Diarrhea, like most of your body’s natural processes, is a positive reaction. It is most often caused by a bacterial or parasite infection. In that case, the diarrhea is your body’s attempt to purge the bacteria/parasite from your body. Taking an anti-diarrhea medication like Imodium is like shoving a rubber stopper up your butt. It stops the diarrhea, doing nothing to address the actual cause of the problem. All you’re doing is allow that bacteria or that parasite more time to hang out inside your body and mess around. The only time such a medication is indicated is if you have to move or die, and the diarrhea is so frequent as to prevent your ability to move. As a Wilderness EMT, probably the only time that I’m going to administer Imodium to a patient is if the patient is shitting so frequently that it hinders the evacuation. Then I’ll plug the patient up and get him out to a hospital.

A far better solution for the common, mild cases of diarrhea is to simply let it run its course. Of course, you’ll be pooing out more water than usual so you’ll also want to increase your water intake to compensate. (You’ll see a lot of people claim that diarrhea is a leading cause of death among children, especially in less “developed” nations. It’s not actually the diarrhea that’s killing them, but the dehydration that results from it.) Whenever you increase water input, you also want to increase the amount of electrolytes that you’re consuming. That’s where the aforementioned Emergen-C comes in, or you can eat some salty nuts, salty jerky, or drink a salty bullion cube. Or you can explicity carry salt.

Of course, the best treatment for diarrhea is prevention. Like I said, the most common causes are bacteria and parasites. In the wilderness, your bacteria comes from poor sanitation and parasites from dirty water. So getting your water from the cleanest possible source and then treating it properly, as well as making a point of frequent washing of hands (particular after you poo and before and after touching any food items or cooking kit) is going to prevent most diarrhea.

If you do want to take something to treat diarrhea, then you want to make sure whatever it is is not just plugging you up, but actually addressing the infection. In my experience, I’ve found plain old grapefruit seed extract to work best. The GSE will attack bad bacteria, while leaving the good bacteria in your stomach alone (in the wilderness, I think it’s particularly important to make sure that you’re not taking something that’s going to wipe out everything in your stomach. You need that good bacteria). In addition to treating diarrhea, I use GSE to treat water and clean my toothbrush and water carriers (both at home and in the field). If the GSE doesn’t do anything for you, you could have a viral infection, which is a bigger problem.

You also have to consider the Good Samaritan thing and decide if you want to provide aid to others. My urban kit includes a mini-CPR mask. Obviously that’s not a self-aid item, but something I carry in case I have to perform CPR on somebody else. I also always carry gloves in both urban and wilderness kits, which are (almost) useless when I’m taking care of myself, but critical when caring for others.

I agree with what Avagdu said. For both urban and wilderness settings, the bulk of my kits are made up of dressings (sterile gauze, nonadhesive dressings, etc) and a bit of tape. The main difference between the two kits is the amount and size of the dressings. I’ve never carried drugs like ibuprofen or benadryl. The only vaguely drug-like thing I tend to carry is Emergen-C for electrolytes.

Sanitation is also crucial. Slapping a bandage on a small wound in an urban environment probably is not going to cause you a lot of trouble and, if it does, you’ll be sorry but you’ll have easy access to more definitive care. But if you bandage a wound — even a small one — without cleaning it in a wilderness environment, you stand a high chance of infection and could turn what was a small nick into a life-threatening injury. In the urban environment, a few alcohol prep pads will probably be all you need. In the wilderness, alcohol prep pads and a syringe are a decent minimum. Also consider a topical antibiotic, like Neosporin. A wilderness first aid kit should still be able to fit in your pocket.