Yeah, for those with a mast cell disorder either in addition to "conventional" allergies (Raises hand). Or instead of them, the cornerstone of the treatment involves h1 and H2 antihistamines. Typically Zyrtec and Zantac.
The difference is, with normal allergies, you have the IgE antibodies that stick to the protein, then trigger mast cells to release histamine from the mast cell's IgE receptors. So what's going wrong is the cells that make the IgE antibodies in the first place. With a mast cell disorder your mast cells can be triggered by all different kinds of things, including smells, stress (physical or emotional) heat, cold, sunlight, foods etc. With a mast cell disorder, you can have reactions ranging from just "brain fog" all the way up to anaphylaxis from triggers that can be far more difficult to avoid. Or even impossible to avoid. I.e. Idiopathic Anaphylaxis. You need to blockade the histamine receptors as much as possible, because histamine itself will trigger the mast cells to release more histamine. And the mast cells have H1, H2, H3, and H4 receptors. Sadly, we only have drugs to blockade H1 and H2 on the market.