Disclaimer: I am not a doctor, nor do I play one on TV.

It's not something I am interested in or would do, but from a pragmatic perspective there are a few things to consider.

First and foremost, it's a stinging plant. If your partner has an acute allergic reaction to it, especially if there is bondage involved, you have a limited amount of time to apply treatment.

Secondly, once it's been applied it is a matter of biology. While there appear to be creams and lotions intended to stop or reduce the reaction, they may or may not work quickly enough, if at all.

Finally, aside from the location you apply the nettles to, you may not have much control over the process.

If you are going to try it, I would at least get those creams and an epi-pen before experimenting.