Vos, i'm not trying to bad mouth neem, i'm sure it works wonderfully for a lot of people, and i don't dispute it's effectiveness when used properly. however, some people can have an allergic reaction to it.
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0536.2012.02099.x
when i haven't used any neem oil...which is 99.9 % of the time, and i work in my flower room, i do get itchy, but that's all i get, and it stops when i take a shower. i've tried neem 3 times, two different products, and both times, i not only got itchy, i got a lumpy red rash as well, that took a couple of days to go away. i also find the smell very unpleasant, like rotted sesame oil, and it seems to linger for a long time to me. i can get the rash up to a week after using the neem oil if i touch the plant i used it on again. when i quit using it, the rash doesn't happen, and it doesn't smell like the dumpster behind a Chinese restaurant in my tent.....what conclusion would you come to with this evidence?