, then I would recommend incrementally increasing the angle until a patient is vertical. Increasing the angle too quickly may lead to spasm or injury, and depending on what underlying problems may be there, may cause damage. So, in short, I do think they are effective and recommend them, but only after confirming that it would not likely hurt a patient after an evaluation, and only when a patient is in the supportive or maintenance stage of care. I do not think it would be effective to just stretch the back. Under normal circumstances, I think they are generally safe, but the increased pressure on the blood vessels may lead to a stroke in rare occasions. Proceed with caution.