Food dye sensitivity is not my friend. Blue #1 in it rendered it pretty much useless for my needs. Imagine the discussion with your doctor when you say, "Hey, I think I'm allergic to this antihistamine..." and get blown off. I also have a good number of allergies in my 30s I didn't have when I was young, so I totally agree with a poster above who mentioned that overflowing bucket.
One other thing I will note here is that Benadryl isn't good for glaucoma (or those with higher than normal eye pressures). I never had high eye pressures until I got all of my allergies and had to take medicine for them.
Always give the allergist a full-health run-down and mention these things
I have also been told that certain antihistamines can work on stomach acid (though I think that's more of an off label use).
