There are lots of guys who session with female body builders who request it and get knocked out regularly. If done right it must not be too dangerous.

Dome incorrectly or too often I can't help but think it can be dangerous.

Here's a long thread with lots of names of female body builders who do them. It started a long time ago so some of them are retired. Page 4 has a discussions about their safety.
https://saradas.org/index.php?topic=188204.0