The histamine reaction involves a acidic component. That is why the AlkaSeltzer Gold works well.

Also the pain receptors use an acidic component and that is why some people notice an improvement in pain. If you read the reviews on Amazon, you'll see the Lyme community uses the Gold for Lyme pain (neuropathy).

I've used AlkaSeltzer original for many many years. When my left knee (my good knee) had that terrible sudden swollen, red painful attack just before Xmas, I was using the Original too much I thought, but it was working really well. I think I was having a gout attack since I have elevated uric acid shown by my blood tests. Searching for a non RX solution I ran across the bicarbonate suggestion, so hence the Gold.

I read about the connection between pain and acidic receptors years ago... so here is one link you can read and you can pursue this further if you want online:
People of the Acid: Acidosis and Pain - Pain Online
The bicarb intervention is temporary...but it does work. That is why I have posted about AlkaSeltzer original here so often.

Histamine....
Freshness Counts: Histamine Intolerance - Diagnosisiet
Looking at the list of high histamine foods, and seeing that massive sauerkraut explains my severe intolerance to this fermented cabbage! I still joke that sauerkraut could KILL me someday, so I avoid it strenuously! LOL

This is why I have a thread on our subforum about histamine reactions and food. My adult son and I both had a reaction on vacation at a family restaurant about 5 yrs ago, which we decided was from "old" frozen perch that was its specialty and delicious but sadly was providing the histamine to make us burn like crazy an hour later! I assumed my burning was my PN then, but my son does not have PN and he was pulling of his shoes and socks frantically. So I had AlkaSeltzer fortunately with us, and that did the trick.

Taking the bicarb (AlkaSeltzer) I believe "blows the acid off" receptors quickly as it is effervescent and absorbed really quickly. We studied AlkaSeltzer in college...it is unique in its speedy absorption. But alas, it is only a temporary solution, but it does work. It works enough to let you get to sleep, or do things during the day, until it wears off.