My Aikido Sensi used to do it to me to treat injusies for me.
He used rcycled jars with little valves fitted and a small compressor so he could comtrol the vacuum.

I say give if a try if the practicioner comes recommended.

It's been done for centuries so it can't be that bad.

It will leava a massive love bite the shape and size of the jar.

I saw in a magazine a while ago that some hollwood star had them on her back and wore a backless dress to some event or other, it looked pretty cool.

But if you are not prepared for the [temporary] marks it can be quite alarming.