Ask 10 thru-hikers what's in their first aid kit and you'll get 10 different answers, but the injuries they actually treated last season are boringly consistent: blisters, small cuts and scrapes, sore joints, an upset stomach, the occasional sting. Almost nobody splints a femur. Almost everybody tapes a heel.
That's the logic behind an ultralight first aid kit. You're not carrying less because you don't care about safety. You're carrying less because you've matched the kit to the injuries that actually happen, and because the biggest category, foot care, runs on a few grams of tape and wipes. (We've covered that side in depth in our guide to preventing and treating blisters on long-distance hikes.)
This post covers what belongs in the kit, what to leave home, how our own First Aid & Repair Kit compares honestly to the most popular alternative, and when building your own makes more sense.
The weight target, and what drives it
A realistic ultralight first aid kit lands under 100 g. Past that point you're usually carrying one of 3 things: quantities sized for a group instead of 1-2 hikers, trauma supplies you're not trained to use, or full-sized packaging (a whole bottle of ibuprofen, a full roll of tape) when the trail-sized portion weighs a tenth as much.
The weight you keep should buy coverage across 4 jobs:
- Feet: Leukotape, and something to dress a drained blister, like our Skin Shield pre-cut blister patches. This is the gear you'll use weekly, not hopefully-never.
- Wounds: a few bandages, a gauze pad, alcohol wipes, antibiotic ointment. Enough to clean and close small cuts and keep them clean for days.
- Meds: single-dose packets of an anti-inflammatory, an antihistamine, and an anti-diarrheal. These treat the 3 ailments most likely to actually stop you: pain and swelling, allergic reactions, and gut trouble.
- Backstops: a needle (blisters, splinters, sewing), and water purification tablets in case your filter fails. Cheap grams that cover ugly scenarios.
What can stay home for most 3-season hikers: SAM splints, tourniquets, suture kits, snake bite kits (suction kits are useless anyway), scissors bigger than tiny, and a second of anything you can restock in town. Improvise splints from trekking poles and sleeping pads; that's standard wilderness practice and it weighs nothing.
The case for combining first aid and repair
Here's the thing the traditional first aid kit misses: on a thru-hike, a dead sleeping pad is a safety problem. So is a torn rain jacket in the Sierra or a ripped pack strap 40 miles from town. Hikers respond by carrying 2 kits, a medical one and a repair one, with 2 pouches and plenty of overlap (tape, needle, tiny scissors).
We built the First Aid & Repair Kit to be both in 1 pouch at 70 g. Inside a weatherproof DCF pouch (130 × 90 × 20 mm, YKK Aquaguard zipper):
- First aid: 6 waterproof bandages, 8 alcohol wipes, 1 gauze pad, 1 yd of Leukotape, 4 antibiotic ointment packets, 3 sting relief wipes, 3 pouches of Advil, 2 pouches of Benadryl, 2 anti-diarrheal packets.
- Repair: 4 Threadlock Patches for fabric tears, 4 Airlock Patches for inflatables, a full UL Repair Spool (1 yd Gorilla Tape, 3 yd bonded nylon cord, needle), and super glue.
- Backstop: 10 water purification tablets.
The Leukotape comes rewound on a mini spool, so you're carrying a yard of the good blister tape, not a token strip. The honest trade-off: it costs more than assembling the pieces yourself, and if you already own a repair kit you love, you're paying for some duplication. What you're buying is 1 pouch, no gaps, and contents that were chosen as a system.
How it compares: Adventure Medical Kits Ultralight/Watertight .5
The AMK Ultralight/Watertight .5 is the default recommendation in this category, and it's a good kit. The manufacturer lists it at 3.6 oz (about 102 g), rated for 2 people over 1-2 days, with a waterproof DryFlex inner bag inside a water-resistant outer bag.
| Igneous First Aid & Repair Kit | AMK Ultralight/Watertight .5 | |
|---|---|---|
| Listed weight | 70 g | 3.6 oz (about 102 g) |
| Scope | First aid + gear repair + purification tablets | First aid only |
| Blister care | 1 yd Leukotape on a spool | Moleskin-style blister kit |
| Gear repair | Fabric and inflatable patches, tape, cord, needle, glue | None |
| Pouch | DCF, YKK Aquaguard zipper | DryFlex inner bag + DWR outer bag |
The fair summary: if you want a pure medical kit at the lowest price, the AMK .5 is the value pick and a proven one. If you'd otherwise carry the AMK plus a separate repair kit, the combined kit is lighter than the pair and covers more failure modes. Run the comparison against what you'd actually carry in total, not kit versus kit.
The DIY route
Plenty of experienced hikers build their own kit in a zip bag, and done well it can be the lightest option of all. The realistic pros and cons:
- For: total control of contents and weight, you already know where everything is, and you can tailor meds to your own body (prescriptions, higher-dose anti-inflammatories, personal allergies).
- Against: buying single-serving components means buying full-size everything first, the first assembly takes a genuine evening, and the most common DIY failure is quiet omission: the kit slowly loses pieces over a season and nobody audits it.
If you go DIY, steal the category list above as your checklist, and weigh the finished bag. DIY kits that never get weighed have a way of growing.
About that DCF pouch (and a correction)
An earlier version of this post claimed that DCF is "15 times stronger than steel." That's not right as written, and it's worth being precise. The 15x figure is the fiber maker's claim for Dyneema fiber itself, and it refers to strength-to-weight, not absolute strength: per gram, the ultra-high-molecular-weight polyethylene fiber is up to 15 times stronger than steel. Dyneema Composite Fabric is a laminate that sandwiches a grid of those fibers between polyester films, and the laminate's numbers are its own.
What DCF actually gives a first aid pouch is simpler to defend: it's very light for its tear strength, it's waterproof rather than water-resistant, and it doesn't absorb water, so the pouch weighs the same soaked as dry. Paired with a water-repellent YKK Aquaguard zipper, the contents stay dry through the kind of all-day rain that eventually gets into most fabric pouches. That's the job. No steel comparison required.
Whichever kit you choose, keep it stocked
A first aid kit on a thru-hike is a consumable. Tape gets used, wipes get used, ibuprofen definitely gets used, and the kit you finish a 5-month hike with is not the kit you started with unless you restock it. We've written a full guide to restocking first aid and repair supplies on the trail: what runs out first, what trail towns actually stock, and when a mail drop is worth the hassle.
The best kit is the one that's light enough that you never resent carrying it, complete enough that you never regret it, and full when you need it. Everything else is preference.
