formic acid is also a rapid fixitive and decalcifier. We use it to treat bones to make them softer for histology so we can slice them into 4um cross sections (thats how microscope slides are made, then we stain them with pretty colours)

It's called urtification (after the latin for nettles, Urtica dioica) , and humans have been doing it forever for exactly the reasons she mentioned.

You body will acclimate to the feeling after repeated exposure.

My partner spent so many years removing nettle from wetland restoration sites that she doesn't even feel it anymore.

So she was literally fighting inflammation with inflammation? That's either badass, stupid, or both 😄