Hydrate. Benadryl? Shower to wash off pollen. Eat hydrating and nourishing safe whole foods instead of food products. Rest.

Neti pot helps too.

Histamine sucks for sure! A shower does help if you are dealing with things like dust mites, pollen, mold etc. Just be sure you're not using extremely hot water it raises histamine and can make reactions worse. Another thing I can suggest is magnesium to stay calm because cortisol and histamine play off each other. This really stink if you have allergy induced asthma. I have used activated charcoal to reduce symptoms when I get what I call an attack. Mine are horrendous! I am allergic to so much that I researched and studied extensively. Activated charcoal helps the histamine receptors in the gut.

Know that if you use plain benadryl, with no other med in it, that you can take more than what the level says. I found this out when I developed vertigo and wasn't getting relief from the vomiting. A Dr, at my 5th visit (what a silly waste!) finally stated to me you can take all the meclizine you want! I went home and took 8 meclizine that day (label says 2 is max) and it cured the vertigo forever! So, basically, one can take benadryl, chlortrimeton 4 and 12mg and meclizine pretty much how much you need. Chlortrimeton 12 mg is best for me. Only place I know to get it is www.chlorphen12.com. It will be worth it I promise you!