Mindy,
I discovered the article entitled Histamine and Histamine Intolerance (Maintz, Am. J. of Clinical Nutrition) almost 6 weeks ago. It explained so much. I am not perfect following a low histamine diet, but I can sure tell the difference when I have something I shouldn't. My symptoms are nasal blockage, decreased lung capacity, and lowered voice, but the symptoms are variable person to person. I was on COPD meds for almost a year and still use my albuterol to loosen my lungs if I need to, but usually less than once a month now that my diet meets my needs. Afrin will help the nose in an acute situation too.
I used Allegra and it helped, but with my 23andme results I learned it was a cardiac risk for me, so I switched to loratdine (generic claritin). I don't know whether that helps or not. I haven't used the zantac because I have had poor protein absorption, low stomach acid, muscle wasting, etc. and I didn't think it would be a good idea, but I'm willing to learn.
I gave the articles to my allergist, but he does not see the value of a diagnosis.
Benedryl is the only antihistamine that has been found to increase the activity of the DAO enzyme, which is the one that works in the digestive tract.
I don't have masto and I just limit histamine, not tyrosine, which is a bit more liberal than the one in camas' signature. My main things are: avoid tomatoes, peppers, and spinach, aged dairy, aged or fermented anything, pre-cooked meats, and the spices listed there.
I also have adrenal and thyroid problems, not sure what we're going to do about those, I'm on thyroid, but my NP would like to get my adrenals working again, so thinks that any supplements will be a negative feedback to decrease any output that they might attempt. I was low from pregnenelone to cortisol, dhea to estrogen. I supplement OTC progesterone so that I don't run out of cortisol again, but don't have a solution. It helps both inflammation and blood sugar stability.
It's a long road back, but I'm hoping that when the other things start working, maybe I'll have the gut juices and gut bugs to digest and absorb what I eat and I can go back to the person I was two years ago.
Good luck to you!