I usual aim the bitters toward the back of my tongue. However a couple of times I overshot my target and the bitters hit my throat. That really burned! Gave me a coughing jag, producing a lot of mucus. It took a day for it to clear up. It was so uncomfortable, I ate a small amount of honey, hoping to sooth my throat. It helped a bit.
Now I'm much more careful and just go with the middle of my tongue.
I'm using Digestive Bitters from Herb Pharm until the bottle is finished then I'll get the Grape Bitters. Maybe they won't be as caustic.