I was not aware of the histamine trigger component of ET. I'd assumed that my shortness of breath when backpacking was due to not getting older. I will be more consistent with antihistamine use and see if that makes a difference. Can anyone suggest an antihistamine that doesn't dry cause dryness of mouth and corneas? I don't take any with decongestants but all, including the Zyrtec I'm using now, have that effect.