It is for burning pain mostly.

I discovered this by accident, several years ago. If you read the two
links from OBT above, I give the history.

I use AlkaSeltzer more in the summer, when I have burning in my feet at
night.

I've been researching it some, and connecting the dots as far as
food allergies go. Environmental allergy doctors use TriSalts to abort
challenges when elimination diets are done. If a positive occurs in the office
or at home, TriSalts are given for accidents/slips.

But I found that AlkaSeltzer really helps with burning in particular.
I just found that pain.org paper...on acid/pain. So I find that also connects...to the burst of bicarb you get with the AlkaSeltzer.
It is not really the aspirin per se, but the rest that seems to provide the relief.
The aspirin works on the pain of course, but is not essential to the burning.

AlkaSeltzer was really really useful when I was using metformin..which causes
a metabolic acidosis in some people. I would stop the diarrhea symptoms in
minutes for me!