LOL. There's something nobody would have thought would be needed in a flight bag back when I started flying.
Note: Pepcid is listed on the FAA's "case by case basis" medication list. If you're reporting it as one of the OTC drugs you take, they may ask for more info.
There was a thread on heartburn a long time ago and Doc Bruce answered as to why... apparently it has a side-effect of sedation so FAA isn't thrilled about it.
https://www.pilotsofamerica.com/community/threads/acid-reflux-indigestion-heart-burn.50919/
Back when I was a stress-puppy and eating a lot of stuff I shouldn't have, I used it pretty heavily and it was the best outcome for me for my regular heartburn back then (other stuff just wasn't as effective for me)
There's a bottle of Pepcid Complete around here somewhere for the occasional "Whoa... mixing spicy ribs a bucket of mac and cheese and margaritas was a really bad idea, there, you idiot!" moments, but I recognize that FAA isn't super keen on the stuff and try to follow similar "get it out of your system" personal protocol for it, as some of the other OTCs they don't like, before flying.
I believe the phrase for the medical form is, "occasional use for heartburn, self-grounded" to be pedantic about it.
Not sure it'd be the right option for my flight bag, but I did used to have some little packets in there long long ago when I was constantly having heartburn back then. Nowadays I couldn't tell ya the last time I had bad heartburn. I think it was after I tried some weird fruity drink a friend suggested with a dinner out that had grapefruit juice in it. Citric acid in large quantities can really kick me in the butt. Always has. So I just avoid it.
Anyway. Just info for ya on that. Might peek at the FAA approved OTC list and switch to something they're happier about when flying. They're a little paranoid about any drugs that have a sedative effect -- there's a few NTSB reports with hints that the pilot had certain OTC drugs in their system that may have "contributed" to whatever causes pilots to become inattentive and run into things they shouldn't, like the ground...
As always, YMMV.