It’s always a good idea to have a small first aid kit handy. Here’s the stuff that you should have in a small first aid kit that should be good to treat most cuts, scrapes, headaches, blisters, etc. that you’ll get when climbing.
Medical tape (you can wrap a small amount around a plastic pen or lolly pop stick; duct tape works, too)
Moleskin (for blisters)
Band-aids
Neosporin (disinfectant cream)
Ibuprofen (anti-inflammatory; reduces fever and pain)
Small knife (I have a Swiss Card and it’s freaking awesome. In addition to a knife, it has tweezers and scissors.)
Moist towelettes (for cleansing hands and wounds)
I keep all of this stuff in a small plastic Ziploc bag. The kit is always kept in the lid pocket of my top-loading day pack. I don’t climb with this first aid kit unless I climb with my pack (which I try not to do as much as possible), so I guess I take it mostly for cragging days. For multipitch stuff where I’m not carrying the pack, I sometimes pare down the kit to just a few items that I can stick in a pocket.
If you don’t want to buy all of those things individually, you can buy a small ready-made first aid kit. Click here to view first aid kids through Google Shopping, sorted by price from low to high. For a few bucks you can get a pretty sweet setup.
Any other suggestions? Do you keep a first aid kit with you when you climb? How about in your pack?
