I've been through it many times, it takes about 25 to 30 mins to start shutting down my respiratory system. I'm 10 to 15 mins away from a hospital.
Plus I'm alot more careful and aware of my surrounds now days. I haven't been stung, going on 10 years now...the last time, I got hit 5 times 3 on the back of my head and 2 times on my cheek and chin. I was at our ranch, 150 miles from San Antoino.
I took 2 benadryl and by the time I got to IH35,(about 50 miles from the ranch) and headed towards SA everything was ok...no problems, no swelling. Lucky? Idk but still, I take no chances.