Your nitro only helps if it's on you.

Nitroglycerin is more fragile than most people realize, and what degrades it usually isn't the dramatic stuff. A 2018 study in the American Journal of Cardiology tested sublingual tablets under ordinary carrying conditions. Tablets kept in a purse were still potent after two years. Tablets carried in a pants pocket had fallen below acceptable potency inside twelve months, which the researchers put down to body heat and the physical stress of being carried around all day.

Some of that comes down to the drug itself. Nitroglycerin is volatile, meaning it slowly leaves the tablet as vapor, and it adsorbs onto plastic and cotton. That's the reason the FDA label for Nitrostat is more specific about storage than most labels bother to be:

“NITROSTAT should be kept in the original glass container and tightly capped after each use to prevent loss of tablet potency.”

That instruction is why we size our two larger holders for the bottle rather than for loose tablets. The bottle goes in capped, sealed inside stainless steel, which puts a physical layer between it and your body heat and keeps sweat and rain out. You don't repackage anything, and the pharmacy label stays where it's useful, on the bottle, if a paramedic or an ER nurse ever needs to read it.