I don't think I've ever had a particularly bad bite or sting.
One time I got a mosquito bite on the back of my hand that puffed up, so I took some antihistamines and it went away. Another time I wasn't thinking things through and knelt in the grass (wearing shorts) to cut up a tree I'd cut down and only later noticed a collection of bites. They looked a bit angry at first but a dose of antihistamines and some stuff my wife uses on bites (I forget the name of it) and they went away pretty quickly.