A first aid kit is the one piece of gear you hope never to use, which makes it tempting to either over-pack it or leave it behind entirely. Both mistakes are common. The ultralight approach is different: carry a small kit built around the injuries that actually happen on the trail — blisters, small cuts, sprains, stomach problems, and allergic reactions — and leave the hospital-grade equipment at home. A good kit weighs 3 to 5 ounces, fits in a small zip bag, and gives you the tools to handle the vast majority of backcountry medical problems.

Start with wound care: a few adhesive bandages in different sizes, a small roll of medical tape, a couple of sterile gauze pads, and antiseptic wipes. Add blister care — Leukotape or moleskin and a needle for draining large blisters — because foot problems are the most likely issue you will face. Include a small pair of tweezers for splinters and ticks, and a few safety pins, which can fix gear as well as bandages. Wrap it all in a zip bag that doubles as a waterproof container. This core kit weighs about 2 ounces and handles 90 percent of trail injuries.

A small selection of medications adds real capability for very little weight. Ibuprofen covers pain and inflammation from sprains and overuse, while antihistamines handle allergic reactions to stings, plants, and food. Anti-diarrhoea tablets are essential on any trip where water quality is uncertain, and oral rehydration salts can be a trip-saver if you do get sick. If you have any personal prescriptions, including an EpiPen, they belong in your kit — and your hiking partners should know where they are. Keep medications in their original packaging or a labelled bag, and check expiry dates before every trip.

Most pre-made first aid kits are too heavy because they include items you will never use on the trail. Leave behind the large trauma dressings, the splints, and the bulky scissors — a bandana and a trekking pole make a better improvised splint than anything you can buy. Skip the instant cold packs, which are heavy and single-use; a cold stream works better. Avoid carrying a full bottle of every medication — repackage into a few doses in a tiny zip bag. The goal is not to run a field hospital; it is to stabilise a problem and get yourself to help if needed. Every item in your kit should answer the question: will I realistically use this on this trip?

A first aid kit is only as good as the person carrying it. Take a wilderness first aid course if you hike regularly — a one-day or two-day course teaches you how to assess injuries, improvise splints, recognise dehydration and hypothermia, and decide when to evacuate. Learn how to treat the specific risks of your area, whether that is tick bites, heat illness, or altitude sickness. Practise using your kit at home so you can find things quickly in the dark or in the rain. And always tell someone your route and expected return time before you leave, because the most important piece of safety equipment is a person who knows where you are.

Keep your first aid kit in the same place on every trip — ideally an outside pocket or the top of your pack — so you can reach it fast when someone is hurt. Check it before each trip: replace used items, check expiry dates, and adjust the contents for the season and the group size. On a solo trip you can go lighter; with a group, carry a slightly larger kit and make sure everyone knows where it is. A well-maintained ultralight kit weighs almost nothing, costs very little, and gives you the confidence to handle whatever the trail throws at you. That peace of mind is worth far more than the three ounces it costs.