Imuneoak was issued by the Bell System for rural linemen in areas with poison oak…
It was a drop added to water to buildup tolerance…
It was discontinued maybe 40 years ago and I spoke to the lab who said it was a business not to spend the vast amounts needed to update the old patent medicine to modern clinical testing standards.
There are also tablets under the tongue claiming the same.
I get it terrible but by being careful and using barrier lotion can manage…
Sitting on my CAT dozer working fire trails I would get it bad on every square inch of exposed skin from just the dust.
By not dozing in hot dry dusty conditions was one way to avoid because a few days after a good rain with soil having a lot of moisture no dust…
I've seen a homeopathic "remedy" (highland's) which purports to help if you have a rash. Thing is with homeopathy, the "6X" "active ingredient" means that there's 10^-6, a dilution of one part in one million, of the thing, like the poison oak (assuming they actually put the ingredient in there; at those dilutions you're not going to know).
So a 50mg tablet with 6X poison oak will have at most 50x10^-6 mg poison oak in it, or 50 nanograms.
It may be apples and oranges, but they're doing oral immunotherapy these days to desensitize kids who have peanut allergies - one of the more deadly allergies to have - and the treatment starts with 3mg of peanut protein and goes up from there. That's a hundred thousand times more than what's in the homeopathic poison oak remedy.
Even so, perhaps 50 nanograms of poison oak, ingested, is enough to train the body against reacting, but that's very close to zero. Studies have been done in the past based on rumors of people reducing sensitivity by eating leaves (quantities definitely higher than micrograms let alone nanograms), but the studies have all shown in the negative, and the common wisdom is that people get more reactive, not less, with time - though I've personally gone the other way, but not by eating leaves.