DIY home surgeons will be excited to know epinephrine can actually be used with lidocaine (a numbing agent) to restrict blood vessels for faster wound repair. (Note: Cracked in no way condones performing self-surgery.) When sanitization resources become limited, the speed with which a wound can heal will have a drastic impact on survival rates. The longer a wound stays open and bloody, the more likely you are to get infections. Infections have historically been some of the most deadly and difficult-to-treat medical conditions, and even today they are not always easily survivable.
You probably get it by now, but we're going to keep rubbing your face in the facts, nonbeliever. A bit of body odor might seem like a minor inconvenience, but it gets a whole lot more important when sneaking up on an animal that hasn't spent the last millennia losing its survival instincts means the difference between feasting and starving. Finally, an accidental fire near your ammo stores that could easily have been extinguished with a dose of nonflammable powder will certainly put a damper on your plan to make it through the end times in one piece.
Earthquakes, tornadoes, and hurricanes can cause you to leave your home or even be trapped there. Roads could be blocked due to fallen trees, power lines, or even damaged earth from the natural disaster. Rescue crews can not be in all places at once. You may have to wait it out for quite a while before its over. You won't be able to go to the store or to the corner market.