I've bought 5 pu erh tees. I've noticed some of them give me a numb tongue for days (2-4). Haven't pinpointed which of them has this issue but I know one for sure: 2012 Dayi Pu Zhi Wei.
Like the above mentioned one I drank yesterday, and the numbness gets stronger the day after. I typically prepare my tea just by putting the tea strainer in the cup and let it stay there. To be fair, the tongue isn't completely gone but a feeling of irritation or burn. But yesterday I deliberately waited for the tea to cool down to a point I couldn't get burned.
I googled and some said this could be pesticides? How dangerous is that?
How common is it? Can it be avoided? Does some brands don't have this?
It's not something you want to offer guests, needing to explain something like that.