When you need first-aid supplies most, you're usually not in the best frame of mind to search for them. A well-stocked first-aid kit keeps the items you need easy to find. Bandages, adhesive tape, gauze, and scissors are useful. To clean wounds, keep hydrogen peroxide or isopropyl alcohol (and cotton balls or swabs to apply it) on hand as well as antibiotic ointment (check expiration date). A first-aid kit is also a good place to store pain relievers.