I carry bandaids, Ibuprofin, antibiotic cream, aspirin and Benedril. The first three are apt to be used for minor injuries, aspirin for a heart attack, and the last can be helpful if somebody is having an allergic reaction. I also carry a roll of gauze, tape, and a tourniquet.
I should carry some type of a splint but don't. Everything fits in a pouch so I can carry it in the woods with me. I do keep a bottle of hand sanitizer in my truck, which has 70% alcohol.
In a life threatening emergency you aren't going to be worrying about infection; your main objective is to stop the bleeding and your sweatshirt or tee shirt will work if necessary. Contrary to what some say, one thing you DON'T want to use is a tampon. They're designed to absorb blood, you want to stop it so that it will clot.
Which reminds me, I also have a couple tubes of clotting powder and a clotting sponge.