Mechanically it’s probably the same as allergy exposure therapy(https://www.npr.org/sections/health-shots/2023/04/08/1168714...), which comes in a lot of varieties including oral/digestion.

It’s effective in a clinical setting and honestly too dangerous to recommend in home settings without several layers of precautions.

But, in theory, highly specialized exposures to particular local allergies would be more effective than most of the clinical studies. And that’s what I would expect is driving the folk remedy.

Worth noting, almost all of the treatments like this are VASTLY more effective when done at younger ages. But they are also even more dangerous. So please speak to an allergist first and don’t do stuff you just read online.

Some research suggests it works, some research concludes it is no better than placebo. :shrug:

Eh, good enough for me. Pretty sure placebo won't cut it with the severe allergy of my family members so we can just try and see.

(if it does have an effect then I wouldn't be surprised if it also matters if the nettles were regionally sourced or not - IIRC there were some studies suggesting that that mattered for the effectiveness of honey helping with seasonal allergies or not)

My SO swears raw milk helped for this. Sourced locally it contained local allergens and helped with seasonal allergies.